The invention relates to poly(arylcy- clobutene) monomers.

The poly(arylcyclobutene) monomers of this invention are useful in the preparation of a wide range of polymeric compositions. These polymeric compositions are useful in films, as molded articles, in coatings, as adhesives, and in composites.

In recent years the search for high-perfor¬ mance materials, especially high-temperature-resistance polymers, has gained momentum. In order for a material to be useful at high temperatures, it must fulfill sev¬ eral requirements including a high melting or softening temperature, a high modulus or rigidity at elevated tem¬ perature, a resistance to solvent and chemical degrada- tion, and toughness. The intrinsic thermal and oxida- tive stability of aromatic structures has long been rec¬ ognized, and a variety of polymers have been made in

which benzene rings are linked together by various con¬ necting groups. Among the more stable aromatic polymers that fulfill the requirements of high-temperature resis¬ tance are the polybenzimidazoles, the polybenzoxazoles, polyimides, and some polyamides, such as the polyaramides. Of these polymers, the polyimides have had the most inter¬ est.

The major difficulty encountered in the comr mercial development of these materials is that they are usually obtained in the form of a powder which cannot be readily fabricated into useful objects.

The polyimides prepared from aliphatic dia- mines and aromatic dianhydrides are generally soluble and thermoplastic. Aliphatic polyimides have been pre- pared from bis(dienophiles) and a diene such as a bis- -diene. In many cases, such reactions proceed with the evolution of gases and other volatile components.

Aromatic polyimides, such as polypyromellit- , imides, have a spectrum of superior properties. These polyimides may be prepared by the reaction of an aromatic dianhydride with an aromatic diamine to give a soluble polyamic acid, which on cyclodehydration gives the insol¬ uble desired product.

High performance plastics reduce the weight of mechanical components, and not just by virtue of their densities. Their high performance properties allow greater design stresses, and often elements can be downsized accordingly. In recent years, aromatic

polyimides have become widely accepted as premium, high performance engineering plastics. These resins are well-known for having excellent properties at elevated temperatures (i.e., chemical resistance and mechanical strength) but are also costly. Historically, polyimide resins are difficult to fabricate into objects other than fibers and films. The most common methods of manufacturing parts having high strength and temperature properties are hot compression-molding, machining from hot-compression, and molded or extruded rod) . Given the synthetic and fabrication difficulties, a new route to polyimides and other high performance plastics is desir¬ able.

Many monomers used heretofore to prepare thermally polymerizable compounds have a poor shelf- -life and are unstable in the presence of oxygen or oxygen-containing gases. Further, many processes for the polymerization of thermally polymerizable compounds result in the generation of volatile components, which can create problems in the product such as the creation of voids in molded articles. Further, the removal of such volatile by-products can create problems. Also, many of such polymerization processes require the use of curing agents, initiators or catalysts. The use of such curing agents, initiators or catalysts often results in polymers which contain impurities which may effect the final properties.

Monomers which are polymerized through thermal mechanisms which do not require the use of catalysts, initiators or curing agents, and which do

not form volatile by-products are needed. Monomers which polymerize by thermal mechanisms, which have a good stability, shelf-life, and are stable in the pres¬ ence of oxygen are desirable. Monomers which form poly- mers by thermal polymerization mechanisms, with a good modulus, which are thermally stable, which have low water pickup, are reasonably hard and are insoluble are needed.

The invention is a poly(arylcyclobutene) characterized by comprising aryl moieties with one or more cyclobutene rings fused to each aryl moiety, wherein the aryl moieties are directly bonded to one another or are connected by a bridging member wherein the bridging member is (1) a polyvalent inorganic radical or (2) a polyvalent organic radical which (a) contains one or more heteroatoms comprising oxygen, sulfur, nitrogen or phosphorus, or (b) one or more aromatic radicals.

The novel compounds of this invention are useful in the preparation of polymeric compositions. Such polymeric compositions can be prepared by heating the monomers to a temperature at which such monomers polymerize. These monomers upon heating to the appro¬ priate temperature undergo a polymerization in which no volatiles are generated, wherein there is no need for a catalyst, curing agent or initiator. These mono¬ mers have a surprisingly good shelf-life and stability to oxygen-containing gases. The polymers prepared have a good modulus, are thermally stable, have a low water pickup, are reasonably hard and insoluble.

This invention relates to poly(aryleyelobu- tenes), ^' wherein poly(arylcyclobutenes) refers herein to a compound containing 2 or more arylcyclobutene moieties connected either by a direct bond or bridging member. An arylcyclobutene moiety refers herein to an aryl group which contains one or more cyclobutene rings fused to the aromatic rings. Aryl refers herein to any aromatic moiety. Preferred aromatic moieties include benzene, naphthalene, phenanthrene, anthracene, a biaryl moiety, or 2 or more aromatic radicals bridged by alkylene or cycloalkylene moieties. More preferred aromatic radi¬ cals are benzene, naphthalene, biphenyl, binaphthyl, diphenyl alkane or diphenyl cycloalkane radicals. The most preferred aromatic radical is a benzene radical.

The aryl radical and cyclobutene ring may be substituted with a variety of substituents. Such substi- tuents may be electron-donating or electron-withdrawing groups. Examples of such substituents include cyano, halo, carboxy, hydrocarbyloxy, carbonyl, alkanoyl, aroyl, alkylsulfonyl, alkylsulfonoyl, amino, amido, or aryl groups.

The arylcyclobutene moieties are connected herein by a direct bond or bridging member. Bridging members comprise (1) a polyvalent inorganic moiety, or (2) a polyvalent organic moiety containing (a) one or more heteroatoms, comprising 0, P, N, or S, or (b) one or more aromatic radicals. The bridging member or direct bond connects the arylcyclobutene moieties through the aryl radical.

Polyvalent inorganic moiety refers to any inorganic moiety which is capable of bonding to 2 or more aryl radicals. Such polyvalent inorganic moieties can be covalently or ionically bonded to the aromatic radical. Examples of polyvalent inorganic moieties include oxygen, phosphorus, phosphorus oxide, sulfur, nitrogen, polysiloxanes, polyvalent metals, sulfoxide, sulfone, a polyvalent metal bound to a polyvalent oxy¬ genated moiety wherein the polyvalent oxygenated moiety can be further bound to an aryl radical (for example, a polyvalent carboxylate salt). Preferred polyvalent inor¬ ganic moieties include oxygen, sulfur, polysiloxanes, and polyvalent metals bound to polyvalent oxygenated moieties.

The polyvalent organic bridging member can be any polyvalent organic moiety containing one or more heteroatoms, comprising oxygen, nitrogen, phosphorus, or sulfur, or an organic moiety containing one or more aromatic radicals, which can link 2 or more aryl radi- cals. Preferably, the polyvalent organic bridging mem¬ ber is a hydrocarbon poly-yl which is bonded to function- alized linking groups or a hydrocarbon poly-yl which con¬ tains an aromatic radical. Hydrocarbon poly-yl is a hydrocarbon moiety which is bonded to 2 or more linking groups, wherein the hydrocarbon poly-yl may further con¬ tain one or more of the hereinbefore defined heteroatoms. Included within the term hydrocarbon are any organic radicals containing carbon and hydrogen atoms. Hydro¬ carbons include the following organic radicals: alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, aromatic radicals, wherein aromatic is as defined hereinbefore,

alkyl-substituted aromatic radicals, and aryl-substi- tuted aliphatic radicals.

Linking group refers herein to any group which is capable of linking a hydrocarbon radical to an aryl radical. Linking groups include, for example, oxygen, sulfur, sulfoxide, sulfone, nitrogen, phos¬ phorus, phosphorus oxide, oxycarbonyl, amido, car- bonyl, carbonyldioxy, cyclic amido, carboxamidooxy, ureylene, carbonyloxycarbonyl, ammonium carboxylate salt and imido. Preferred linking groups are oxygen, sulfur, nitrogen, carbonyloxy, amido, carbonyldioxy, or cyclic amido. More preferred linking groups are carbonyloxy and amido.

Preferably the arylcyclobutene moieties are connected by direct bond or polyvalent organic moieties containing (1) one or more heteroatoms or (2) one or more aromatic radicals. Most preferably, the arylcyclo¬ butene moieties are connected by the bridging members comprising the polyvalent organic moieties containing (1) one or more heteroatoms or (2) one or more aromatic radicals.

In one preferred embodiment, the polyvalent bridging member is a divalent bridging member. More pre¬ ferred divalent bridging members include dicarbonyloxy hydrocarbylene, dicarboxamido hydrocarbylene, dicarbon- yldioxy hydrocarbylene, dioxyhydrocarbylene, dithiohy- drocarbylene or an aromatic radical-containing hydro¬ carbylene group.

Even more preferred divalent organic bridg¬ ing members are dicarbonyloxyhydrocarbylene, dicarbox- amidohydrocarbylene, di(carbonyloxy)hydrocarbylene, dioxyhydrocarbylene, and dithiohydrocarbylene.

Examples of polyvalent organic bridging members include the following: polyoxy(alk-poly-yl), polyoxy(ar-poly-yl), polyoxy(alkar-poly-yl), polyoxy(ar- alk-poly-yl), polythio(alk-poly-yl), polythio(ar-poly- -yl) _/ polythio(alkar-poly-yl), polythio(aralk-poly-yl), polyamido(alk-poly-yl), polyamido(ar-poly-yl), polyamido- (alkar-poly-yl), polyamido(aralk-poly-yl), polycarbonyl- oxy(alk-poly-yl), polycarbonyloxy(ar-poly-yl), polycar- bonyloxy(alkar-poly-yl), polycarbonyloxy(aralk-poly-yl), polycarbonyldioxy(alk-poly-yl), polycarbonyldioxy(ar- -poly-yl), polycarbonyldioxy(alkar-poly-yl), polycarbon¬ yldioxy(aralk-poly-yl), polyamino(alk-poly-yl), poly- amino(ar-poly-yl), polyamino(alkar-poly-yl), polyamino- (aralk-poly-yl), polycyclicimido(ar-poly-yl), polycyclic- imido(alkar-poly-yl), polycyclicimido(aralk-poly-yl), polycarbonyl(alk-poly-yl), polycarbonyl(ar-poly-yl), polycarbonyl(alkar-poly-yl), polycarbonyl(aralk-poly- -γl)/ polyimido(alk-poly-yl), polyimido(ar-poly-yl), polyimido(alkar-poly-yl), polyimido(aralk-poly-yl), polyureylene(alk-poly-yl), polyureylene(ar-poly-yl), polyureylene(alkar-poly-yl), polyureylene(aralk-poly- -yl), polycarboxamideoxy(alk-poly-yl), polycarboxamide- oxy(ar-poly-yl), polycarboxamideoxy(alkar-poly-yl), poly¬ carboxamideoxy(aralk-poly-yl), ar-poly-yl, alkaryl-poly- -yl, aralkyl-poly-yl, and alkenoic-poly-yl.

Hydrocarbyl means herein an organic radical containing carbon and hydrogen atoms. The term hydro¬ carbyl includes the following organic _^ radicals: alkyl,

alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, ali¬ phatic and cycloaliphatic aralkyl and alkaryl. Ali¬ phatic refers herein to straight- and branched-, and saturated and unsaturated, hydrocarbon chains, that is, alkyl, alkenyl or alkynyl. Cycloaliphatic refers herein to saturated and unsaturated cyclic hydrocarbons, that is, cycloalkenyl and cycloalkyl. The term aryl refers herein to biaryl, biphenylyl, phenyl, naphthyl, phenan- threnyl, anthracenyl and two aryl groups bridged by an alkylene group. Alkaryl refers herein to an alkyl-, alkenyl- or alkynyl-substituted aryl substituent wherein aryl is as defined hereinbefore. Aralkyl means herein an alkyl, alkenyl or alkynyl group substituted with an aryl group, wherein aryl is as defined hereinbefore. ^c ι_,20 ^allς yl includes straight- and branched-chain methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl groups. C.^ alkyl includes methyl, ethyl, propyl, butyl and pentyl.

Cycloalkyl refers to alkyl groups containing one, two, three or more cyclic rings. Cycloalkenyl refers to mono-, di- and polycyclic groups containing one or more double bonds. Cycloalkenyl also refers to cycloalkenyl groups wherein two or more double bonds are present.

Hydrocarbylene refers herein to a divalent hydrocarbon radical. Poly-yl refers herein to a poly¬ valent radical, for example, ar-poly-yl refers to a polyvalent aromatic radical. Poly refers herein to two or more.

-10- Preferred poly(arylcyclobutenes) correspond to the formula

wherein B is a direct bond or bridging member which comprises (1) a polyvalent inorganic radical, or (2) a polyvalent organic radical containing (a) one or more heteroatoms comprising oxygen, sulfur, nitrogen, or phosphorus, or (b) one or more aromatic radicals; Ar is an aromatic radical which may be substituted; R is separately in each occurrence hydrogen or an electron- -withdrawing or electron-donating substituent; m is an integer of 1 or more; and n is an integer of 2 or more, with the proviso that B can only be a direct bond wherein n is 2.

In one preferred embodiment, the aromatic radical is benzene and m is 1. In this preferred embod¬ iment, the poly(arylcyclobutenes) can be referred to as poly(benzocyclobutenes). Preferred poly(benzocyclobu- tenes) correspond to the formula

wherein a is separately in each occurrence the integer 0, 1, 2, or 3; and B, R, and n are, as defined hereinbe¬ fore. In formula II, a is preferably 0 or 1, and most

preferably 0. R is preferably hydrogen, a cyano, or hydrocarbyloxycarbonyl group; more preferably hydrogen or cyano; and most preferably hydrogen.

In one embodiment, B can be a polyvalent inorganic bridging member, wherein inorganic bridging member is as defined hereinbefore. Preferable inorganic polyvalent moieties include -0-, -S-, -P-, -N-, ^•

O 0 0 0

II II tl II

-P- ,. -S- , -S- , M- O-C->_ n, , n valent M

II

0

or

wherein M is a metal; R is an alkyl, aryl, alkaryl, aralkyl, alkoxy, aryloxy, alkaryloxy or aralkyloxy; and b is an integer of 1 or greater. More preferable poly¬ valent inorganic bridging members include -0-, -S-, -N-,

O

II fO-C* _n

or

Polyvalent organic radical is as defined here¬ inbefore. Preferred polyvalent organic radicals include- ^• those wherein B is (a) the formula X-(Z wherein X isi a hydrocarbon poly-yl radical wherein the hydrocarbon poly-yl can contain a heteroatom of oxygen, phosphorus, sulfur or nitrogen, and Z is a functionali2ed linking moiety; or (b) a hydrocarbon poly-yl containing one or more aromatic moieties. Hydrocarbon poly-yl is as defined hereinbefore. The functionalized linking moiety is as defined hereinbe- fore. Preferably, X is an alk-poly-yl, cycloalk-poly-yl, ar-poly-yl, alkar-poly-yl, a biaromatic alkylene or cyclo¬

erein r is a C., _2Q straight- or branched-chain radical or a cycloalkylene radical and p is an integer of between about 2 and 20, inclusive. Most preferably X is CH _. p, phenylene ,

Preferably, Z is 0, S , N, P,

0 . 0 0 0 0 0 0

II II II II II tl 11 oc- , -oco- , -c- , -COC- , -CNH- , -OCNH-

-13-

0

0 0 O II tl II -NHCNH- ■CNHC- -CO ^w H ₃ ^w N - or -N

II

0

more preferably O, S ,

0

0 0 0 II

II II II

-OC- , -OCO- , -CNH- or -N ^C

II

0

and most preferably

0 O

II

-OC- or ■C H-

Preferred poly(benzocyclobutene) monomers include those with carboxamide-linking groups wherein the bridging members correspond to the formulas

O O tl II

-CN-X-NC-

I I

H H

and

O O

II II

-NC-X-CN-

I f

H H

those with carbonyloxy-linking groups wherein the bridging members correspond to the formulas

O O

II II

-CO-X-OC-

and

0 O

II II

-OC-X-CO-

those with carbonyldioxy-linking groups wherein the bridging member corresponds to the formula

0 0 -OCO-X-OCO-

those with oxygen-linking groups wherein the bridging member corresponds to the formula

-0-X-O-

those with sulfur-linking groups wherein the bridging member corresponds to the formula

-S-X-S-

and those with cyclic imid-linking groups wherein the bridging member corresponds to the formula

wherein X is as hereinbefore defined. More preferred bridging members which contain carboxamide-linking groups correspond to the following formulas:

0 O -CNH CH Υ- rNHC-

0 O -NHCfCH^C H-

and

wherein p is as defined hereinbefore and p is an inte¬ ger of 1 or greater, preferably between 1 and 20. More preferred bridging members with carbonyloxy-linking groups correspond to the formulas:

-co{c& 2,-h'p c-

O 0

0 o

■0CfCH- rC0- z p

and

wherein p is as defined hereinbefore. More preferred bridging members wherein the linking group is carbonyl- dioxy include those which correspond to the following formulas

0

II

-OCO{CH ₂ - -OCO-

and

wherein p is as defined hereinbefore. More preferred bridging members with oxygen-linking groups include those which correspond to the formulas

-O CH^-

and

wherein p is as defined hereinbefore. More preferred bridging members with sulfur-linking groups, include those which correspond to the formula a

-SfCH-^S-

wherein p is as defined hereinbefore. More preferred bridging members with cyclic imid-linking groups include those which correspond to the formula

In one preferred embodiment, the polyvalent organic bridging member contains one or more aromatic radicals, and such bridging member generally corresponds to the formula

3 " ^" wherein Ar is as hereinbefore defined; R is separately in each occurrence an alkylene, cycloalkylene or alkenyl- ene radical; r is independently in each occurrence 0 or 1; and q is 1 or greater. R 3 is preferably a C, _2Q alkylene or C ₁ _ _2Q alkenylene. R is more preferably ^C _l - ₁ 0 ^a ^ylene or C, , _Q alkenylene. R is even more preferably C, ₄ alkylene or C, ₄ alkenylene, with -CH=CH- being most preferred. Preferably q is between 1 and 20, most preferably between 1 and 10. In a more preferred embodiment, the aromatic radical hydrocarbon to the formula hereinbefore

The poly(arylcyclobutene) monomers of this invention can be prepared by several synthesis schemes. The preferred methods of preparation of such monomers are described hereinafter.

In one synthesis scheme, an alkyl-substituted aromatic compound ^' which is further substituted with an aryl deactivating substituent is chloroalkylated in a position ortho to the alkyl group. In the preferred embodiment wherein the aromatic compound is benzene, the starting material corresponds to the following for¬ mula

wherein R is as defined hereinbefore; R 1 i.s any aryl deactivating substituent; and c is an integer of 0, 1,

2, or 3. The alkyl-substituted aromatic compound is chloroalkylated by contacting the alkyl aromatic com¬ pound with a chloroalkylating agent and thionyl chlo¬ ride in the presence of an iron chloride catalyst so as to result in a product which contains a chloroalkyl group ortho to the alkyl substituent. In the embodi- ment wherein the aromatic compound is a benzene ring, the product corresponds to the formula

wherein R is as defined hereinbefore and R is an aryl deactivating group. R is preferably a hydrocarbyloxy- carbonyl, carboxamide, hydrocarbylcarbonyl, carboxylate, halocarbonyl, nitrile, nitro, sulfone or sulfoxide group. R is more preferably a halo or hydrocarbyloxycarbonyl

group, with hydrocarbyloxycarbonyl being the most pre¬ ferred group. Preferably c is 0 or 1, most preferably 0.

In this process the chloroalkylating agent is preferably chloromethyl methyl ether, although other chloroalkylating agents such as bis(chloromethyl) ether could be used. At least a 2:1 molar excess of the chloroalkylating agent to the alkyl-substituted aro¬ matic compound is needed. It is preferable to use at least a 3:1 ratio of chloroalkylating agent to alkyl aromatic compound. The catalyst is ferric chloride (FeClg) while the cocatalyst is thionyl chloride. The catalyst can be present in between 0.05 and 1.0 mole per mole of alkyl aromatic. More preferably between 0.1 and 0.4 mole of catalyst are present for each mole of alkyl aromatic compound. Preferably between 0.05 and 1.0 mole of thionyl chloride per mole of alkyl aromatic is used, more preferably between 0.1 and 0.4 mole per mole of alkyl aromatic.

This process can be performed at a tempera¬ ture of between 40°C and 80°C, preferably 40°C and 60°C. Below about 40°C, the reaction rate is low. The boiling point of some of the components of the reaction mixture starts at about 60°C.

This process can be performed by contacting the alkyl aromatic compound with the chloroalkylating agent, catalyst and cocatalyst in a suitable solvent. Suitable solvents include chlorinated hydrocarbon sol¬ vents. Thereafter the reaction mixture is heated to the appropriate temperature. The product can be recov¬ ered by quenching the reaction mixture with alcohols or

water to inactivate the chloroalkylating agents remain¬ ing, stripping off the volatiles and washing out the catalyst with water. The product thereafter is recov¬ ered by distillation.

The ortho chloroalkylated alkyl aromatic compounds can be converted to aromatic compounds with cyclobutene rings fused thereto, by pyrolysis. This is achieved by contacting the ortho chloroalkylated alkyl aromatic compound with at least 2 times its weight of a suitable diluent, and thereafter passing the mixture through a reactor at a temperature of 550°C or greater and a. pressure of between atmospheric and 25 mm of mercury (101.3 and 3.3 kPa). Suitable diluents are generally substituted aromatic compounds which are inert to the chloroalkylated alkyl aromatic compound and are stable at pyrolysis temperatures. Examples of suitable diluents are benzene, toluene, xylenes, chlorobenzenes, nitrobenzenes, met ylbenzoates, phenyl acetate or diphenyl acetate. Preferred diluents are the xylenes. Preferable temperatures are between 700°C and 750°C. Preferable pressures .are between 35 and 25 mm of mercury (4.7 and 3.3 kPa). In a preferred embodiment, the reaction mixture is passed through a hot tube packed with an inert material, for example, quartz chips or stainless steel helices. The product can be recovered by distillation. The product wherein the aromatic compound is benzene corresponds to the formula

wherein R, R and c are as hereinbefore defined.

In the preferred embodiment wherein R is a hydrocarbyloxy carbonyl moiety, the hydrocarbyloxy carbonyl moiety can be converted to a carboxylate moi¬ ety by contacting the substituted (arylcyclobutene) com¬ pound with at least a molar equivalent of alkali metal hydroxide in an alkanol-water solvent system. In the embodiment wherein the aromatic radical is benzene, the product corresponds to the formula

Thereafter the carboxylate-substituted (aryl¬ cyclobutene) compound can be converted to an acid chlo¬ ride by contacting the carboxylate-substituted (arylcy- clobutene) compound with thionyl chloride and refluxing at a temperature between 70°C to 80°C. The acid halide- -substituted (arylcyclobutene) so formed can be used to prepare the novel monomers of this invention, as described hereinafter. In the embodiment wherein the aryl radical is a benzene ring, the product corresponds to the formula

In an alternative synthesis, an aryl compound with ortho dibromomethyl groups can be converted to a 1,2- -diiodoarylcyclobutene, by contacting the aryl compound substituted with ortho dibromomethyl moieties with an 5 alkali metal iodide in an alkanol solvent at reflux so as to form the diiodoarylcyclobutenes. The product can be recovered by filtering, evaporating the filtrate and-.. recrystallizing the product. In the embodiment wherein the aryl radical is a benzene radical, the starting mate- 10. rial corresponds to the formula

and the iodobenzocyclobutene corresponds to the formula

The 1,2-diiodoarylcyclobutenes can be con- 20 verted to aryleyelobutenes by dissolving the 1,2-diiodo- arylcyclobutenes in an alcohol solvent, preferably metha- nol or ethanol and contacting the solution with an alkali . metal hydroxide in the presence of a palladium-on-carbon catalyst and H ₂ . gas at a temperature between 20°C and 25 30°C. In general, at least between 2 and 4 moles of alkali metal hydroxide per mole of 1,2-diiodoaryl- cyclobutene is used. Preferably, between 50 and 200 (0.35 and 1.38 MPa) psi of ydrogen gas is used. The arylcyclobutenes prepared in this manner can be

recovered by distillation. In the embodiment wherein the aryl radical is a benzene radical, the product corre¬ sponds to the formula

The arylcyclobutene can thereafter be bromi- nated. In this process, the arylcyclobutene is dissolved in acetic acid and contacted with a brominating agent of pyridinium perbromide hydrobromide in the presence of mer¬ curic salts, for example, mercuric acetate, at a tempera- ture of between about 20°C and 50°C. The brominated prod¬ uct can be recovered by extraction and distillation. In the embodiment wherein aryl radical is benzene, the prod¬ uct corresponds to the formula

The brominated arylcyclobutene can there¬ after be carbonylated to prepare a hydrocarbyloxy car- bonyl-substituted arylcyclobutene. This carbonylation is achieved by dissolving the brominated arylcyclobu¬ tene in an alkanol solvent, and thereafter contacting the solution with carbon monoxide under pressure ^" in' the presence of a palladium catalyst, wherein the pal¬ ladium is in the zero valence state, in the further presence of an acid acceptor under conditions such that the brominated arylcyclobutene compound undergoes car¬ bonylation. Preferred catalysts are complexes prepared

fro palladium acetate and triphenyl phosphine, palla¬ dium triphenyl phosphine tetrakis, and bis(triphenyl phos¬ phine) palladium chloride complex. The acid acceptor is generally a tertiary amine. In general, the reaction ves- sel is pressurized with carbon monoxide to a pressure of between atmospheric and 3000 psi (0.10 and 20.68 MPa), preferred pressures are between 600 and 1000 psi (4.'14 and 6.89 MPa).

This process is preferably performed at a temperature of between 100°C and 140°C, most preferably between 120°C and 130°C. The hydrocarbyloxy carbonyl arylcyclobutene can be recovered by filtering off the catalyst, washing away the acid scavenger with a 10 per¬ cent strong mineral acid solution, stripping off the sol- vent and distilling. To prepare a carboxamide-substi- tuted arylcyclobutene, a primary or secondary amine is substituted for the alcohol solvent. In the embodiment wherein the aryl radical is a benzene radical, the pro¬ cess corresponds to the following equation:

wherein R and c are as hereinbefore defined and R 2 and

R 3 are hydrocarbyl moi.eties. The hydrocarbyloxy carbonyl-

-substituted or carboxamide-substituted -arylcyclobutenes can thereafter be acidified and converted to acid chlo¬ rides by the process described hereinbefore.

The chlorocarbor^yl-substituted arylcyclobu¬ tene compounds can be converted to pol (arylcyclobutene)

compounds by contacting the halocarbonyl-substituted arylcyclobutenes with active hydrogen-containing com¬ pounds. Active hydrogen-containing compound refers herein to any compound which contains a hydrogen atom bonded to an oxygen, sulfur, phosphorus or nitrogen atom. For the purposes of this invention, an active hydrogen-containing compound refers to a compound con¬ taining a hydrogen atom which, because of its position in the molecule, displays significant activity accord- ing to the Zerewitnoff test described-by Woller in the J. Am. Che . Soc, 49, 3181 (1927). Illustrative of such active hydrogen moieties are -COOH, -OH, -NH ₂ , =NH, -CONH ₂ , -SH, and -CONH-. Such active hydrogen-contain¬ ing compounds include, for example, polyols, polyamines, polyimides, polymercaptans, and polyacids. To prepare a poly(arylcyclobutene) compound wherein the linking group is an amide, one contacts the halo carbonyl arylcyclobu¬ tene with a polyamine. To prepare a poly(arylcyclobu¬¬ tene) wherein the linking group is an imide, the active hydrogen-containing compound is a polyamide. To pre¬ pare a poly(arylcyclobutene) wherein the linking group is an ester, the active hydrogen-containing compound is an alcohol. To prepare a poly(arylcyclobutene) wherein the linking group is an anhydride, the active hydrogen- -containing compound is an acid. The active hydrogen- -containing compounds useful in this invention gener¬ ally correspond to the formula

^B * ^H >n

wherein B and n are as hereinbefore defined. More preferably the active hydrogen-containing compound cor¬ responds to the following formula

XfZ-H) n

wherein X, Z and n are as hereinbefore defined.

In another preparation of an arylcyclobu¬ tene, the reaction may follow that reported by Skorcz and Kaminski, Org. Syn. , 48, pages 53-56 (1968). In a typical preparation, an alkyl cyanoacetate is added to a solution of sodium metal in ethanol followed by the addition of an ortho-halomethylaryl halide. The alkyl 3-(0-haloaryl)-l-cyanopropionate is isolated and treated with aqueous sodium hydroxide. Subsequent acidification results in the cyanoacetic acid derivative. That deriva¬ tive is placed into N,N-dimethylformamide and is refluxed to form the 3-(0-haloaryl)propionitrile derivative which is isolated and added to a suspension of sodamide in liq- uid ammonia. After an appropriate reaction time, ammonium nitrate is added and the ammonia allowed to evaporate. The cyanoarylcyclobutene is isolated by ether extraction and purified by fractional distillation under reduced pressure.

Substituted aryleyelobutenes can be prepared by the same technique by using the appropriately substi¬ tuted reactants, such as an alkyl or alkoxybenzyl halide. Also substituents can result from using an alkyl haloace- tate, alkyl acetoacetate or a dialkylmalonate.

In another preparation based on the paper by

Matsura et al., Bull. Chem. Soc. Jap., 39, 1342 (1966), o-aminoaryl carboxylic acid is dissolved in ethanol and hydrochloric acid added. Isoamylnitrite is slowly added

to the cold stirred solution and diethyl ether is then added. The product, aryldiazonium-2-carboxylate hydro- chloride, is filtered. That product is placed in a sol¬ vent, preferably ethylene"dichloride, and acrylonitrile and propylene oxide is added to the stirred mixture which is then heated under nitrogen until the reaction is complete. After cooling, the mixture is filtered and the product, 1-cyanoarylcyclobuteήe, is isolated by frac¬ tionally distilling the filtrate under reduced pressure.

Amounts of reactants, reaction parameters and other details can be found in the cited article, the examples of this application, or can be easily deduced therefrom.

In a next sequence of reactions, the cyano- arylcyclobutene or substituted derivative is nuclear sub¬ stituted. When the poly(arylcyclobutene) to be prepared has an amide-linking group, the cyanoarylcyclobutene is aminated. In one preparation, the cyanoarylcyclobutene is added slowly to a cold solution of sodium nitrate in concentrated sulfuric acid to form 5-nitro-1-cyanoarylcy¬ clobutene. That nitro compound is isolated, dissolved in ethanol and reduced by hydrogenation over a palladium on carbon catalyst. The isolated product is 5-amino-l- -cyanoarylcyclobutene. In the preferred embodiment where the aryl radical is benzene, the product corresponds to the formula

In another method of preparing the poly(aryl¬ cyclobutene) monomers, the amino-substituted arylcyclo¬ butene is reacted with an appropriate coupling material. Coupling material refers herein to a compound which reacts with the amino or other substituent on the arylcyclobutene so as to form a bridging member with the amino or. other substituent. Such processes are described hereinafter. In the embodiment wherein the bridging member contains amide-linking ^" groups, the amino-substituted arylcyclo- butenes are reacted with a polyvalent acid chloride. In practice, the amine-substituted arylcyclobutene is dissolved in a chlorinated aliphatic hydrocarbon solvent to which is added a tertiary amine, the acid acceptor, and thereafter the polyvalent acid chloride in a chlori- nated aliphatic hydrocarbon solvent is added slowly to the mixture. This is preferably done at about 0°C in an inert atmosphere. It is preferred to stir the reac¬ tion mixture for a period of time at 0°C after the addi¬ tion is complete.

To prepare a hydroxy-substituted arylcyclo¬ butene, an amine-substituted arylcyclobutene is con¬ tacted with an alkali metal nitrite in the presence of sulfuric acid at 0°C, and thereafter the reaction mix¬ ture is heated to 100°C.

To prepare a mercapto-substituted arylcyclo¬ butene, first an arylcyclobutene is reacted with chloro- sulfonic acid to prepare an arylcyclobutene sulfonyl chloride. Aryleyelobutenyl sulfonyl chloride is reacted with zinc to prepare a mercapto-substituted arylcyclo- butene. Alternatively, the arylcyclobutene is treated

with a mixture of sulfur trioxide and dioxane at 0°C fol¬ lowed by treatment with water. The arylcyclobutene-sul- fonic acid is isolated and treated with phosphorous pen- tachloride to form the arylcyclobutene sulfonyl which is then reduced with zinc to the mercapto-substituted aryl¬ cyclobutene.

An iodo-substituted arylcyclobutene can be prepared by reacting an amino-substituted arylcyclobu¬ tene with an alkali metal nitrite, sulfuric acid and potassium iodide at 0°C under conditions such that an iodoarylcyclobutene is prepared.

An alkenyl-substituted arylcyclobutene can be prepared by reacting a bromo-substituted arylcyclo¬ butene with an alkene, wherein the alkene contains a terminal olefin, . in an aliphatic hydrocarbon solvent in the presence of a palladium catalyst such as pal¬ ladium acetate, and a tertiary amine such as triethyl- amine. It is advantageous to use a slight excess of the bromo-substituted arylcyclobutene. The tertiary amine, which functions as an acid acceptor, is used in equimolar amounts with the bromo-substituted aryl¬ cyclobutene. The palladium catalyst is used in cata- lytically effective amounts. Generally this process can be performed at temperatures of between 40°C and 140°C.

To prepare a poly(arylcyclobutene) with an alkene-poly-yl or alkenar-poly-yl-bridging member, an alkene or alkene-substituted aromatic compound which contains two or more terminal olefinic moieties is reacted with at least one more of a bromo-substituted arylcyclobutene for each terminal olefin under condi¬ tions described hereinbefore.

To prepare a poly(arylcyclobutene) monomer in which the bridging member contains an amine-linking group, the amine-substituted arylcyclobutene is reacted with a polyvalent alkyl halide. In order to prepare a poly(arylcyclobutene) monomer in which the bridging mem¬ ber contains a linking group which is ureylene, the amine- -substituted arylcyclobutene is reacted with a polyvalent isocyanate or phosgene.

To prepare a poly(arylcyclobutene) monomer in which the bridging member contains a linking group of a cyclic imide, the amine-substituted arylcyclobu¬ tene is reacted with a polyw ^r alent anhydride compound.

To prepare a poly(arylcyclobutene) monomer with a polyvalent organic bridging member containing carbonyl-linking groups, the arylcyclobutene is reacted with an acid chloride with two or more acid chloride moieties, in the presence of aluminum chloride.

To prepare a poly(arylcyclobutene) monomer with a polyvalent organic bridging member containing an ammonium carboxylate-linking group, a carboxylate-substi¬ tuted arylcyclobutene is contacted with a polyvalent polyamine-substituted compound.

To prepare a poly(arylcyclobutene) with a polyvalent organic bridging member containing thio-link- ing groups, a mercapto-substituted arylcyclobutene is reacted with an alkali metal hydroxide to prepare an alkali metal salt of the mercapto-substituted arylcy¬ clobutene. The salt is then reacted with a polyhalo organic compound to prepare a poly(arylcyclobutene) with an organic bridging member containing thio-link- ing groups.

To prepare a poly(arylcyclobutene) with a polyvalent organic bridging member containing nitrogen (amino)-linking groups, two or more equivalents of an amino-substituted arylcyclobutene are reacted with an organic compound containing two or more aldehyde moi¬ eties in the presence of an alkali metal cyanoborohy- dride under conditions that a poly(arylcyclobutene) with a polyvalent organic bridging member with amino- -linking moieties is prepared. One equivalent of amino- -substituted arylcyclobutene for each aldehyde moiety on the organic aldehyde-containing compound is used. Alternatively, two or more equivalents of amine-substi¬ tuted arylcyclobutene are reacted with an organic com¬ pound containing two or more bromo moieties in the presence of an alkaline earth metal carbonate under conditions such that a poly(arylcyclobutene) with an organic bridging member containing amino-linking moi¬ eties is prepared. An equivalent of amino-substituted arylcyclobutene is used for each bromo moiety on the bromo-substituted organic compound.

To prepare poly(arylcyclobutene) monomers with polyvalent organic bridging members containing oxygen-linking moieties, a hydroxy-substituted arylcy¬ clobutene is contacted with an alkali metal hydroxide to prepare an alkali metal salt of a hydroxy-substi- tuted arylcyclobutene. Two or more equivalents of the salt is then reacted with an organic compound contain¬ ing two or more bromo moieties, under conditions such that a poly(arylcyclobutene) with an organic bridging member containing oxygen-linking groups is prepared. One equivalent of the salt for each bromo moiety on the organic compound is used.

An alternative method of preparing the poly-

(arylcyclobutene) monomers wherein a carbonyl group is attached to the aryl moiety involves contacting the car¬ boxylate-substituted arylcyclobutenes with 1' ,1-carbonyl- diimidazole in an ether solvent at 0°C. The reaction mixture is then heated until it reaches the reflux of the solvent and thereafter any active hydrogen-contain¬ ing compound is added so as to prepare a poly(arylcyclo¬ butene) monomer, wherein the bridging member contains a carbonyl group which is bonded to the aryl group of the arylcyclobutene.

In order to prepare a polysiloxane bridging member, the amino-substituted arylcyclobutene is reacted with a polychlorinated polysiloxane. Alternatively, a halocarbonyl-substituted arylcyclobutene is reacted with an aminoalkyl-terminated polysiloxane.

To prepare a poly(arylcyclobutene) monomer with a polyvalent inorganic bridging member comprising a carbonyl moiety, an acid-halide-substituted (arylcy- clobutene) is reacted with an arylcyclobutene in the presence of A1C1 ₃ or SnCl ₄ -

To prepare a poly(arylcyclobutene) with a carbonyldioxy inorganic bridging member, two moles of a hydroxy-substituted arylcyclobutene is reacted with phosgene in the presence of a tertiary amine. To pre¬ pare a poly(arylcyclobutene) with a bridging member of a polyvalent metal ionically bonded to a polyvalent carboxylate moiety, a carboxylate-substituted arylcy¬ clobutene is reacted with a metal hydroxide to prepare a metal poly(arylcyclobutene) carboxylate. In general, the metal hydroxide is reacted with the number of moles

of carboxylate-substituted arylcyclobutenes equal to the metal's coordination number. A poly(arylcyclobutene) with a polyvalent metal bridging member is prepared by first reacting one equivalent of a bromine-substituted arylcyclobutene with one equivalent of magnesium in an ether solvent to prepare an arylcyclobutenyl magnesium bromide. To prepare a di(arylcyclobutenyl) magnesium, one equivalent of a brominated arylcyclobutene is reacted with two equivalents of magnesium. The arylcyclobutenyl magnesium bromide is reacted with a metal chloride to prepare a poly(arylcyclobutenyl) metal. The metal chlo¬ ride is reacted with the number of equivalents of aryl¬ cyclobutenyl magnesium bromide equal to the metal's oxi¬ dation state.

To prepare a poly(arylcyclobutene) with an inorganic bridging member of sulfur, a mercapto-substi¬ tuted benzocyclobutene is reacted with an iodo-substi- tuted arylcyclobutene in an amide solvent in the pres¬ ence of an alkali metal hydroxide. Alternatively, the mercapto-substituted arylcyclobutene can be reacted with cuprous chloride to prepare a cuprous salt of a mercapto-substituted arylcyclobutene. The salt can thereafter be reacted with an iodo-substituted cyclo¬ butene in an amide solvent to prepare a pol (arylcyclo- butene) with a sulfide bridging member. The sulfide bridging member can be converted to a sulfoxide by con¬ tacting the poly(arylcyclobutene) sulfide with one equiva¬ lent of peracetic acid under conditions to oxidize the sulfide to a sulfoxide. Alternatively, the sulfide can be converted to a sulfone by contacting the poly(arylcy¬ clobutene) with two equivalents of peracetic acid under conditions to oxidize the sulfide to a sulfone.

To prepare a poly(arylcyclobutene) with a phosphorus bridging member, an arylcyclobutene magnesium bromide is reacted with phosphorus trichloride to pre¬ pare a tri(arylcyclobutenyl) phosphine. The tri(arylcy- clobutenyl) phosphine can be contacted with peracetic acid, so as to prepare a tri(arylcyclobutenyl) phosphine oxide.

To prepare a poly(arylcyclobutene) with a nitrogen bridging member, an amino-substituted aryl- cyclobutene is reacted with a potassium hydride to pre¬ pare a potassium salt of an amine-substituted arylcyclo¬ butene. The salt is then reacted with an iodoarylcyclo- butene in liquid ammonia under ultraviolet light, under conditions that a poly(arylcyclobutene) with a nitrogen bridging member is prepared.

To prepare a poly(arylcyclobutene) with an oxygen bridging member, two equivalents of a hydroxy- -substituted arylcyclobutene are reacted with cupric carbonate to prepare cupric salt comprising a copper cation and two anions of hydroxyarylcyclobutenes from which the hydroxyl hydrogens have been abstracted. The salt is then reacted with an iodoarylcyclobutene, at between 100°C and 180°C, either neat or in an amide solvent, under conditions such that a di(aryleyelobu- tene) ether is prepared.

The novel poly(arylcyclobutene) compounds of this invention are useful in the preparation of poly¬ meric compositions. In general, these polymeric compo¬ sitions are prepared by contacting one or more of the poly(arylcyclobutene) compounds and heating them to the polymerization temperature of the particular monomer(s)

used. The polymerization is an addition polymerization wherein no volatiles are generated. Furthermore, no catalyst initiator or curing agents are necessary for the polymerization to take place. It is believed that the polymerization takes place when the cyclobutene ring undergoes transformation to prepare a molecule containing a 1,3-cyclohexadienyl radical with two exo-olefinic unsat¬ urated moieties adjacent to one another wherein each of the olefinic unsaturated moieties undergoes reaction with the olefinic unsaturated moieties of other 1,3-cy- clohexadienyl-containing molecules which have undergone the same transformation. The temperature at which the poly(arylcyclobutene) monomers undergo polymerization is affected by the nature of any substituent on the cyclobu- tene ring. In some embodiments, the temperature of polym¬ erization is as low as about 30°C. In preferred embodi¬ ments, the temperature at which polymerization is initi¬ ated is above 150°C, more preferably above 200°C. It is to be noted that the temperature at which polymer- ization is initiated is dependent upon the nature of sub¬ stituents on the cyclobutene ring. In general, wherein the cyclobutene ring is unsubstituted, the polymeriza¬ tion is initiated at about 200°C. Wherein the cyclobu¬ tene ring is substituted with an electron-donating sub- stituent, the polymerization temperature is generally lowered, the higher the ability of the substituent to donate electrons, the lower the polymerization initia¬ tion temperature is. Conversely, the electron-with¬ drawing substituents on the cyclobutene ring result in higher polymerization initiation temperatures. The unsubstituted cyclobutene in general polymerizes at the highest temperature.

It is believed the polymers prepared from the poly(arylcyclobutenes) comprise units correspond¬ ing to the formulas

and

or mixtures thereof. It is believed that the preferred polymers prepared from the poly(arylcyclobutenes) com¬ prise mixtures of formulas A and B.

In those embodiments wherein Ar is benzene, it is believed that the polymer's prepared from poly(ben- zocyclobutenes) comprise units corresponding to the for¬ mulas

and

or mixtures thereof. It is believed the preferred polymers prepared comprise mixtures of formulas C and D with D being.predominant.

The method of polymerization of the poly- (arylcyclobutene) monomers has a significant effect on the nature and properties of the polymeric composition prepared. In one embodiment, the poly(arylcyclobutene) monomers of this invention can be melt polymerized. The

melt pol _y merization of poly(arylcyclobutene) monomers allows their use in the preparation of solid parts, as coatings, in composites, as adhesives and as fibers.

Suitable fillers and reinforcing materials are, generally, in any powder form and/or fibrous prod¬ ucts, for example, of the type commonly used in the pro¬ duction of moldings based on unsaturated polyester resins or epoxide resins. Examples of products such as these are, primarily, granular fillers such-as quartz powder, ground shale, asbestos powder, powdered carborundum, chalk, iron powder, aluminum powder, sand, gravel and other fillers of this kind, also inorganic or organic fibers, more especially glass fibers in the usual tex¬ tile forms of fibers, filaments rovings, yars, nonwovens, mats and cloths. In this connection, amino silane-

-based finishes have proven to be particularly effective. It is also possible to use corresponding textile struc¬ tures of organic, preferably synthetic fibers (polyamides, polyesters) or on the basis of quartz, carbon, metals, etc., as well as monocrystals (whiskers).

The end products combined with fillers or reinforcing materials may be used in particular in ves¬ sel and pipe construction by the winding technique, in electrical engineering, in mold construction and tool making and also in the construction of heavily stressed components, in the lightweight construction of vehicles in aeronautical and astronautical engineering.

In another embodiment, the poly(arylcyclobu¬ tene) monomers of this invention can be used to prepare coatings and films. In one embodiment, the monomers are dissolved in a suitable solvent and coated onto the

substrate of choice, and thereafter the coated substrate is exposed to temperatures of above the polymerization temperature of the monomer. Preferably, the polymeriza¬ tion temperature is 150°C or above, more preferably 200°C or above. The coated substance is exposed to polymeriza¬ tion temperatures for a sufficient time for the polymeri¬ zation to be completed. Preferably, such exposure times are between 1 and 5 hours. Suitable solvents are those which volatilize away at temperatures below the polymeri- zation temperature. Preferred solvents are cyclic and aliphatic ethers, lower alkanols, amides, and chlorinated hydrocarbon solvents. It is preferable to saturate the solvent with the monomer, a 20 to 30 weight percent con¬ centration of monomer in the solvent is more preferred.

The poly(arylcyclobutene) monomers may be com¬ bined with the powder-form or fibrous fillers or reinforc¬ ing materials either before or after heat treatment. For example, it is possible to impregnate powder-form or fibrous fillers or reinforcing materials such as quartz sand or glass cloths, with the poly(arylcyclobutene) monomers, optionally in solution.

In another embodiment, a film can be pre¬ pared from the poly(arylcyclobutene) monomers of this invention by powder coating techniques. In particular, the monomer in a powder form is placed on a desired substrate. Thereafter, the monomer is heated to its melt temperature over a time sufficient to melt the monomer and allow the melted monomer to form a liquid coating on the substrate. Thereafter, the melted mono- mer coated on the substrate is exposed to temperatures at which the monomer polymerizes for a time sufficient for the monomer to form a film on the desired substrate.

In one embodiment, the poly(arylcyclobutene) monomers can be formed into a prepolymer which thereafter can be polymerized. To form the prepolymer, the poly(aryl¬ cyclobutene) monomers are contacted in an inert atmosphere or under vacuum and heated to a stage at which the polym¬ erization mixture is sufficiently viscous enough to be moldable in conventional molding equipment. Preferably, the monomers can be contacted at a temperature between 190°C and 220°C for between 1 and 10 minutes. Thereafter, the prepolymer can be used in various techniques to pre¬ pare the polymeric compositions of this invention. In one preferred embodiment, the prepolymer is cooled to form a powder which can be used to form compression molded articles, as an adhesive, and in many other uses.

In another embodiment, a prepolymer of the poly(arylcyclobutene) monomers can be prepared by pre¬ cipitation polymerization. In particular, the technique involves heating such monomers in a solvent to prepare a , low molecular weight prepolymer. A solvent is used which dissolves the monomer but not the prepolymer. As the pre¬ polymer forms, it precipitates and is removed. The pre¬ polymer can be fabricated in a hot compression mold which reacts out the remaining arylcyclobutene rings to give a thermoset polymer. The product is a fine white powder. Preferable solvents are nonpolar solvents, such as aro¬ matic hydrocarbons, aliphatic hydrocarbons, aliphatic chlorinated hydrocarbons, aromatic chlorinated hydrocar¬ bon solvents, biphenols, naphthalenes or polychlorinated biphenyls. In general, the monomer can be dissolved up to saturation in the solvent used. A 20 to 30 percent by weight solution of the monomer in the solvent is pre¬ ferred. The prepolymer is used to prepare a polymer by

heating the prepolymer in the desired form, to the polym¬ erization temperature of the monomer for a time suffi¬ cient for the polymerization to go to completion.

The polymerization preferably takes place at temperatures of between 200°C and 240°C for periods of between 1 and 5 hours.

In another embodiment, the poly(arylcyclobu¬ tene) monomers can be polymerized by solution polymeri¬ zation techniques. In this embodiment, the monomers are dissolved in dipolar aprotic solvents with boiling points above the polymerization temperature of the mono¬ mers. It is preferable that the solvents have a boil¬ ing point of near or above 200°C and more preferable that the solvents have a boiling point of above 250°C. Examples of preferred dipolar aprotic solvents include amides and sulfones. It is necessary to add to the solution lithium salts which solubilize the polymer in the solvents, preferably, between 5 and 20 weight percent based on the solvent weight. A preferred lith- ium salt is lithium chloride. The polymerization takes place by heating the polymerization solution to a tem¬ perature at which the monomer undergoes polymerization, preferably 200°C. The polymerization time is preferably between about 1 and 10 hours. The polymer can be recovered by adding water to precipitate the polymer from the reaction solution and thereafter stripping off the solvent. The polymers prepared with this method can be used in compression moldings or to prepare coatings.

In another embodiment, the monomers of this invention which undergo polymerization at a temperature which is below the melting point of the monomer can be polymerized in a solid state polymerization. In this method, the monomer is heated to a temperature at which polymerization takes place. Polymers prepared in this method can be useful in the preparation of bearings, seals and other parts by powder metallurgy techniques.

The following preparations of intermediate compounds and examples are included for illustrative purposes only, and do not limit the scope of the inven¬ tion or the claims. Unless otherwise specified, all parts and percentages are by weight.

Chloromethylation of Methyl Para-toluate A solution of methyl para-toluate (30 g, 0.20 mole) in 1,2-dichloroethane (80 ml) is added to a flask equipped with ice bath, stirrer, water-cooled condenser, ice traps and scrubber. To the stirred solution is added chloromethyl methyl ether (48 ml, 0.63 mole), thionyl chlo- ride (5.8 ml, 0.080 mole), and last ferric chloride (6.5 g, 0.040 mole) in two portions. The cooling bath is removed, and the stirred reaction mixture is heated at 60°C (heat¬ ing lamp, controller) for 3 hours.

Methanol (150 ml) is added gradually to the cooled reaction mixture (exotherm). Low boiling com¬ ponents are removed under vacuum. The solution of prod¬ uct in dichloroethane is washed with water, 5 percent sodium bicarbonate solution, dried over anhydrous mag¬ nesium sulfate, filtered, and solvent is removed under vacuum. The product contains 13 percent unreacted methyl

para-toluate and 80 percent methyl 3-chloromethyl-4-meth- ylbenzoate (CMMT-chloromethylated methyl toluate) as ana¬ lyzed by capillary gas chromatography. Recovery of the starting material by vacuum distillation affords a dis- tillation residue of 91 percent pure product (analysis by capillary gas chromatography).

Pyrolysis of Methyl(3-chloromethyl)para-toluate to Prepare 4-carbomethoxybenzocyclobutene

The experimental apparatus is a quartz tube packed with quartz chips. The central portion of the tube is placed in a furnace. A 25-centimeter portion of the tube above the furnace serves as a preheating zone and the temperature in the middle of such preheat¬ ing zone is between 250°C and 300°C. Attached to the top of the tube is an addition funnel. Attached to the bottom portion of the tube are cold traps and a means for pulling a vacuum on the tube. Methyl(3-chloromethyl)- para-toluate (50 g) is dissolved in 200 g of ortho-xylene and placed in the addition funnel. The furnace is heated up to 730°C. A vacuum pump is turned on and pressure is adjusted to 25 ml of mercury (3.3 kPa). The solution of methyl(3—chloromethyl)para-toluate is added dropwise over a period of 1 hour and 15 minutes. Product and unreacted starting material are collected in cold traps. The pyrolytic tube is flushed with 200 ml of acetone after a cooling down period. The acetone solution is combined with the ortho-xylene solution collected in the cold traps. Acetone and ortho-xylene are distilled off with a 16-inch (406 mm) Vigreaux column under normal pressure. When most of the ortho-xylene is distilled, the system is brought to 0.02 mm mercury (2.7 Pa) and 15.5 g of pure 4-carbomethoxy-benzocyclobutene is collected at 61°C.

The residue left in the distillation pot is methyl-

(3-chloromethyl)para-toluate, 23 g.

Preparation of 1-cyanobenzocyclobutene

A mixture of benzenediazonium-2-carboxylate hydrochloride (1.92 g), acrylonitrile (0.80 g) and pro- pylene oxide (0.58 g) in 100 ml of ethylene dichloride is stirred in a flask under nitrogen at a temperature between 50°C-60°C for 4 hours. The mixture is cooled to room temperature and filtered. The filtrate is examined by gas chromatography and is found to contain 0.52 g (40 percent yield) of 1-cyanobenzocyclobutene.

Preparation of 5-amino-l-cyanobenzocyclobutene

The 1-cyanobenzocyclobutene is added slowly to a cold solution of sodium nitrate in cold sulfuric acid. The so-formed nitro compound is isolated, dis¬ solved in ethanol, and reduced by hydrogenation over a palladium on carbon catalyst.

Bromination of Benzocyclobutene

The brominating agent used in this case is pyridinium hydrobromide perbromide (C-.H-.N ΘHBr ₃ θ, for¬ mula weight 319.86). This reagent is prepared just prior to its use via the method of Fieser, Reagents for Organic Synthesis, Fieser & Fieser, pp. 967-982.

A 2000-ml round-bottom, three-neck flask is equipped with a reflux condenser connected to a nitrogen line with T and mineral oil bubbler, mechanical stirrer, and a thermocouple attached to, a temperature controller. The flask is then charged with 4.5 g of mercuric ace¬ tate (Hg(0 ₂ CCH ₃ ) ₂ , f.w. 318.68, 14.12 mmoles), 28.5 g of

benzocyclobutene (C _g H _g , m.w. = 104.15, 0.274 mole), and 950 ml of glacial acetic acid. This mixture is stirred, 60 g of pyridinium hydrobromide perbromide is added, and the reaction is heated to 50°C. After 4 hours, another 60 g of brominating agent is added. The mixture is sam¬ pled and the conversion of starting material to product is monitored by gas chromatography. The addition of 60-g increments of brominating agent proceeds in this manner until conversion is complete (4 days, 460 g of pyridin- ium hydrobromide perbromide total).

The reaction product is isolated by first decanting the acetic acid solution into a separatory funnel and diluting with 500 ml of water. The crystals of pyridinium hydrobromide perbromide are then soaked in methylene chloride (250 ml) to leach out any residual product. This methylene chloride solution is decanted into the separatory funnel, the funnel shaken, and the layers separated. The aqueous solution is returned to the funnel and the process is repeated twice more. The methylene chloride extracts are combined and washed with 500 ml of N ₂ S0 ₃ (5 percent), 500 ml of water, 500 ml of aqueous hydrochloric acid (10 percent), 500 ml of water, 500 ml of NaHC0 ₃ (saturated), 500 ml of water, and dried over MgS0 ₄ . The methylene chloride is then carefully removed via distillation, and the product is isolated by vacuum distillation using a column packed with stainless steel mesh. Bromobenzocyclobutene is collected at 58°C- -60°C with a vacuum of 1.5 mm Hg (200 Pa). Total of 32.8 g is isolated pure, and the pot residue contains another 8 to 10 g of material. Isolated yield is 65.6 percent of theoretical value.

Carbonylation of Bromobenzocyclobutene to Prepare Carbomethoxybenzocyclobutene

This reaction is run in a 450-ml Parr pres¬ sure reactor fitted with a magnetically coupled stirring system. Into this reactor is entered 30 g of bromobenzo¬ cyclobutene (0.164 mole), 16.5 g of (CH-CH^-N (0.164 mole, freshly distilled over Na metal), 100 ml of CHgOH (Burdick & Jackson brand), and the catalyst mixture of 1.1 g of Pd(0 ₂ CCH ₃ ) ₂ (4.9 mmoles, 3 mole percent) and 1.1 g of PPh ₃ (recrystallized from ethanol). The reac¬ tor is then sealed and attached to a CO cylinder. The mixture is purged with 600 psig (80.0 kPa gage) CO three times while stirring, and finally pressurized and held at 600 psig (80.0 kPa gage) CO. The tempera- ture is raised to 125°C, and held under these condi¬ tions overnight (approximately 16 hours). After this time, the unreacted CO is vented, and the reaction vessel is cooled to ambient temperature. The methanol solution is diluted with 200 ml of water, and the pro- duct extracted with 3 x 150 ml of CH ₂ C1 ₂ . The methyl¬ ene chloride solution is then washed with 250 ml of water, 250 ml of HCl (5 percent), 250 ml of water, 250 ml of NaHC0 ₃ (saturated), 250 ml of water, and dried over MgS0 ₄ . The methylene chloride solution is checked for conversion by gas chromatographic analysis, and the composition is discovered to be 97 percent 4-car- bomethoxybenzocyclobutene. The solvent is then removed by distillation, and the product is then purified by vacuum distillation at 66°C-67°C, 1 mm Hg vacuum (133 Pa).

Preparation of Benzocyclobutene 4-carboxylic Acid by Hydrolysis of 4-carbomethoxybenzocyclobutene

A 500-ml round-bottom, single-neck flask is equipped with magnetic stirrer and reflux condenser attached to a nitrogen line with T mineral oil bubbler.

To this flask is added 10 g of 4-carbomethoxybenzocyclo- butene (m.w. 162.19 g, 0.062 mole) and 190 ml of methyl alcohol (Burdick & Jackson brand). This solution is stirred, and to it is added 60 ml of aqueous NaOH solu- tion containing 7.5 g of NaOH (m.w. 39.998, 0.188 moles). This mixture is stirred at room temperature for one hour, after which the solution is transferred into a 1000-ml separatory funnel. The strongly alkaline solution is first diluted with 250 ml of water, and washed with 250 ml of CH ₂ C1 ₂ . The aqueous solution is then drained into a large beaker and acidified with concentrated HC1 until the solution is strongly acidic. The acid, which forms a white precipitate upon acidification, is then collected with 3 x 250 ml of CH ₂ C1 ₂ . The methylene chloride solu- tion is dried over MgS0 ₄ and the solvent removed via rotary evaporation. The carboxylic acid (8.95 g) is recovered as a white solid (98 percent of theoretical yield).

Preparation of Benzocyclobutene Acid Chloride 4-Carbomethoxybenzocyclobutene (29.2 g) is hydrolyzed to benzocyclobutene-4 carboxylic acid using the procedure given under Example 8. The acid is dried and added to 50 ml of freshly distilled thionyl chloride in a 500-ml single-neck flask equipped with a reflux con- denser, nitrogen blanket and magnetic stirrer. The mix¬ ture is refluxed under nitrogen for hour. The excess thionyl chloride is removed with a vacuum pump leaving the so produced acid chloride as a brown oil. The prod¬ uct weighs 28.6 g and is used without further purifica- tion.

Example 1 - Reaction of Benzocyclobutene Acid Chloride

With Heptamethylene Diamine

The acid chloride is dissolved in 100 ml of meth¬ ylene chloride and added to a 2-liter three-neck flask equipped with a thermometer port (the 2-liter flask and accessories are dried with a heat gun prior to adding the acid chloride). The flask is then equipped with a reflux condenser topped with a nitrogen line and mineral oil bubbler, an addition funnel fitted with a septum and a thermocouple probe placed in the thermometer port. Tri- ethylamine (20 g) is then added to the flask. Heptameth¬ ylene diamine (10.6 g) is weighed out into a bottle in a dry box and the bottle capped with a septum. The diamine is diluted with 100 ml of methylene chloride and trans- ferred via a syringe to the addition funnel. The diamine solution is then added dropwise to the reaction mixture. After this addition, the addition funnel is filled with methylene chloride and this is also added to the reaction mixture. This rinsing procedure is then repeated a sec- ond time. Finally, the reaction mixture is heated at reflux for 16 hours. The mixture is cooled to room tem¬ perature and poured into a separatory funnel. The mix¬ ture is then washed successively with 500 ml of water, 500 ml of 5 percent hydrochloric acid, 500 ml of water, 500 ml of saturated sodium bicarbonate and finally dried over anhydrous magnesium sulfate. The methylene chloride is evaporated off to give the product as a light brown solid. This is diluted with 250 ml of tolu¬ ene and heated. The solution is then filtered (after cooling for 15 minutes) and the solid removed through this filtration is again dissolved in 250 ml of tolu¬ ene. This solution is also heated, cooled for 15 min¬ utes and filtered (suction). The solid removed by this

filtration shows no coloration upon dilution with tolu¬ ene so the solid is removed by suction filtration and dried in vacuo. The final weight of the product is 24.58 g resulting in a 77.2 percent yield based on the amount of diamine added.

Example 2 - Preparation of diamide monomers

wherein n is the number of carbons between the car- boxyl groups.

(a) n = 2

5-Amino-l-cyanobenzocyclobutene (hereinafter called Compound A) (12.58 g, 0.089 mole) and triethyl- amine (7.05 g, 0.07 mole) are dissolved in 300 ml of methylene chloride. The solution is cooled to 0°C in an ice bath, with stirring unger argon. A solution of 6.91 g (0.045 mole) of succinyϊ chloride in 100 ml of methylene chloride is added dropwise to the cooled solu- tion. The reaction mixture is stirred for 30 minutes at 0°C after the addition is complete. The reaction mixture is then warmed to room temperature and is poured into 400 ml of water. The mixture is extracted 3 times with 250-ml portions of methylene chloride. The combined methylene chloride extracts are washed once with 400 ml ^* of a 5 per¬ cent hydrochloric acid solution. The methylene chloride layer is- washed with 400 ml of water. Next, the methyl¬ ene chloride solution is washed with 400 ml of saturated sodium bicarbonate and finally with 400 ml of water. The methylene chloride is removed under vacuum to give

the product as a gray solid. Yield is 10 g or 60.6 per¬ cent.

(b) n = 3

This monomer is prepared as under (a) using different amounts of reactants and is run in a nitrogen atmosphere. Compound A (12.13 g, 0.086 mole) and tri¬ ethylamme (8.7 g, 0.086 mole) are dissolved in 300 ml of methylene chloride. Glutaryl chloride (6.61 g, 0.038 mole) is dissolved- in 100 ml of methylene chloride and is added dropwise to the reaction mixture. The reaction is run and worked up the same as under (a) except that the methylene chloride solution is dried over anhydrous magnesium sulfate, filtered and then concentrated under vacuum. The product is a green solid. The yield is 13 g, 86.6 percent.

(c) n = 4

This monomer is prepared in the same manner as described in (a) using different amounts of reactants and is run in a nitrogen atmosphere. Compound A (11.7 g, 0.083 mole) and triethylamine (8.4 g, 0.083 mole) are dis¬ solved in 300 ml of methylene chloride. Adipoyl chloride (6.90 g, 0.038 mole) is dissolved in 100 ml of methylene chloride and is added dropwise to the mixture. The workup of the reaction mixture is the same as under (b), obtain- ing 14.7 g (98 percent) of a white solid.

The product is recrystallized from ethanol to give 8 g (53.3 percent yield) of solid.

( d) n = 5

Thionyl chloride (5.12 g, 0.043 mole) is added dropwise under nitrogen to 20 ml of dry N,N-di- methylformamide which is cooled and stirred for 30 min- utes at 0°C in an ice bath. Pimelic acid (3.20 g, 0.020 mole) is dissolved in 15 ml of dry N,N-dimethylformamide and is added dropwise to the cooled reaction mixture. The reaction mixture is stirred an additional 30" minutes and then is warmed to room temperature and is stirred another 30 minutes, then again is cooled to 0°C in an ice bath. Compound A (6.77 g, 0.047 mole) and triethyl- amine (6.06 g, 0.060 mole) are dissolved in 20 ml of dry N,N-dimethylformamide. This solution is then added dropwise to the cooled reaction mixture. The reaction mixture is slowly warmed to room temperature overnight. The reaction mixture is poured into 500 ml of water and is stirred for 30 minutes. Next, the water layer is extracted then washed twice with 200-ml portions of chlo¬ roform. The chloroform washes are combined and washed once with 300 ml of a saturated sodium bicarbonate solu¬ tion, and once with 300 ml of water. The chloroform solu¬ tion is washed once with 300 ml of a 10 percent hydrochlo¬ ric acid solution and finally with 300 ml of water. The chloroform solution is then dried over anhydrous magne- sium sulfate, filtered and concentrated under vacuum.

The product obtained is column chromatographed over sil¬ ica gel using ethyl acetate as the eluting solvent. A yellow colored solid is obtained.

(e) n = 6 This monomer is prepared by the same procedure that is used under (d) except that 0.02 mole suberic acid was employed, and 0.048 mole of Compound A and 0.061 mole of triethylamine are dissolved in 15 ml of N,N-dimethyl- formamide and are added to the cooled reaction mixture. A white solid is obtained.

(f) n = 7

This monomer is prepared by the method used under (d). Thionyl chloride (4.53 g, 0.038 mole) is added while stirring to 20 ml of dry N,N-dimethylforma- mide. Azelaic acid (3.33 g, 0.018 mole) is dissolved in 15 ml of N,N-dimeth Iformamide and is added to the reaction mixture at 0°C. The reaction mixture is then stirred as indicated previously under (d). Compound A (6.0 g, 0.042 mole) and triethylamine (5.37 g, 0.053 mole) are dissolved in 15 ml of N,N-dimethylformamide and added dropwise to the cooled reaction which is worked up as in (d), obtaining a brown solid.

(g) n = 8

This preparation involves dissolving Com- pound A (1.41 g, 0.01 mole) and pyridine (1.0 g, 0.013 mole) in 35 ml of methylene chloride. This solution is cooled to 0°C in an ice bath with stirring under nitrogen. Sebacoyl chloride (1.20 g, 0.005 mole) is dissolved in 15 ml of methylene chloride and is added dropwise to the cooled solution. The reaction mixture is stirred for 30 minutes at 0°C and is warmed to room temperature. The reaction mixture is poured into 100 ml of water and is extracted 3 times with ^' 50-ml portions of methylene chloride. The methylene chloride extracts are combined and washed once with 100 ml of a 5 percent hydrochloric acid solution. The methylene chloride solu¬ tion is then washed with 100 ml of water and is dried over anhydrous magnesium sulfate. The solution is fil¬ tered and concentrated under vacuum to obtain a white- -colored solid. The solid product is dried under a vacuum overnight.

The monomers prepared above are tested for melting temperature and polymerization temperature as indicated by the onset and peak exotherm temperature as measured by differential scanning colorimetry (DSC)

The results are in the following table:

Monomer Melting

Point Polymerization Temperature (°C) n (°C) DSC Onset DSC Peak

2 >245 195 209

3 121 175 202

4 173 182 203

5 60 189 213

6 157 185 213

7 61 183 214

8 171 overlaps M.P. 206

For melt polymerization it is preferable that the monomer melt at a much lower temperature than that at which it polymerizes and that polymerization occurs by elevating the temperature of the melt. For that purpose, the monomers where n is an odd number are preferred.

The temperature at which polymerization begins and the maximum temperature of polymerization are relatively unaffected by the size of n. The poly¬ mers show comparable thermal stability at 400°C.

Into a 10-ml, round-bottom flask connected to a vacuum line is placed 2.5 g of the powdered monomer of (g) n = 8. The flask is evacuated and is immersed in a Woods metal bath at 90°C. The temperature is slowly raised to 250°C over one hour and is held at that tempera¬ ture for 15 minutes. The flask is then cooled and broken open to remove the solid block of polymer.

One gram of the monomer of (g) n = 8 is dissolved in 15 ml of N,N-dimethylformamide and is coated on Bonderite 1000 treated steel panels with a 0.010 inch (0254 mm) draw bar. The panels are then air dried at room temperature for 1 hours. Final traces of solvent are removed by heating in a vacuum oven at 70°C for one hour. The monomer coated plates are then heated in an air oven at 250°C for one hour to effect polymerization. The polymer coating is brown, glossy, flexible and exhibits a Knoop hardness of 37.

A monomer (0.5 g) prepared by the method described in (g) n = 8 is dissolved in 2 ml of dimethyl sulfoxide. The solution is coated onto alu¬ minum plates with a 0.010 (0.254 mm) inch draw bar. The plate is placed in an air oven at 250°C for one hour. The polymer coating which is formed is smooth, glossy, dark amber in color, has a Knoop hardness of 34 and the plate can be bent 90° without cracking the coating. The coating is only slightly swollen by immer¬ sion in dimethyl sulfoxide overnight. The coating is mechanically peeled off of one aluminum plate to give a flexible film of 0.00.1 (0.0254 mm) inch thickness. The film has a tensile strength of 12,000 psi (82.7 MPa) at room temperature and a 5 percent elonga¬ tion at break. The tensile modulus is 350,000 psi

(2.41 GPa). The film demonstrates no failure after cycling it under 6,000 to 8,000 psi (41 to 55 MPa) load for 100 cycles at room temperature.

Example 3 - Preparation of bisbenzocyclobutene with a diamido bridging member

The general reaction sequence is to react benzocyclobutene 4-carboxylic acid with 1,1-carbonyl diimidazole to give an imidazole derivative which is further reacted with a polyalkyene diamine to result in the bis-amide monomer.

(a) n = 3 1,1-Carbonyldiimidazole (2.64 g, 0.016 mole) is dissolved in 45 ml of dry tetrahydrofuran and stirred under nitrogen at room temperature. The benzocyclobutene 4-carboxylic acid (2.37 g, 0.016 mole) is dissolved in 45 ml of dry tetrahydrofuran and added dropwise to the stirred imidazole solution at room temperature. The mix¬ ture is stirred for 30 minutes at room temperature and then heated at reflux overnight. The mixture is then cooled to room temperature and a solution of 1,3-propane- diamine (0.53 g, 0.0072 mole) in 25 ml of dry tetrahydro- furan added dropwise. After this addition, the mixture is stirred at room temperature for 1 hours and then heated to reflux overnight. The mixture is cooled to room temperature and poured into 300 ml of water with stirring. The mixture is extracted with three 200-ml portions of methylene chloride. The methylene chloride

extracts are combined and washed with three 400-ml por¬ tions of a 10 percent hydrochloric acid solution. Next, the methylene chloride extract is washed with one 500-ml portion of water followed by two washings with 400-ml portions of saturated sodium bicarbonate. Finally, the methylene chloride extract is washed with two 500-ml por¬ tions of water and dried over anhydrous magnesium sulfate. The magnesium sulfate is filtered off and the filtrate evaporated to yield 2.5 g of crude product. This is recrystallized from ethanol to yield 1.5 g (0.0045 mole) of pure product. The melting point of the product is 172°C-178°C.

(b) n = 5

The same procedure and workup is used as in the preceding example. The quantities of reactants and product are: benzocyclobutene 4-carboxylic acid (2.22 g, 0.015 mole); 1,1-carbonyldiimidazole (2.38 g, 0.0147 mole); 1,5-pentanediamine (0.72 g, 0.0071 mole); and product weight (1.8 g, 0.0049 mole). The melting point is 181°C-185°C.

(c) n = 6

The same procedure and workup is used as in the procedure where n = 3. The quantities of reactants and product are: benzocyclobutene 4-carboxylic acid (2.22 g, 0.015 mole); 1,1-carbonyldiimidazole (2.43 g, 0.015 mole); 1,6-hexanediamine (0.79 g, 0.0068 mole); and product weight (0.65 g, 0.0017 mole). The melting point is 185°C-194°C.

( d) n = 7

The same procedure and workup is used as in the procedure where n = 3. The quantities of reactants and product are: benzocyclobutene 4-carboxylic acid (2.22 g, 0.015 mole); 1,1-carbonyldiimidazole (2.48 g, 0.015 mole); 1,7-heptanediamine (0.99 g, 0.0076 mole); and product weight (0.6 g, 0.0015 mole). The melting point is 141°C-145°C.

In 10 ml of N-methyl-2-pyrrolidinone is dis- solved 2.0 g of monomer (d) n = 7. To this solution is added 0.5 g of lithium chloride. The mixture is stirred and refluxed under nitrogen for 5 hours. Thereafter the solution is cooled to room temperature and into the mixture is poured 250 ml of water. The polymer pre- cipitates upon addition of the water. The polymer is filtered off and vaccum dried at 150°C.

(e) n = 8

The same procedure and workup is used as for the procedure where n = 3. The quantities of reactants and product are: benzocyclobutene 4-carboxylic acid (1.48 g, 0.01 mole); 1,1-carbonyldiimidazole (1.62 g, 0.01 mole); 1,8-octanediamine (0.65 g, 0.0045 mole); and product weight (0.5 g, 0.0012 mole). The melting point is 172°C-176°C.

When the monomers prepared above are tested according to the procedures of Example 2, the following results are obtained.

Monomer Melting

Point Polymerization Temperature (°C) n CO DSC Onset DSC Peak

3 175 240 271

5 181 241 271

6 187 240 271

7 ^• 142 240 272

8 174 239 272

Example 4 - Formation of

A 2000-ml three-neck, round-bottom flask is equipped with magnetic stirrer, 125-ml addition funnel, reflux condenser with nitrogen blanket, and stopper. To this system is added 25.62 g of 4,4'-isopropylidene diphenol (bisphenol A, m.w. 228.3 g, 0.1122 mole), 24.0 of (CH ₃ CH ₂ ) ₃ N (0.238 mole, m.w. 101 freshly distilled over Na metal), and 600 ml of CH ₂ C1 ₂ (Burdick and Jack¬ son brand). This flask is now cooled with an ice water bath to 10°C, with stirring, and 38.78 g of benzocyclo- butene 4-acid chloride (m.w. 166.5 g, 0-.233 mole) in 75 ml of CH ₂ C1 ₂ is entered into the addition funnel. This solution is added dropwise to the stirring bisphe¬ nol A solution. When all of the acid chloride solution has been added, the addition funnel is washed with 2 x 100 ml of CH 2-C12. T»he reaction mixture is then allowed

to stir overnight. The mixture is then entered into a separatory funnel and washed with 500 ml of water, 500 ml of HC1 (5 percent), 500 ml of water, 500 ml of NaHC0 ₃ (saturated), 500 ml of water, and dried over MgSO.. The mixture is then checked by HPLC to determine the rela¬ tive purity of the monomer produced. The methylene chlo¬ ride is removed via rotary evaporation and the resultant off-white solid is recrystallized from 600 ml of' acetone. The first crop of white crystals is removed from solution via filtration and the solution remaining is concentrated to 250 ml and again recrystallized. The second crop of crystals is also isolated via filtration and the remain¬ ing solvent is removed to leave a light brown residue. Final weights and purity (by HPLC) are as follows: first crop, 42.10 g, 99.8 percent; second crop, 6.07 g, 99.3 percent; residue, 6.6 g. Yield is 88 percent of theo¬ retical.

The monomer is devolatilized at 100°C and 0.5 mm Hg vacuum (67 Pa) for two hours, cooled and the vacuum is backlet -with nitrogen. The devolatil¬ ized monomer (0.5 g) is then transferred to a test tube with a ground glass joint, and equipped with a gas inlet tube topped with T and mineral oil bubbler for nitrogen blanket. The test tube is then placed in a Woods metal bath at 100°C and slowly taken up to 250°C. The temperature of the Woods metal bath is held at between 245°C and 250°C for 90 minutes. At the end of this time the test tube is removed from the bath and allowed to cool, still under nitrogen blanket. When cool to the touch, the gas inlet tube is removed and the polymer that remains in the tube is examined. The piece is light yellow in color, contains some

voids, and cannot be fractured with a spatula to remove it from the tube.

Example 5 - Preparation of monomers

(a) q = 3

A 25-ral flask equipped with a reflux con¬ denser, nitrogen inlet, and magnetic stirring bar is charged with m-dibromobenzene (1.0 g, 4.2 x 10 -3 m), m-divmylbenzene (2.75 g, 2.1 x 10 -2 ), tπ-n-butyl-

-3 amine (8.4 x 10 m), tri-o-tolylphosphme (64 mg, 2.1 x 10 -4 m), palladium (II) acetate (20 mg, 8.4 x

10 ^" m), and. acetonitrile (10 ml). The mixture is stirred under nitrogen and heated to reflux for 2 hours. The grey slurry is cooled to room temperature and stirred into 60 ml of 10 percent hydrogen chloride. The resulting precipitate is collected by filtration, washed with water, and air dried. This product is dis- solved in ethylacetate, filtered, and the solvent evapo¬ rated to yield a yellow residue. Recrystallization of the residue from heptane gives 0.60 g (42 percent yield) of a compound of the formula

hereinafter referred to as de erminal olefin, with a melting point of 105°C.

A 25-ml flask equipped with a reflux conden¬ ser, nitrogen inlet and magnetic stirring bar is charged with 4-bromobenzocyclobutene (1.5 g, 8 x 10 -3 moles), the determmal olefm from part A (1.34 g, 4 x 10 -3 moles),

-3 tπ-n-butylamme (1.8 g, 9.7 x 10 moles), tπ-o-tolyl- phosphine (62 mg, 4.0 x 10 -4 moles), palladium II acetate (18 mg, 8.0 x 10 -5 moles) and acetonitrile (5 ml). The reaction mixture is heated to reflux under nitrogen for

4 hours. The mixture is cooled to room temperature and stirred into 60 ml of 10 percent hydrochloric acid. The precipitate is collected by filtration, washed with water and air dried. The dried precipitate is then dis¬ solved in 150 ml of boiling toluene, filtered hot and cooled to yield 310 ml of the product q = 3. The mono- mer has a melting point of 180°C-215°C.

(b) g = 1

A 25-ml flask equipped with a reflux con¬ denser, nitrogen inlet, and magnetic stirring bar is charged with 4-bromobenzocyclobutene (1.50 g, 8.0 x 10 -3 m) , m-divm . ylbenzene (4.0 x 10 -3 m) , tπ-n-butyl-

_ ₃ am e ( 1.8 g, 9.7 x 10 m) , tπ-o-tolylphosphme ( 62 mg, 4.0 x 10 -4 m), palladium (II) acetate (18 mg, 8.0 x 10 -5 m), and acetoni.trile (5 ml). The reacti.on mi.x¬ ture is heated to reflux under nitrogen with stirring for 4 hours. The solidified mixture is cooled to room temperature and stirred into 60 ml of 10 percent hydro¬ gen chloride. The resulting precipitate is collected by filtration, washed with water, and air dried.

The precipitate is dissolved in 75 ml of boiling ethylacetate, filtered hot, and cooled to yield 800 mg (60 percent) of the desired monomer with a melt¬ ing point of 150°C-152°C.

The following monomers are tested according to the procedures of Example 2. The results are com¬ piled in Table III.

Monomer A

Monomer B

Monomer C

Monomer D

CN

-65-

Moftomer E

Monomer F

Monomer G

TABLE III

Melting Polymerization Temperature (°C)

Monomer Point DSC Onset DSC Peak

Series A p=5 161-163 200 270 ¹ p=7 163-165 200 270 ¹ . p=8 174-177 200 270 ¹

B 137 200 260 ²

C 83 200 260 ²

D* none complex

E* none complex

F 67-78 200 261 ²

G 224 200 260 ²

*No melting point observed. A complex differen- tial scanning colorimetry exotherm was observed.

¹ Heating rate 20°C/minute. ² Heating rate 10°C/minute.

Example 6 - Preparation of vinyl bridged benzocyclobutene

A 25-ml flask equipped with a reflux con¬ denser, nitrogen inlet, and magnetic stirring bar is charged with 4-bromobenzocyclobutene (2.39 g,

1.31 x 10 -2 m) , 4-vmylbenzocyclobutne (1.70 g, 1.31 x 10 -2 m), tπ-o-tolyphosphme (100 mg, 3.3 x 10 -4 m), and acetonitrile (10 ml). The reaction mixture is heated to reflux under nitrogen with stirring for 4 hours. The solution is thereafter cooled to room temperature and stirred into 60 ml of a 10 percent hydrochloride acid solution. The resulting precipitate is collected by filtration,

washed with water, and air dried. This yellow crystalline material is recrystallized from heptane/ethylacetate to yield 2.0 g (66 percent) of a vinyl bridged bis(benzocyclobutene) with a melting point of 132°C-133°C.

Example 7 - Preparation of an ethane bridged (bis-benzocyclobutene)

A Parr hydrogenator bottle is charged with a vinyl bridged bis(benzocyclobutene) (660 mg, 2.8 x 10 -3 m), absolute ethanol (100 ml), 5 percent palladium-

-on-carbon (60 mg), and 50 psi (344 kPa) of hydrogen.

After 6 hours, the catalyst is removed by filtration, and the solvent is evaporated. The white residue is recrystallized from heptane to yield 560 mg (85 per- cent) of ethane bridged bis(benzocyclobutene) with a melting point of 86°C to 87°C.