CATALYSED ALTERNATING COPOLYMERISATION AND PRODUCT This invention relates to copolymerization processes; more particularly, this invention relates to processes for the prepara¬ tion of copolymers comprising sequences of alternating monomer residues, and to copolymers so prepared. Mixtures of monomers which are capable of copolymerizing when treated with a conventional polymerization catalyst normally form copolymers in which the residues of the monomers are distributed in a more or less random manner along the polymer chain. It has recently been shown that certain monomer mixtures react in the presence of a Lewis acid to give alternating copolymers i.e. copolymers in which the monomer residues alternate regularly along the polymer chain; and also that this alternating copolymerization proceeds more rapidly if a peroxide is added. Large proportions of Lewis acid are however required; accordingly the process is expensive to operate and may also involve a troublesome separation of-Lewis acid from the copolymer formed.

This invention seeks to provide an improved process for the preparation of copolymers comprising sequences of alternating monomer residues such that they may readily be obtained using comparatively small proportions of Lewis acid thus providing an easier and more economical process.

According to the invention there is provided a process for the preparation of copolymer comprising sequences of alternating monomer residues, which process comprises reacting at least one donor monomer with at least one acceptor monomer in the presence of:

(i) a transition metal complex comprising at least one tf-acid ligand; (ii) an organic compound, which may be a polymer, compris- ing at least one carbon-halogen bond, an acetylenic bond or an ethylenic bond conjugated with one or more electron attracting (-R) groups; and (iii) a Lewis acid.

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Donor monomers include those mono- or poly-unsaturated com¬ pounds having no (-R) substituent conjugated with the or each unsaturated bond and having at most two, preferably at most one, (-1) substituent bonded to any given unsaturated carbon-carbon bond. Classes of such compounds include unsubstituted or substituted hydrocarbons, (thio)ethers, (thio)esters or (thio)amides. Suitable unsubstituted or substituted hydrocarbons include:

(iv) a terminal olefinically unsaturated compound of the general formula:

wherein:

R and R , which may be the same or different, each repre- sents a hydrogen or halogen atom or an unsubstituted or halo- substituted C. to C_ _n hydrocarbyl group;

^' (v) an internal olefinically unsaturated compound of the general formula:

wherein:

R and R, , which may be the same or different, each repre¬ sents an unsubstituted or halo-substituted C to C hydrocarbyl group; R represents a hydrogen atom or an unsubstituted or halo- substituted C to C hydrocarbyl group; and

R _^ represents an unsubstituted or halo-substituted C to C 6 1 20 hydrocarbylene group;

(vi) a C, to C polyene containing at least one olefinically unsaturated group to which are bonded at least two hydrogen atoms; or

(vii) an acetylenic compound of the general formula:

R C ≡ CR ₀ 7 8 wherein:

R represents a hydrogen atom or a C to C hydrocarbyl group; and

R ₀ represents a hydrogen atom or a polymerisable unsaturated o group containing C to C hydrocarbyl group- Examples of such donor monomers include ethylene, propylene, butene-1, butene-2, isobutylene, pentene-1, pentene-2, 2-methyl- butene-1. 3-methylbutene-l, 2-methylbutene-2, hexene-1, hexene-2, hexene-3 , 2-methylpentene-l, 4-methylpentene-l, 2-methylpentene-2, 3-methylpentene-2, heptene-1, heptene-2, heptene-3ι 4-methyl- hexene-1, 3 ^-m ethylhexene-3 ₁ octene-1, decene-1, decene-2, dodecene-1, octadecene-1, octadecene-2; styrene, α-methylstyrene, β-methylstyrene, m-methylstyrne, p-methylstyrene, -ethylstyrene, allylbenzene, isopropenylbenzene, 4-phenylbutene-l, 4-phenyl- butene-2, 5-phenylρentene-2, α-butylstyrene, dihydronaphthalene, vinylnaphthalene, trans-stilbene; 1-methylenecyclobutane, vinylcyclobutane, cyclopentene, vinylcyclopentane, cyclohexene, vinylcyclohexane, norbornene-2; butadiene, isoprene, 1,3-penta- diene, 1, -pentadiene, 1,3-hexadiene, 1,4-hexadiene; acetylene, methylacetylene, ethylacetylene, hexyne-1, phenylacetylene, cyclohexylacetylene, vinylacetylene, divinylacetylene, hexen-1- yne-4, butenylmethylacetylene, allylethylacetylene, allylcyclo- hexylacetylene; vinyl chloride, vinyl bromide, allyl chloride, allyl bromide, 2-chloropropene-l, 2-(chloro ethyl)propene-l, 2-chlorobutene-l, 2-chlorallyl chloride, 3-chlorobutene-l, 4-chlorobutene-l, methallyl chloride, 4,4,4-trichlorobutene,

3-bromopentene-l, 2,4-dichloropentene-l, 1,5-dichloropentene-2, l-chloromethylbutene-2, l-chloro-3-methylbutene-2, 2-bromododecene-l, p-chlorostyrene, o-chlorostyrene, m-chlorostyrene, m-bromostyrene, p-fluorostyrene, p-(chloromethyl)styrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, 2,4-difluorostyrene, 2,6-difluorostyrene,

3-(trifluoromethyl)styrene, α-chloro:-p-methylstyrene, α-bromostyrene

_O -chlorostyrene, p-bromo- α-chlorostyrene,α-(bromomethyl) styrene, α-(chloromethyl)styrene, p-chloro-α -methylstyrene, 2,3-dichloro-α-methylstyrene, ct-ethyl-m-(trichloromethyl)- styrene, p-chloroallylbenzene, 1-chloro-l-benzylethylene, 1, l-bis(p-chlorophenyl)-ethylene, 4-chloro-l-vinylnaphthalene, 1-chloro-l-cyclohexylethylene.

Suitable (thio)ethers, (thio)esters or (thio)amides have the general formula:

wherein: _ represents an unsubstituted or substituted C to C

9 1 20 hydrocarbyl group;

R represents a polymerisable unsaturated group containing C to C hydrocarbyl group;

R represents a C to C hydrocarbylene group; R represents a hydrogen atom or a C to C hydrocarbyl group;

Z represents an oxygen or sulphur atom; Y represents an oxygen or sulphur atom or an -NR group; and m represents zero or 1. Examples of such donor monomers include vinyl acetate, vinyl propionate, vinyl pelargonate, vinyl-2-ethyl- hexanecarboxylate, vinyl stearate, ethyl inyl oxalate, vinyl chloroacetate, vinyl thiolacetate, vinyl benzoate, vinyl cyclohexanecarboxylate, vinyl-norbornane-2-carboxylate, allyl acetate, allyl laurate, allyl cyclobutanecarboxylate,

2-chloroallyl acetate, isopropenyl acetate, ^α -methallyl acetate, 1-propenyl acetate, 1 ^' Bobutenyl butyrate, N-vinylacetamide, N-allyl-N-methyl-propionic acide amide, N-vinylbenzoic acid amide, N-vinylthioacetamide, N- vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam and vinyl ether.

Mixtures of two or more donor monomers may be used in which case the different donor monomer residues will be distributed in a random manner as the alternating donor monomer residues in the copolymer chain.

Acceptor monomers include those unsaturated compounds which form a complex with a Lewis acid. Preferred such compounds include olefinically unsaturated compounds having a (-R) substituent conjugated with an unsaturated bond.

Suitable olefinically unsaturated compounds have the general formula:

R ¹ CH=CR ^I]C Q wherein:

R and R , which may be the same or different, each represents a hydrogen or halogen atom or an unsubstituted or halo-substituted C to C hydrocarbyl group, with the

¹ ~ I II proviso that at least one of R and R represents a hydrogen atom; and

Q represents a nitrile group or a group of the formula:

-C-Y' II Z' wherein:

Y' represents a group of the formula Z"R' , Z"Me / , n

NR"R'" or R"", Z' and Z", which may be the same or different, each represents an oxygen or sulphur atom,

R ¹ , R" , R" ' or R"", which may be the same or different, each represents a hydrogen atom or a C to C hydrocarbyl group, with the proviso that R"" may also represent a halogen atom and R" and R'" may, together with the nitrogen atom to which they are bonded, represent an N-linked heterocyclic group, and

Me represents a salifying metal of valency n.

Examples of such acceptor monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, n-amyl acrylate, n-octylacrylate, octadecyl acrylate, allyl acrylate,

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(

o-toluyl. acrylate, benzyl acrylate, cyclohexyl acrylate, 2-chlorethyl acrylate, 3-chloroallyl acrylate, methyl α-chloroacrylate, methyl a-bromo acrylate, methylα-(p- chlorophenyl) acrylate, ethyl α -chloroacrylate, methyl thiolacrylate, ethyl thiolacrylate, methyl thionacrylate, methyl di-thioacrylate, acrylonitrile, acrylamide, thioacrylamide, N-methylacrylamide, N-n-butylacrylamide, _ N_-n-octylacrylamide, N-2-ethylhexyl acrylamide, N-stearyl acrylamide, N-cyclohexyl acrylamide, N-toluyl acrylamide, N-methyl thioacrylamide, N,N-dimethyl acrylamide, N-methyl- N-ethyl acrylamide, N_, N-di-n-butylacrylamide, acrylyl morpholine, acrylyl pyrrolidine, N,N-dimethylthioacrylamide, acryloyl chloride, acryloyl bromide, thioacryloyl chloride, acrylic acid ^" , thiolacrylic acid, thionacrylic acid, dithioacrylic acid, sodium acrylate, potassium acrylate, zinc acrylate, aluminium acrylate, ammonium acrylate, acrolein, methylvinylketone, ethylvinylketone, phenylvinylketone, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octadecyl methacrylate, benzyl methacrylate, phenyl methacrylate, toluyl methacrylate, cyclohexyl methacrylate, 2-chloroethyl methacrylate, methyl thiolmethacrylate, ethyl thiolmethacrylate, methyl CL-ethylacrylate, ethyl ^β -butylacrylate, methyl O-cyclohexylacrylate, methyl t -phenylacrylate, methacrylamide, N-ethyl methacrylamide, N-cyclohexyl methacrylamide, N,N-dimethyl methacrylamide, methacrylyl piperidine, α-ethylacrylamide, α-chloroacrylamide, α-chloromethyl acrylamide, methacryloyl chloride, α-chloroacryloyl chloride, α-ethylmethacryloyl chloride, methacrylic acid, thiolmethacrylic acid, sodium methacrylate, zinc methacrylate, aluminium methacrylate, ammonium α-fluoroacrylate, methacrolein, methylisopropenylketone, 1-chloro-butenyl-ethylketone, methacrylonitrile, o-ethylacrylonitrile, d-cyclohexylacrylonitrile, Of-chloroacrylonitrile, α-chloromethylacrylonitrile, methyl

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- 1 - crotonate, ethyl crontonate, n-butyl crotonate, phenyl crotonate, crotonamide, crotonoyl chloride, crotonitrile, methyl cinnamate, butyl cinnamate, chloromethyl cinnamate, cinnamic nitrile, methyl/? - ethylacrylate and methyl /3-chloromethylacrylate.

If there are two conjugated electron withdrawing groups they should both be on the same carbon atom.

Mixtures of two or more acceptor monomers may be used in which case the different acceptor monomers will be distributed in a random manner as alternating acceptor monomer residues along the copolymer chain.

It is preferred to use equivalent proportions of donor and acceptor monomers. Any stoichiometric excess of either monomer will usually remain unchanged although in some cases slight formation of homopolymer may take place.

The transmition metal complex (i) may be any such complex stabilised in a low oxidation state, typically

0 or +1, by a π-acid ligand. Generally the transition metal will be Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd or Pt, notably Cr, Mo, ¥, Mn, Re, Fe, Co, Ni and Pt, especially Mn, Re and Ni. Suitable ττ-acid ligands are organometallic such ligands and mono- or polydentate alkyl and aryl phosphines and phosphites, and mono- and polydentate pyridines. Examples of organometallic such ligands include carbonyl, alkyl and aryl isocyanides, and organic compounds, notably hydrocarbons, comprising acetylenic, olefinicand aromatic unsaturation.

In the transition metal complexes (i) one or more such 7T-acid ligands may be present. Other ligands may also be present.

Examples of such transition metal complexes include

Cr(CO),; (CO).Cr (PMe ) Cr(CO), ; (CO) Cr PMe„ PMe„ Cr(CO) ; 0 4 2 2 - 5 2 2 5

Mo(CO),; Mo(CO) Py; (CO) Mo(PMe ) Mo(CO). ; (CO) MoPMe PMe Mo (CO) : (Cθ) MoPEt PEt Mo(Cθ)__ ; W(C0),; Cr(CNAr),; ώ 5 5 2 5 O O

chlorine or bromine atom may be removed during the reaction.

In general bromo compounds are more active than chloro compounds and activity is greatest in those compounds having more than one chlorine or bromine atom on one carbon atom or in which a further electron withdrawing substituent is adjacent to the halogenated carbon atom. Examples of such compounds are compounds containing CCI or CBr groups, such as CC1 , CHC1 ,

3 3 4 3

CHBr , trichloracetic acid and esters thereof, for example ethyl chloroacetate; compounds containing CBr and CBr groups, such as a-(di)-bromoketones and benzyl bromide. Compounds containing NCI or NBr groups, for example N-chloro. or

N-bromo amides or amides, such as N-bromosuccinimide and N-chloro-substituted nylon may also be used.

Saturated fluorine compounds containing no chlorine or bromine are inactive; iodine compounds have a propensity to liberate molecular iodine which acts as a retarder. Chlorine and bromine-containing donor or acceptor monomers may also serve as component (ii).

However, fluorine compounds in which at least one fluorine atom is bonded to an unsaturated carbon atom such as mono- or poly-fluoro olefins, are effective photoinitiators, although fluorine is not removed during reaction; rather the fragment of (i) arising from the photolysis adds to the fluorine compound to give a free radical; for example Mn (CO)

10 with CF =CF may give the reactive species (CO) MnCF CF .

Other photoinitiating compounds (ii) in which halogen is not removed are organic compounds comprising an acetylenic bond or an ethylenic bond conjugated with one or more (-R) groups. Examples include acetylene and acetylene mono and dicarboxylic acids and their esters, such as acetylenedicarboxylic acid and dimethyl- acetylenedicarboxylate; olefinic mono and dicarboxylic acids, their esters and anhydrides, such as diethylfumarate, diethyl maleate and maleic anhydride.

The Lewis acid (iii) suitably has the general empirical formula: R ^V X„ n 3-n wherein:

M represents an aluminium or boron atom; v R represents a hydrocarbyl group;

X represents a fluorine, chlorine or bromine atom; and n.represents zero or any number, including fractional numbers, up to and including three; or comprises a mixture of a Group IIB, IIIB or IVB organometallic compound with a Group IIIB orIVB halide.

Examples include methylaluminium dichloride, ethylaluminium dichloride, isobutylaluminium dichloride, hexylaluminium dichloride, dodecylaluminium dichloride, phenylaluminium dichloride, cyclohexyl- aluminium dichloride, methylaluminium dibromide, allylaluminium dichloride, ethylaluminium sesquichloride, ethylaluminium sesqui- bromide, methylaluminium sesquichloride, diethylaluminium chloride, ethylphenylaluminium chloride, dicyclohexylaluminium chloride, methylboron dichloride, ethylboron dichloride, butylboron, dichloride, hexylboron dichloride, dodecylboron dichloride, phenylboron dichloride, benzylboron dichloride, cyclohexylboron dichloride, diethylboron bromide, dipropylboron chloride, dibutyl- boron chloride, dihexylboron chloride, ethylvinylboron chloride, dicyclopentadenylboron chloride, trimethylaluminium, triethyl- aluminium, tripropylaluminium, tributylaluminium, trihexylaluminium, tridecylaluminium, triphenylaluminium, tricyclohexylaluminium,

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tribenzylaluminium, trimethylboron, triethylboron, tributylboron, trihexylboron, diethylphenylboron, diethyl p-toluylboron, tricyclo- hexylboron, aluminium trichloride, aluminium tribromide, boron trichloride, boron trifluoride, boron tribromide, and one or more of diethylzinc, ethylziήc chloride, diethylcadmium, diethylmercury, diphenylmercury, triethylboron, tributylboron, tricyclohexylboron, ethylboron bromide, triethylaluminium, tributylaluminium, trihexyl¬ aluminium, tricyclohexylaluminium, vinyldiethylaluminium, diethyl¬ aluminium chloride, ethylaluminium. sesquichloride, ethylaluminium dichloride, trimethylgallium, triethylgallium, triethylindium, tetraethylgermanium, tetramethyltin, tetraethyltiή, tetraisobutyl- tin, dimethyldiethyltin, tetraphenyltiri, tetrabenzyltin, diethyl- diphenyltin, triethyltin chloride, diethyltin dichloride, ethyltin trichloride, tetramethyllead, tetraethyllead, di ethyldiethyllead, and triethyllead chloride, mixed with one or more of boron tri¬ chloride, boron trifluoride, boron triboromide, boron triiodide, ethylboron. dichloride, diethylboron chloride, aluminium trichloride, aluminium tribromide, aluminium triiodine, partially fluorinated aluminium chloride, ethylaluminium dichloride, methylaluminium dibromide, ethylaluminium sesquichloride, diethylaluminium chloride, gallium trichloride, gallium dichloride, germanium tetrachloride, tin tetrachloride, tin tetrabromide, ethyltin trichloride, methyl- tin trichloride, phenyltin trichloride, dimethyltin dibromide, diethyltin dichloride, diisobutyltin dichloride, triethyltin chloride, lead tetrachloride, and diethyllead dichloride.

The process is suitably effected in absence of oxygen, con¬ veniently in vacuum or under a blanket of an inert gas, for example nitrogen.

It is preferred to operate the process in an inert solvent, for example a hydrocarbon such as toluene. The copolymer may be isolated by any conventional method, for example by precipitation by a non-solvent such as methanol.

In order to obtain an acceptable rate of copolymerization it is desirable in some cases to use a slightly elevated temperature, o o for example between 60 and 100 . Organometallic derivatives of molybdenum are especially suitable for use within this temperature range, while those of nickel may have sufficient activity for use down to ambient temperatures.

Alternatively the rate of polymerization may be increased by irradiating the process mixture with ultra-violet light.

Irradiation by light of λ = 436 nm is suitable for a copolymer- ization catalysed by an organometallic derivative of manganese, while light of λ = 36 nm is more suitable for use with a rhenium derivative. With photoinitiation, temperatures below 0 C are o also suitable.

In favourable cases an initial copolymerization rate of 1.5% per minute may be obtained.

Suitable concentrations of either monomer in the process mixture are up to 2 mol per litre.

Suitable amounts of catalyst will depend on the activity of the catalyst chosen but amounts down to 0.002 mol % of monomer may be used in favourable cases.

Suitable amounts of the compound (ii) will depend on the activity of the compound and also on the nature of the transition metal complex (i). Carbon tetrachloride may be used in amounts down to 0.5 mol % of monomer, but with carbon tetrabromide this may be reduced to 0.05 mol %.

Amounts of Lewis acid (iii) down to 5 mol % of monomer may be used.

As noted earlier component (ii) may itself comprise a polymer which comprises at least one carbon-halogen bond. Such polymers can be produced by free radical polymerization, which may proceed in accordance with the invention or conventionally, in the presence of a monomeric organic compound comprising at least one carbon- halogen bond. A halogen-containing fragment of the organic

compound will be present as a terminal group in a homopolymer or a random or alternating copolymer. Two examples will make this clear:

(a) methyl methacrylate free radically homo polymerised by heat in the presence of peroxide and CBr, will give:

COOCH„ _Br - (-CH ₂ - C -) _n CBr ₃ CH ₃

(b) styrene and methylacrylate free radically polymerised in accordance with this invention in the presence of CC1, and

Ni(CO) \ P(OPh) A _n will give:

COOCH I 3,

Cl CH - CH - CH CH -

(- *X CC1

3 Ph

Such polymers can also be produced, with a plurality of pen- dant halogen-containing groups, by homo- or random or alternating copolymerising olefinically unsaturated monomers containing them; for example vinyl trichloracetate can be homo- polymerised to:

(en -CΆ - 2} n

o=

(wherein Ph represents a phenyl group and n represents a number at least 2). In accordance with a further aspect of this invention, there¬ fore, there is provided a block or graft alternating copolymer prepared by the process of the invention and utilising, as com¬ ponent ^" (ii) a polymer as hereinabove defined. Such polymers may comprise one or a plurality of alternating blocks, for example: AAAAACBr BDBDBD ...

...AAABABBAABCBr DEDEDE... ABABABCBr DEDEDE...

o;,-:?ι

or may comprise grafts with alternating branches, for example A - A B A B

1 0 0 0

1

0=C 0 j =c 0=C ccι ₂ ccι ₂ ccι ₂

D D D D

E E E

D D D

E E E

These branches may cross-link the backbone chains.

The copolymers obtained are similar in arrangement of the monomer residues, in tacticities and in general properties, to those obtained by the conventional use of peroxide catalysts in presence of Lewis acids.

The copolymers are of utility in a number of ways. Control of the regularity of the copolymerization may provide copolymers of desired physical or chemical properties- in greater consistency. Furthermore copolymers in which reactive groups are distributed regularly rather than at random may facilitate the manufacture of copolymers containing groups which may confer a variety of useful properties on the copolymer.

The invention is illustrated but not limited by the following Examples. Example 1

4.6 ml toluene, 1.04 g styrene, 2.58 g methylacrylate, 0.15 g carbon tetrachloride, 0.2 g Al Et Cl and 0.0011 g Mn (CO) were mixed in a glass tube which was then cooled in liquid nitrogen. The mixture was degassed by repeated freezing, evacuating and melting whereafter it was finally cooled in liquid nitrogen, and the tube evacuated and sealed. The tube was next allowed to warm to o to room temperature and then irradiated at 25 C by light of λ. = 436 nm (from a 250 watt high-pressure mercury arc) for 10 minutes. The product mixture was poured into excess methanol to give 0.26 g of alternating copolymer collected by filtration.

The structure was confirmed by nmr examination and elemental analysis.

Example 2 The procedure in Example 1 was repeated with 4.1 ml toluene, 3.12 g styrene, 0.86 g methylacrylate, 0.15 g carbon tetrachloride, 0.2 g Al Et Cl and 0.0011 g Mn (CO) . The same product was obtained with a yield of 0.37 g«

Example 3 The procedure in Example 1 was repeated with 100 ml toluene, - 4.2 g of styrene, 3.4 g of methylacrylate, 1.5 g of carbon tetra¬ chloride, 1.23 g of Al ₀ Et Cl and 0.011 g of Mn (CO)..-.. The

2 _J o -* ~S* degassed mixture was irradiated at 25 C by light of = 436 nm for

0.5 hours. 3-0 g of alternating copolymer was collected by fil¬ tration. The structure was confirmed by elemental analysis and nmr examination.

Comparative experiments in which Mn (CO) and/or CC1, were omitted gave 0.2 g of copolymer.

Example 4 100 ml of toluene, 4.2 g of styrene, 3. k g of methyl acrylate,' 1.54 g of carbon tetrachloride, 1.84 g of Al Et Cl and O.OO38 g of Ni(C0) _o P(0Ph) .were mixed, and degassed as described in 2 ^" j 2 o Example 1. The tube was sealed off and allowed to warm up to 25 C. o The reaction mixture was held at 25 C for 0.5 hour without irra¬ diation and then poured into excess methanol to give 3«0 g of alternating copolymer.

Example 5 The procedure in Example 4 was repeated with 100 ml toluene,

4.2 g of styrene, 3.4 g of methylacrylate, 0.5 g of Al Et Cl and _ 2 3 3

0.0038 g of Ni(C0) /P(0Ph) / . The degassed mixture was held at o ^~ -— 3 2

25 C for 0.5 hour, without irradiation and then poured into excess methanol to give 0.3 g of alternating copolymer. When the nickel derivative was omitted no copolymer was pre¬ cipitated.

Example 6 The procedure in Example 1 was repeated with 5.3 ~- toluene, 1.04 g styrene, 1.59 g acrylonitrile, 0.15 g carbon tetrachloride,

/ - ~'-bA -MPI

0.2 g Al Et Cl and 0,0011 g Mn (CO) . The yield of alternating 3 copolymer was 0.20 g.

Example 7 The procedure in Example 1 was repeated with 4.3 ml toluene, 3-12 g styrene, 0.53 acrylonitrile, 0.15 g carbon tetrachloride, 0.2 g Al Et Cl and 0.0011 g Mn (CO) . The yield of alternating m* 3 _* r ^- copolymer was 0.28 g.

Example 8 Repetition of the procedure of Example 1 using 100 ml toluene, 3-4 g of methylacrylate, 2.2 g of butadiene, 1.54 g of carbon tetrachloride, 2.5 g of Al Et Cl and O.O78 g of Mn (CO) afforded after irradiation for 1 hour 1.23 of alternating copolymer. Omission of the manganese led to no copolymer.