Catalyst for Group Transfer Polymerization

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to Group Transfer Polymerization catalyzed by selected silaneε, preferably in the presence of a suitable mercury compound and/or Lewis acid. Background

United States Patents 4,414,372; 4,417,034; 4,508,880; 4,524,196; 4,581,428; 4,588,795 4,598,161; 4,605,716, 4,622,372; 4,656,233 4,659,782; 4,659,783; 4,681,918; 4,695,607 4,711,942; and 4,732,955; and in commonly assigned United States Patent Applications Serial Noε. 912,117 filed September 29, 1986; 934,826 filed November 25, 1986; 004,831 filed January 13, 1987; 007,758 filed January 27, 1987; 015,727 filed February 27, 1987; and 048,958 filed May 19, 1987; referred to hereinafter as "the aforesaid patents and patent applications", disclose processes for polymerizing an acrylic or maleimide monomer to a "living" polymer in the presence of: (i ) an initiator which is a tetracoordinate organosilicon, organotin or organogermanium compound having at least one initiating site; and

(ii) a co-catalyst which is a source of fluoride, bifluoride, cyanide or azide ions or a suitable Lewis acid, Lewis base or selected oxyanion. Such polymerization processes have become known in the art as Group Transfer Polymerization (Webster et al. ,J. Am. Chem.Soc. , 105; 5706 (1983)). Preferred monomers for use in Group Transfer Polymerization are selected from acrylic

and maleimide monomers of the formula CH ₂ >=C(Y)X and

CH==.=«CH

I I 0=-C C«0 , and mixtures thereof,

\ /

N

wherein:

X is -CN, -CH«CHC(0)X ^r or -C(0)X'; Y is -H, -CH ₃ , -CN or -CO _j R, provided, however, when X is -CH*CHC(0)X' , Y is -H or -CH ₃ ; __ X' is -OSKR ¹ ^, -R, -OR or -NR'R"; each R ¹ , independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or -H, provided that at least one R ¹ group is not -H; R is:

(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to

20 carbon atoms;

(b) a polymeric radical containing at least 20 carbon atoms;

(c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof;

(d) a radical of (a), (b) or (c) containing one or more functional εubstituents that are unreactive under polymerizing conditions; or

(e) a radical of (a), (b), (c) or (d) containing one or more reactive subεtituents of the formula

-Z ' (O)C-C(Y ¹ )«CH ₂ wherein Y ¹ is -H or -CH ₃ and Z' iε O or NR' wherein R' is aε defined

below; and each of R' and R" is independently selected from C _x _ ₄ alkyl.

Preferred initiators are selected from tetracoordinate organosilicon, organotin and organogermanium compounds of the formulas (Q') ₃ MZ, (Q'l _j MlZ ¹ ), and [Z ¹ (Q' )_M].0 wherein: each Q' , independently, iε R ¹ , OR ¹ , SR ¹ or NfR ¹ )-?

R ¹ iε as defined above for the monomer; z iε an activating substituent selected from the group consisting of

R ² R ² 0

-CN, -C-CN, -C--CX , R ³ R ³

_OC«™CR ² , -SR', -OP(NR'R") ₂ , -OPfOR ¹ ) _, ,

VCH 2 ⁷ n

-OPlOSKR ¹ ) ₃ ] ₂ and mixtures thereof;

R ^r , R", R and R ¹ are as defined above for the monomer; Z ¹ is -OC-C-R ² ;

X ^Z R

X ² is -OSi(R ¹ ) 3,, - ⁶ , -OR ⁶ or -NR'R";

R IS

(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed

— aliphatic-aromatic radical containing up to 20 carbon atoms;

(b) a polymeric radical containing at least 20 carbon atoms; (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segmentε thereof;

(d) a radical of (a), (b) or (c) containing one or more functional subεtituentε that are .unreactive under polymerizing conditionε; or -(e) a radical of (a), (b), (c) or (d) containing one or more initiating sites; and each of R ^z and R ³ is independently selected from -H and hydrocarbyl, defined as for R ^δ above, subparagraphs (a) to (e);

R' , R" and R ¹ are as defined above for the monomer; Z' iε as defined above for the monomer; m iε 2, 3 or 4; n iε 3, 4 or 5;

R ² and R ³ taken together are

R ² 0 provided Z iε -C-CX or -OC-C(ITι„) (.Rι ) ;

X ²

X ² and either R ² or R ³ taken together are

R ² 0

I it provided Z iε -C-CX ² or -0C=C(R ² ) (R ³ ) ; and i r

R ³ X ²

M is Si, Sn, or Ge, provided, however, when Z is

M is Sn or Ge.

Preferred co-catalystε are εelected from a source of bifluoride ions HF ₂ ^~ , or a source of fluoride, cyanide or azide ions, or a source of oxyanions, said oxyanions being capable of forming a conjugate acid having a pKa (DMSO) of about 5 to about 24, preferably about 6 to about 21, more preferably 8 to 18, or a εuitable Lewis acid, for example, zinc chloride, bromide or iodide, boron trifluoride, an alkylaluminum oxide or an alkylaluminum chloride, or a εelected Lewiε baεe.

Additional details regarding Group Transfer Polymerization can be obtained from the aforeεaid

patents and patent applications, the disclosures of which are hereby incorporated by reference.

Razuvaev et al., Vysokomol.Soedin.(B), 25(2) :122-125 (1983) disclose polymerization of methyl methacrylate and/or styrene initiated by a mixture of silicon tetrachloride and alkyls of mercury, tin or lead, at 20-50°C. Sakurai et al.. Tetrahedron Lett. , ^:2325-2328 (1980) disclose mercuric iodide catalyzed isomerization of (trimethylεilylmethyDchloromethyl ketone to (1-chloromethyl ethenyl)oxytrimethylεilane.

Burlachenko et al., Zhur, Obshchei Khim. ,43(8) :1724-1732 (1973) diεclose isomerization of cis-ketene silyl acetals into the tranε-iεomer catalyzed by triethylsilyl bromide and mercuric bromide. Litvinova et al., abstract of Dokl. Akad. Nauk. SSSR, r7 - ³ _* ^:578 - ⁵⁸⁰ (1967); CA £7: 32720J, disclose the mercuric iodide-catalyzed rearrangement of triethylacetonylεilane to (iεopropenyloxy)- triethylεilane. Baukov et al. , abstract of Dokl. Akad.

Nauk. SSSR, 157.-1) :119-121 (1964); CA 61: 8333f, disclose the mercuric iodide-catalyzed rearrangement of [(1-methoxy-l-ethenyl)oxy]triethylsilane to methyl 2-triethylsilylacetate. ^~~ Satchell et al., Qtr. Rev. Chem Soc,

^5_:171 (1971) diεclose that mercuric halides are very weakly acidic Lewis acidε.

Weber, "Silicon Reagentε for Organic Syntheεiε", New York, 1983, Chapter 3, pp 21-39 describes preparation and reactions of trimethylsilyl iodide, bromide and trifluoro ethaneεulfonate (triflate). Theεe reagents are used as catalyεtε for cleaving chemical bondε in organic compoundε and as silylating agents. They are often used in conjunction with organic

bases such as pyridine. A more extensive survey of reactions catalyzed by trimethylsilyl triflate and trimethylsilyl eεterε of "Nafion" perfluorεulfonic acid reεin iε provided by Noyori et al.. Tetrahedron, 37 (23), 3899 (1981). U. S. 3,478,007 discloses polymerization of unsaturated cyclic hydrocarbons using aluminum chloride and a trialkylsilicon halide aε catalyst; AlCl ₃ and trimethylεilyl chloride are exemplified. Toshima et al., Kogyo Kagaku Zasshi 72(4), 984 (1969) discloses polymerization of styrene catalyzed by trimethylsilyl chloride and mercuric chloride.

The above publications do not suggest the use of trialkylsilyl halides with or without added Lewiε acids or mercuric compounds as catalysts for Group Transfer polymerization.

United States Patent 4,732,955, supra, discloεeε Group Transfer Polymerization of one or more acrylate or acrylamide monomers in the presence of a mercury compound of the formula R ⁷ HgI, wherein R ⁷ is a C _χ _ ₁₀ hydrocarbyl radical, or HgL ₂ , wherein L is I or C10 ₄ . Commonly assigned United States

Patent Application Serial No. concurrently filed herewith under Docket No. CR 8417 discloses the use of these mercury compounds, and also Lewis acid/εilane mixtures, as catalysts in the preparation of 1:1 adducts of silyl ketene acetals and α,β-unεaturated compounds, the adducts being effective GTP initiators. Commonly assigned United States Patent

Application Serial No. 015,727, supra, discloseε Group Tranεfer Polymerization in the preεence of a non-initiating εilylated ester or ether, preferably trimethylεilyl 3-chlorobenzoate, said ester or ether serving as a "livingness" enhancing agent.

The present invention provides an improved Group Transfer Polymerization process wherein the catalyst is a selected non-polymerization-initiating silane or a mixture thereof with a suitable mercury compound and/or Lewis acid. Mercury compounds disclosed herein are also disclosed for another use in the commonly assigned application filed herewith under Docket No. CR-8417, supra.

_ -SUMMARY OF THE INVENTION The present invention resideε in a Group

Tranεfer Polymerization (GTP) proceεs comprising contacting under polymerizing conditionε at leaεt one monomer selected from acrylic and maleimide monomers with (i) a tetracoordinate organosilicon, -tin or -germanium compound having at least one initiating site, and (ii) a catalyst which is a suitable Lewis acid or mercury compound, the procesε further characterized in that the catalyεt conεiεtε eεεentially o± (a) about 10 to 100 mol % of a silane of the formula (_R ¹ ) ₃ Si-Z ² whereins each R ¹ , independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or -H, provided that at least one R ¹ group is not —H; and

Z ² is a weakly basic radical, for example, I, Br, Cl, CF ₃ S0 ₃ , CF ₃ C0 ₂ , C10 ₄ , S0 ₄ or 0; and

(b) 0 to about 90 mol % of at least one of a suitable Lewis acid or mercury compound, provided, however, when ^~ Z ³ is other than I, at least 0.5 mole % of suitable Lewis acid or mercury compound selected from R ⁷ HgI, Hgl ₂ and Hg(Cl0 ₄ ) ₂ is present.

DETAILED DESCRIPTION OF THE INVENTION Suitable Lewis acids for use in the process of the invention include zinc iodide, chloride or bromide, boron trifluoride, an alkylaluminum oxide, an alkylaluminum chloride, cadmium iodide, ferric chloride, and stannous chloride.

Suitable mercury compounds include the common mercuric compounds, preferably those of the formula R ⁷ HgI and HgL ₂ wherein:

R ⁷ is a hydrocarbyl radical having 1 to 10 carbon atoms; and

L is I, Br, Cl, CF ₃ C0 ₂ , C10 ₄ , S0 ₄ , trifluoromethane sulfonate (triflate) or 0. Preferably, L is iodide or bromide, most preferably iodide. The Lewis acid or mercury compound, when present in the catalyst composition of the invention, may be supported on an inert insoluble support, such as carbon.

The procesε of the invention may be carried out with or without a εolvent. Suitable solventε are generally thoεe diεcloεed in the aforesaid patentε and patent applications, non-coordinating liquids such as hydrocarbons or chlorinated hydrocarbons being preferred when mercury compounds are present in the catalyst composition. Preferred acrylic monomers and initiators disclosed in the aforesaid patents and patent applications are also preferred in the process; see especially United States Patentε 4,508,880 and 4,732,955 and Application Serial No. 004,831, supra. Acrylateε and N,N-dialkylacrylamides are moεt preferred monomerε for the proceεε of thiε invention.

Process conditions such as temperature, presεure, concentrationε of starting materialε, monomer to initiator ratio, catalyst to initiator

ratio, and precautions against moisture and other hydroxylated impurities are also as described in the aforesaid patents and patent applications. Supplemental details are provided below.

The amount of catalyst composition used in the process of the invention should be at least about 0.01 mole per mole of starting initiator, preferably about 0.05 to about 10 moles per mole of starting initiator, although amounts as high as about 100 moles per mole of initiator can be tolerated.

Preferred catalyst compositionε are thoεe containing from about 0.5 mole % to about 80 mole % of a mercury compound or Lewis acid as previouεly defined. Catalyεt compositions wherein at least one component is an iodide are most preferred.

It will be understood that some, but not all, of the components of the catalyst compoεition of the invention are themεelves catalyεtε for GTP. Components which catalyze GTP include the aforesaid silane, the Lewis acids recited above except cadmium iodide, ferric chloride and stannouε chloride, and mercury compounds of the formula R ⁷ HgI and HgL ₂ wherein R ⁷ is as defined above and L iε I or C10 ₄ . However, aε can be εeen from the enεuing experiments and examples, the catalyεt compositions which contain both the silane and the mercury compound or the Lewis acid are, surprisingly, more active than the individual components, especially at low temperatures. Example 21 shows that a composition of the invention is an active catalyst for the polymerization of ethyl acrylate by GTP at -78*C, although the catalyεt componentε individually are inoperable. Thiε unexpected catalytic εynergiεm found in the preεent catalyεt mixtureε is eεpecially uεeful when it iε deεired to minimize the amount of

mercury or Lewis acid employed in the polymerization process. The present preferred compositions are also more effective catalysts for the polymerization of (meth)acrylates than are the individual components, especially mercury compounds which, alone, are esεentially inactive for polymerizing these monomers.

In the following examples of the invention, weight and number average molecular weights of the polymer products (M _w , F_ _n ) were measured by gel permeation chromatography (GPC). The polydisperεity of the polymer is defined by D«M _w /F_ _n . Unless otherwise specified, the "living" polymer products were quenched by exposure to moist air or methanol before molecular weights were determined. Parts and percentages are by weight and temperatures are in degrees Celsius unless otherwiεe specified.

In several instances catalyεt activity iε measured by the elapεed time prior to the onεet of exothermic polymerization, shorter induction periods repreεenting higher activity. When catalytic activity is weak, polymer may be formed without detectable temperature rise.

Preferred embodiments of the present invention are represented by Examples 3, 5, 6, 8 and 21.

EXAMPLE 1 To a dry 100-mL round bottom (RB) flask were added 20 mL of toluene, 0.40 mL of [ (l-methoxy-2-methyl-l-propenyl)oxy]trimethylεilane (MTS) (2.0 mrooles) and 40 μh of iodotrimethylεilane (TMSI, 0.28 mole). To the mixture stirred under argon waε added 5 L of ethyl acrylate (46 moleε). No exotherm waε obεerved. After about two h 0.66 mL of 0.003M mercuric iodide solution in benzene (d6)

(0.002 mmole) was added. The temperature rose, indicating polymerization. An aliquot was withdrawn (A). Another 3 mL of ethyl acrylate was added and, after polymerization, an aliquot was withdrawn (B). This procedure was twice repeated, providing aliquots C and D. Poly(ethyl acrylate) waε recovered from each aliquot: GPC: Aliquot fin fin(theory) D

A 2580 2400 1.18

B 4250 3800 1.26

C 5920 5200 1.49

D 8480 6560 1.78

EXAMPLE 2 A. Example 1 was repeated using 0.009 mmole of mercuric iodide and, initially, no TMSI.

Temperature riεe, indicating polymerization, occurred after about 45 min.

B. The experiment of Part A waε repeated except that 2.0 m oles of TMSI was also added.

Exothermic polymerization occurred within 1 minute, indicating more efficient catalysis.

EXAMPLE 3 To a dry 100-mL RB flask were added 20 mL of toluene, 1.0 mL of 0.003M mercuric iodide solution in benzene (0.003 mmole), 2.0 mL-of [ (l-_2-trimethylsiloxyethoxy-2-methyl-l-propenyl)- oxyltrimethylεilane (TTEB) and 44 μ of TMSI (0.31 mmole). To thiε solution was added 10 L of ethyl acrylate (92 mmoles). Exothermic polymerization occurred. After polymerization appeared complete, 0.52 mL of 1,3-dioxolane was added to cap the "living" polymer. A quantitative yield of poly(ethyl acrylate) (PEA) was obtained. GPC: fin

1910; fin (theory) 1700; D 1.16. Hydrolysis of the end-groups in refluxing THF/water/HCl gave the PEA diol with 100 % difunctionality by NMR.

EXAMPLE 4 A. To a dry 100-ml RB flask were added 0.2 g of zinc iodide (0.6 mmole), 20 mL of toluene, 1.97 mL of TTEB (6.2 mmole) and 44 μh of TMSI (0.31 mmole). To this mixture was added 10 L of ethyl acrylate over 11 minutes. The mixture temperature rose rapidly during monomer addition and an ice bath was used to keep the temperature below 31*. The polymer was quenched with 1,3-dioxolane and εtripped to give a quantitative yield of PEA. GPC: fin 1800; fin (theory) 1700; D 1.19. B. The experiment of Part A waε repeated except that no TMSI waε added. Polymerization occurred after an induction period of 17 min. The recovered polymer had a bimodal molecular weight diεtribution, indicating poor molecular weight control. GPC: fin 1120; fin (theory) 1700; D 1.49.

EXAMPLE 5 To a 100-mL RB flask was added 0.05 g of zinc iodide (0.16 mmole), 20 mL of toluene, 0.32 L of TTEB (1.0 mmole) and 15 mL of ethyl acrylate. No polymerization was observed. After 1.25 h, 10 μL of TMSI were added. Exothermic polymerization occurred, requiring external cooling. A quantitative yield of PEA was obtained. GPC: fin 20,200; fin (theory) 19,000; D 1.25.

EXAMPLE 6

To a 100-mL flask containing 0.035 g of zinc bromide (0.16 mmole) , 20 mL of toluene and 0.32 mL of TTEB (1.0 mmole) was added 11 L of ethyl

acrylate. No exotherm was observed. To the mixture was then added 0.26 mL of bro otrimethylsilane. Rapid temperature rise was observed, and a quantitative yield of PEA was obtained. GPC: fin 15,000; fin (theory) 10,300; D 1.24.

EXAMPLE 7 To a 100-mL flask containing 0.1 g of mercuric iodide (0.22 mmole), 20 mL of toluene, 0.64 L of TTEB (2.0 mmoles) and 0.1 L of TMSI (0.7 mmole) was added 10 L of methyl methacrylate (MMA). No exotherm was observed. An additional 0.3 mL of TMSI was added (total 2.8 mmoles). Exothermic polymerization occurred. A 91 % yield of PMMA was obtained. GPC: fin 3310; fin (theory) 4800; D 1.07.

EXAMPLES 8-20

General procedure: To a dry 50-mL bottle with a septum, under argon, were added 3 mL of toluene, 0.4 L of MTS (2.0 mmole), 3 L of ethyl acrylate (0.028 mole) and 2.0 mmole of silane; after 15 min, during which no polymerization was detected, 0.20 mmole of a selected Lewis acid was added, except in Exampleε 8 and 13. The bottle waε hand-shaken and checked periodically for exothermic polymerization. The results are summarized in Table 1. .

EXPERIMENTS 1-5 The procedure of Examples 8-20 was followed except that the silane was omitted, and the Lewis acid was added to the initiator and solvent before monomer addition; these experiments, not of the invention, serve as controls for Exampleε 9, 14, 17, 18 and 20, respectively. The resultε are given in Table 1.

TABLE 1

Example Silane Lewis Acid Exo(min)* fin/D

8 TMSI none (a) 1200/1.17

9 TMSI Znl ₂ <1 849/1.21

10 TMSBr Znl ₂ 3 NA

11 TMSC1 Znl ₂ β NA

12 TMSTf Znl ₂ 1-2 712/1.30

13 TMSTf none (a) 1030/1.30

14 TMSI ZnBr ₂ 4 859/1.58

15 TMSBr ZnBr ₂ 9 NA

16 TMSC1 ZnBr ₂ 10 NA

17 TMSI _SnCl ₄ 20 1320/1.20

18 TMSI Cdl ₂ <1 1370/1.30

^~ 19 TMSBr Cdl ₂ (a) 1090/1.10

20 TMSI FeCl ₃ 40 7980/2.7

Experiment

1 Znl ₂ 15 931/1.35

2 ZnBr ₂ 18 870/1.58

3 SnCl ₄ none no polymer

4 Cdl ₂ none no polymer

5 FeCl ₃ none no polymer

TMS « trimethylsil;yl; Tf - triflate; NA - not available;

* exo(min) is the time (minutes) before an exothermic temperature rise was observed.

(a) - no exotherm was observed; polymer formed slowly overnight;

"none" means no exotherm and no polymerization.

EXAMPLE 21

Separate experiments have shown that acrylateε are not polymerized by GTP at -78° in the preεence of a mercury compound or εilane alone.

To a 100-mL round bottom flaεk were added 20 mL of toluene, 0.40 mL of MTS (2.0 mmoles), 0.66

L of 0.003M mercuric iodide solution in benzene, and 10 mL of ethyl acrylate. The solution was cooled to -78° and 40 μL of TMSI (0.28 mmole) was added. After 69 min, an aliquot was withdrawn for GPC analysis (A). At that time, an additional 40 L of TMSI (0.28 mmole) was added. A slight exotherm was observed; the mixture was allowed to stir for 33 min, then quenched with 1 mL of methanol. After warming to room temperature, a quantitative yield of PEA waε obtained (B). GPC: (A) fin 2510; D 1.21; (B) fin 4190; D 1.08.

The molecular weight of sample A indicates that about 60 % of the monomer had been consumed before the" second addition of TMSI.

EXAMPLE 22

To a dry 50-mL bottle fitted with a septum, under argon, were added 3 mL of toluene, ethyl acrylate (0.019 mole), MTS (2.0 mmoles), and mercuric chloride (0.022 mmole) supported on carbon (12 % HgCl ₂ ) . No polymerization occured. TMSI

(0.14 mmole) was then added, whereupon exothermic temperature rise occurred within seconds, accompanied by rapid viεcoεity riεe, confirming polymerization.