IE46141B1 - Polymerization of compounds having conjugated carbon-carbon double bonds - Google Patents

Abstract

: The present invention is directed to a method for polymerizating a compound containing at least one non-aromatic system of conjugated carbon-carbon double bonds, which romprises contacting the monomer with, as sole catalyst, a compound produced by the reaction in an ethereal solvent of equimolar quantities of sodium and an ethylenic compound having the formula : wherein each of R1, R2, R3 and R4, which can be the same or different, is a hydrogen atom or an alkyl, aryl, aralkyl or alkaryl radical, with the proviso that at least one of R1, R2, R3 and R4 is selected from aryl, aralkyl and alkaryl radicals.

Description

This invention relates to a process for polymerizing a compound containing at least one non-aromatic system of carbon-carbon conjugated double bonds.

It is known from United States Patent Specification No. 3,177,190 5 to use a catalytic system composed by an organic derivative of lithium (for example lithium-isoprenyl) or by an adduct of such a derivative with a cycloaliphatic or aromatic molecule (for example Li-isobutyl, and the dilithiumstilbenedimethylbutadiene adduct) to prepare a polymer having reactive terminal groups.

It is also known (Die Makromolekulare Chemie, 92 (1966), pages 180197) that it is possible to employ such catalytic systems in the polymerization of a few monovinyl monomers, such as acrylonitrile, styrene and methylmethacrylate, in which electron-attracting groups are contained.

We have now found, and this is the basis of the present invention, that it is possible to polymerize compounds which contain at least one system of conjugated carbon-carbon double bonds in the presence of a catalytic system comprising the product of interaction of sodium with one of certain selected organic substrates in equimolar quantities in an ethereal solvent. - 2 46141 According to the present invention, there is provided a process for polymerizing a compound containing at least one non-aromatic system of conjugated carbon-carbon double bonds, which comprises contacting the monomer with, as sole catalyst, a compound produced by the reaction in an ethereal solvent of equimolar quantities of sodium and an ethylenic compound having the formula: R, R4 >cc< 3 FT κ wherein each of R1, R2, R3 and R4, which can be the same or different is a hydrogen atom or an alkyl, aryl, aralkyl or alkaryl radical, with the proviso that at least one R1, R2, R3 and R4 is selected from aryl, aralkyl and alkaryl radicals.

The fact that the present invention works is surprising as it is contrary to the expectations suggested by the above-mentioned documents; more particularly, it is against the disclosure in the United States Patent in which the alkali metal is employed in the form of an alkyl or alkenyl derivative. ? Ί 4 Preferably at least two of R , R , R and R are selected from 12 3 4 aryl, aralkyl and alkaryl radicals, any other radical R , R , R or R being a hydrogen atom or an alkyl radi cal.

A particularly advantageous embodiment of the present invention is when the ethylenic compound used to form the product of the interaction with sodium is stilbene, tetraphenyl ethylene, 1,1-diphenylethylene or 1,1,2triphenylethylene.

The interaction reaction between Na and the ethylene derivative preferably takes place in the range from -78°C to +70°C, more preferably at a temperature in the range from 0°C to +30°C, in a polar ethereal solvent, more preferably in tetrahydrofuran (hereinafter abbreviated to THF), methyl-THF, - 3 46141 dioxane, diethyl ether, dimethyl ether, dibutyl ether, diethyleneglycoldiethyl ether, or diqthylene glycol dimethyl ether, or a mixture of any two or more thereof.

The product of this reaction can be used as such in the polymerization, possibly together with other solvents, in order to have a particular influence on the molecular weight and/or on the microstructure.

The polymerization is preferably carried out at a temperature in the range from -50°C and + 100°C, usually under a pressure of at least atmospheric pressure.

The polymerization solvent may be selected from, for example, polar compounds and mixtures of aliphatic, cycloaliphatic or aromatic compounds with polar compounds.

The monomers to be polymerized in the process according to the present invention are those which contain at least one non-aromatic system of conjugated carbon-carbon double bonds, such as butadiene, isoprene, piperylene, - Cg fractions of compounds containing at least one system of conjugated carbon-carbon double bonds and, lastly, mixtures of monomers of the conjugated diolefin type.

As compared with conventional polymerization processes and more particularly with that using Na naphthalene as catalyst, the process according to the present invention has the following advantages: 1. Improved stability of the catalyst, with respect to time (thus, the Na-stilbene system is stable for a few days at room temperature) and with respect to temperatures of up to 60°C - 70°C. 2. Higher polymeric yields with the same quantity of alkali metal contained in the catalytic system, the other polymerization parameters being equal (a mole percent of catalyst relative to the monomer in the range from 0.H to 5% is generally sufficient). 3. Shorter polymerization times for obtaining a substantially complete conversion (from 10 minutes to one hour, the other parameters being equal). - 4 46141 4. A wider versatility of the catalytic system in regulating the molecular weight (according to the type of solvent used); there can be obtained oligomers with a molecular weight of from 500 to 2,000 when working in toluene, or polymers having a high molecular weight.

°C ( Γ n _7tx = 0.5) when working in THF; intermediate viscosity values can be obtained by operating with mixtures of the two solvents.

. The possibility of controlling the micro-structure of the polymer obtained, and more particularly the possibility of obtaining high contents of 1,2- in the case of the polybutadiene, and high 3,4- in the case of polyisoprenes. The vinyl-addition contents can be varied, however, according to the nature of the solvent and consistently with the intended practical uses.

The following Examples illustrate the present invention.

EXAMPLE 1.

(A) The polymerization catalyst was prepared by reacting 10 millimoles of stilbene with an equimolar quantity of finely divided metallic sodium in 70 ml of THF and by keeping the reaction mixture stirred at 25°C for 5 hours. The mixture was then filtered and titrated. The yield relative to the reacted Na was 95%.

(B) 2 Millilitres of the anhydrous solution in THF (containing 0.2 millimole of the catalytic system), prepared as specified in (A), were placed in a bottle stoppered with a crown-cap. which bottle had been deaerated and nitrogen-purged at a temperature of 25°C. There were then added 18 ml of anhydrous toluene, the bottle was stoppered and there were then introduced by injection 2.8 grams of buta-1,3-diene (50 millimoles).

After 30 minutes, the polymerization mixture was treated with a 1:1 solution of water and methanol in a separating funnel, and the supernatant - 5 46141 layer was recovered and evaporated to dryness.

There were obtained 2.8 grams (yield = 100%) of a polymer having a liquid consistency (mol. wt, 800), the microstructure of which was as follows: 1,2- =84.7%; 1,4- = 15.3%; and 1,4-cis = 0%.

EXAMPLE 2.

In a bottle equipped with a crown cap stopper, which has been deaerated and purged with nitrogen, there were placed 2 ml of a solution of catalyst in THF (0.2 millimole of catalyst), prepared as in Example 1 (A).

There v/ere then added 2 ml of THF and 16 ml of toluene; the bottle was sealed and there were introduced by injection 2.8 grams of butadiene (50 millimoles). After 30 minutes the polymerization mixture was treated with a 1:1 solution of methanol and water in a separating funnel, and the toluene layer was recovered and evaporated to dryness.

There were obtained 2.8 grams (yield = 100%) of a polymer having a °C Γη] =0.26 toluene and the following microstructure: 1,2- = 85%; 1,4- = 15%; and 1,4-cis = 0%.

EXAMPLE 3.

A de-aerated, nitrogen-scavenged polymerization bottle having a crown-cap stopper was charged at a temperature of 25°C with 0.2 millimole of the product of interaction of Na and stilbene, prepared as in Example 1 (A) There were then added 18 ml toluene and 5 ml isoprene (50 millimoles) The bottle was sealed and the contents stirred. After 2 hours, coagulation of the polymer with methanol was carried out.

There were obtained 2.9 grams of a polymer (yield = 85%) which had - 6 464 41 °C Γ n 1 = 0.12 toluene and the following microstructure: 3,4- = 85%; and 1.2- = 15%.

EXAMPLE 4.

A de-aerated, nitrogen-scavenged polymerization bottle which had a crown-cap stopper was charged at a temperature of 25°C with 30 milligrams (0.2 millimole relative to Na) of the interaction product of Na and stilbene (1:1) in dioxane. There were added 10 ml of diethylene glycoldimethylether and, by injection, 2,8 grams of butadiene.

After 15 minutes, the polymer was coagulated with methanol. There were obtained 2.8 grams of polymer (yield = 100%) which had °C Γ n J = 0.5 toluene and the following microstructure: 1,2-= 85%; and 1,4-trans = 15%.

EXAMPLE 5.

(A) The Na-tetraphenylethylene adduct was prepared by reacting millimoles of tetraphenylethylene with an equimolar quantity of finely divided metallic sodium in 80 ml of anhydrous THE and stirring at 25°C for 4 hours. The solution was filtered and then titrated. The yield relative to the reacted Na was 94%. Note: the reaction can be carried out also at -78°C with yields which are comparable to the above, the reaction time being the same.

(B) One millimole of catalyst solution, prepared as in (A), was placed in a bottle having a crown-cap stopper with a total volume of 20 ml of THF.

The bottle was sealed and 2.8 grams of butadiene (50 millimoles) were introduced therein by injection. After two hours the polymerization mixture was - 7 coagulated with methanol. There were obtained 2.5 grams of polybutadiene (yield = 100%) which had °C Γ n _7 = 0.9 toluene and the following microstructure: 1,2- = 90%; 1,4-trans = 10%; and 1,4-cis = 0%.

Claims (12)

1. A process for polymerizing a compound containing at least one non-aromatic system of conjugated carbon-carbon double bonds, which comprises contacting the monomer with, as sole catalyst, a compound produced by the reaction in an ethereal solvent of equimolar quantities of sodium and an ethylenic compound having the formula C = C R 2 ^ 12 3 4 wherein each of R , R , R and R , which can be the same or different, is a hydrogen atom or an alkyl, aryl, aralkyl, or alkaryl radical, with the proviso 12 3 4 that at least one of R , R , R and R is selected from aryl, aralkyl and alkaryl radicals. 12 3

2. A process according to Claim 1, wherein at least two of R , R , R 4 and R are selected from aryl, aralkyl and alkaryl radicals.

3. A process according to either preceding claim, wherein the ethylenic compound is stilbene, tetraphenyl ethylene, 1,1-di phenyl ethylene or 1,1,2triphenyl ethylene.

4. A process according to any preceding claim, wherein the interaction between the sodium and the ethylenic compound takes place at a temperature in the range from -78°C to +70°C.

5. A process according to Claim 4, wherein the temperature of the interaction is in the range from 0°C to +30°C. - 8

6. A process according to any preceding claim, wherein the interaction between the sodium and the ethylenic compound takes place in the presence of a solvent selected from tetrahydrofuran (THF), methyl tetrahydrofuran, dioxane, diethyl ether, dimethyl ether, dibutyl ether, diethylene glycol, diethyl ether, diethylene glycol dimethyl ether, or admixtures of any two or more thereof.

7. A process according to any preceding claim, wherein the polymerization is carried out at a temperature in the range from -50°C to +100°C.

8. A process according to any preceding claim, wherein the polymerization is carried out under a pressure of at least atmospheric pressure.

9. A process according to any preceding claim, wherein the polymerization is carried out in the presence of a solvent selected from polar compounds or mixtures of aliphatic, cycloaliphatic or aromatic compounds with polar compounds.

10. A process according to any preceding claim, wherein the monomer to be polymerized is butadiene, isoprene, piperylene, a C^ - Cg fraction of compounds containing at least one system of conjugated carbon-carbon double bonds, or a mixture of two or more thereof.

11. A process according to Claim 1, substantially as described in any foregoing Example.

12. A polymer whenever produced by a process according to any preceding claim.