Patent GB-601807-A (GB)
Title: Manufacture of vinyl esters and polymers and interpolymers derived therefrom
IPC: C07C69/74
Filed: 1945-12-10
Abstract: Monomeric vinyl esters are prepared by reacting acetylene with a fluorine containing carboxylic acid comprising a saturated four-carbon atom ring having a carboxyl radical and at least two fluorine atoms attached directly to said ring.  Examples of suitable acids are tetrafluoro-, tetrafluoromonochloro-, trifluoro-monochloro-, difluoro-dichloro-, difluoromonochloro-, trifluoro-monobromo-, difluoro-, methyl tetrafluoro-, ethyl monochloro-trifluoro- and methylmonochloro-trifluoro-cyclobutane carboxylic acids.  The process is preferably effected in the liquid phase in the presence of a mercury salt as catalyst.  The latter may suitably be a mixture of mercuric oxide and mercuric sulphate or other mercuric salt.  Inert solvents such as benzene or other aromatic or aliphatic hydrocarbons can be used to dilute the reaction mixture.  The monomeric compounds may be polymerized alone or with one or more polymerizable compounds, which contain at least one ethylenic linkage, e.g. alpha-methylene carboxylic acids, such as acrylic and methacrylic acids, their monohydric alcohol esters such as methyl acrylate, methyl methacrylate and butyl methacrylate, acrylamide and methacrylamide, acrylonitrile and methacrylonitrile, vinyl carboxylates such as vinyl acetate, vinyl isobutyrate, vinyl laurate and vinyl benzoate, vinyl halides such as the chloride, bromide and fluoride, styrene, methyl vinyl ketone, methyl isopropenyl ketone, butadiene, isoprene and other diene hydrocarbons, N-vinyl imides such as N-vinyl phthalimide and N-vinyl succinimide, polyhalogenated ethylenes, such as unsymmetrical dichloroethylene, difluoroethylene, trifluoroethylene, trifluorochloroethylene and tetrafluoroethylene and esters of itaconic acid, and polyfunctional compounds, e.g. the polyhydric alcohol esters of methacrylic and acrylic acids such as ethylene glycol dimethacrylate, hexamethylene glycol dimethacrylate, dimethallyl carbonate, ethyidene dimethacrylate, and hexamethylene dimethacrylamide.  The monomeric ester may also be polymerized with a mixture of other of said vinyl esters.  Polymerization may be effected by the bulk, solution, emulsion and granulation processes and the temperature is preferably 40 DEG  to 60 DEG  C.  The air in the systems and in the free space above the mixtures is advantageously displaced with an inert atmosphere such as nitrogen or carbon dioxide.  In the bulk method the monomers are polymerized in the absence of a solvent or diluent by means of a polymerization catalyst such as benzoyl peroxide, lauroyl peroxide and diethyl peroxide.  Ultraviolet light may be used with the catalyst or in lieu thereof and photopolymerization catalysts such as benzoin or diacetyl may be used with ultraviolet light in the presence or absence of peroxide type catalysts as in Specification 567,778.  In the solution method polymerization is effected in a solvent such as alcohol, benzene, acetone, toluene, dioxane or ethyl acetate in the presence of a common polymerization catalyst soluble in the solvent.  Ultraviolet light may be used with or without a catalyst and a photopolymerization catalyst such as benzoin or diacetyl may also be employed.  The monomer may be polymerized by the emulsion method, as described in Specification 544,341.  An emulsion system comprising ammonium persulphate or an alkali persulphate as catalyst, an oxidisable oxygen-bearing sulphur compound as a promoter and the sodium salt of a long chain hydrocarbon sulphonate or a long chain alcohol sulphate as the dispersing agent, is, however, preferred. Suitable promoters mentioned are sulphur dioxide, sodium bisulphite, sodium sulphite, ammonium bisulphite, sodium hydrosulphite, sodium thiosulphate, soluble salts of thionic acids, and p-toluene sulphinic acid.  The granular method may be effected as described in Specification 544,341 and stirring is essential.  The polymers may be isolated in the emulsion method, e.g. by spraying the dispersion into a heated and/or evacuated chamber or by cooling the dispersion below the freezing point of the aqueous medium or by adding a large volume of a lower aliphatic alcohol such as methanol or ethanol.  A preferred method is to precipitate the polymer by adding a solution of an electrolyte, e.g. sodium chloride, sodium sulphate, hydrochloric acid, phosphoric acid, calcium chloride, magnesium sulphate, lead nitrate, lead acetate, stannous chloride and aluminium sulphate to the diluted aqueous dispersion with rapid agitation at a temperature just below the point at which the precipitated particles tend to cohere.  The polymers may be used for films, adhesives and impregnating and coating compositions.  In examples: (1) a mixture of tetrafluorocyclobutane carboxylic acid, benzene, mercury sulphate, mercuric oxide, and hydroquinone is treated with acetylene at 50 DEG C. to obtain the vinyl ester of the acid; (2) the ester produced in (1) is polymerized by heating with benzoyl peroxide; (3) the same monoester is interpolymerized with methyl methacrylate, vinyl acetate and acrylonitrile respectively by heating in the presence of benzoyl peroxide.ALSO:Monomeric vinyl esters are prepared by reacting acetylene with a fluorine containing carboxylic acid comprising a saturated four-carbon-atom ring having a carboxyl radical and at least two fluorine atoms attached directly to said ring.  Examples of suitable acids are tetrafluoro-, tetrafluoromonochloro-, trifluoro-monochloro-, difluoro-dichloro-, difluoromonochloro-, trifluoro-monobromo-, difluoro, methyl tetrafluoro-, ethyl monochlorotrifluoro and methyl-monochloro - trifluoro - cyclobutane carboxylic acids.  The process is preferably effected in the liquid phase in the presence of a mercury salt as catalyst.  The latter may suitably be a mixture of mercuric oxide and mercuric sulphate or other mercuric salt.  Inert solvents such as benzene or other aromatic or aliphatic hydrocarbons can be used to dilute the reaction mixture.  In an example, a mixture of tetrafluorocyclobutane carboxylic acid, benzene, mercury sulphate, mercuric oxide, and hydroquinone is treated with acetylene at 50 DEG  C. to obtain the vinyl ester of the acid.  The acids specified as starting materials may be obtained by heating at a temperature between 50 DEG  C. and that at which decomposition of the reactants and product occurs, a monomeric polyfluoroethylene, which is stable against polymerization on standing under pressure at 25 DEG  C., with a functional derivative of an unsaturated carboxylic acid containing a terminal methylene group and hydrolysing the product.  Thus, tetrafluoro cyclobutane carboxylic p  acid is obtained by heating acrylonitrile with tetrafluoroethylene and hydrolysing the resultant 1-cyano-2,2,3,3-tetrafluorocyclobutane.