Patent GB-581501-A (GB)
Title: Improvements in or relating to the production of vinyl esters
Filed: 1944-07-28
Abstract: Vinyl, including substituted vinyl, esters are produced by reacting an acetylene with a carboxylic acid in the vapour phase at an elevated temperature in contact with a catalyst comprising an oxide of at least one of the metals Zn, Mg and Mn in chemical combination with an oxide of one of the metals Cr, V, W and Mo. Readily reducible oxides of hydrogenating metals including Cd, Hg, Cu, Ag, Sn, Pb, Bi, Fe, Co and Ni may also be present in chemical combination.  Preferred catalysts comprise zinc chromite with minor quantities of chromite of cadmium or cadmium and mercury. The catalysts may be prepared by addition of ammonium chromate or ammonium dichromate and ammonia to give a pH of 7.1-7.2 to solutions of the metal salts, and decomposition of the chromates at 400 DEG  C.  They may be used on carriers such as silica, alumina, pumice and asbestos, and binders such as ammonium dihydrogen phosphate, boric or silicic acid may be incorporated.  They may be reactivated by steaming and burning.  Any acetylene of the formula RC­CR1, where R and R1 are hydrogen or saturated or unsaturated hydrocarbon radicals, may be reacted, for example, acetylene, mono- and di - vinyl acetylenes, allylene, butyne-1, 3-octene-1-yne and 1-pentene-3-yne.  Carboxylic acids include saturated fatty acids, substituted, unsaturated and cyclic monocarboxylic acids and polycarboxylic acids, for example, acetic up to arachidic acids, cysteine, methoxyacetic, phenyl acetic, phenyl glycine, chloracetic, pyruvic, thioglycollic, and meththioglycollic acids, acrylic, methacrylic, crotonic, cinnamic, oleic, linoleic, undecylenic, benzoic, toluic, salicylic, furoic, tetrahydrofuroic, pyridine and quinoline carboxylic acids, and succinic, maleic, fumaric, pimelic, glutaric, adipic, and phthalic acids.  Temperatures of 100-350, preferably 200-350 DEG  C. are employed generally at normal pressure. The acid may be prevaporized and passed with acetylene through a reaction tube at a space velocity of up to 500 or more, usually 400-500 vols. of gas/vol. of catalyst/hr.  The molar ratio of acetylene to acid is generally 0.5-3.0.  The vinyl esters are separated from the condensed products by distillation.  They are used in making resins and film-forming polymers as intermediates, modifying and dispersing agents, as fabric finishing agents, rubber substitutes and insecticides.  In examples: (1) and (2) a zinc-cadmium-mercury chromate catalyst is heated to 175 DEG  or 215 DEG  C. and contacted with acetylene and acetic acid vapours to yield vinyl acetate; (3) zinc-cadmium chromite heated to 215 DEG  C. is used similarly; (4) vinyl n-butyrate is made similarly with the same catalyst heated to 220 DEG  C.; (5) vinyl diethylacetate is made using zinc-cadmium-mercury chromite; (6) to (10) zinc-cadmium chromite is used to produce vinyl acetate from acetylene and acetic acid in various molar ratios at different space velocities; (11) zinc chromite heated to 238 DEG  C. is used similarly; (12) to (14) zinc-cadmium chromite containing ammonium dihydrogen phosphate, boric acid or sodium silicate as binder is used.  The increased yield after reactivation is shown; (15) zinc-cadmium-mercury chromite is used at 215 DEG  rising to 260 DEG  C.