Patent GB-395478-A (GB)
Title: Improvements in the manufacture and production of vinyl esters of higher fatty acids
IPC: C08F18/10
Filed: 1932-04-23
Abstract: Vinyl esters of carboxylic acids containing at least 5 carbon atoms in the molecule, i.e. of aliphatic, saturated and unsaturated, mono-and polycarboxyclic acids containing at least 5 carbon atoms in the molecule, of cyclic, i.e. aromatic, cycloaliphatic and heterocyclic, mono-and polycarboxylic acids and of mixed aliphatic-aromatic and mixed aliphatic-cycloaliphatic mono- and polycarboxylic acids the carboxyclic groups of which may be attached to the aliphatic or to the cyclic radical, are manufactured by treating such acids with acetylene in the presence of zinc or cadmium salts of organic carboxylic acids, while working in the liquid phase, preferably under increased pressure. Suitable acids are n-valeric acid and its isomers, caprylic, lauric, palmitic, margaric, stearic, oleic, adipic, myristic, sebacic, benzoic, o-, m- and p-toluic acids, the different isomers of naphthoic acid, phenylacetic and cinnamic acids, phenylglycine, phthalic acid and monoalkyl esters thereof, e.g. the monoethyl, n- or isobutyl esters, salicylic and hydroxynaphthoic acids, pyridine and quinoline carboxylic acids, hydrophthalic and abietic acids, also partially esterified acids, natural resins of high acid value, e.g. colophony, or mixtures of acids, e.g. those obtainable by saponification of natural fats and fatty oils, e.g. coconut oil or palm kernel oil, or by oxidation of paraffin wax or montan wax.  Suitable zinc and cadmium salts are zinc acetate, stearate and benzoate and calcium benzoate.  The salts may be added as such to the acid or, preferably, prepared by dissolving zinc or cadmium oxide in the acid to be employed.  The amount of catalyst should preferably be at least 0,5 per cent (calculated as ZnO or CdO with reference to the acid employed), e.g. 0,5 to 5, preferably 2-3 per cent.  Absorptive substances, e.g. active carbon, fuller's earth or silica gel, may be added to the reaction mixture. The reaction generally takes place at 120-300 DEG  C., preferably at 160-190 DEG  C.  When the boiling point of the acid allows the reaction may be carried out without the employment of pressure, but in most cases it is preferable to work in a closed vessel under increased pressure, e.g. about 5-30, preferably 10-20 atmospheres, or at higher pressures, e.g. 40-200 atmospheres or higher provided the pressure and temperature employed lie outside the explosion range of acetylene.  In order to prevent explosions the acetylene must be diluted with inert gases, e.g. nitrogen, hydrogen, carbon monoxide, methane or ethane.  The danger of explosions may be further precluded by the addition of inert solvents, e.g. aliphatic, aromatic, or hydroaromatic hydrocarbons such as benzine, benzene, toluene, xylene, cyclohexane, or decahydronaphthalene, or esters such as the vinyl esters obtainable by the present process or such esters as methyl, ethyl, n-butyl, isobutyl or amyl acetate or butyrate.  The process may be carried out discontinuously, or continuously, e.g. by leading acetylene, diluted if desired, from bottom to top of a pressure-tight tower filed with acid in which zinc oxide is dissolved, the vinyl ester formed being withdrawn at the top of the tower while fresh acid and catalyst are introduced at the bottom.  The distillation of the vinyl esters may also be carried out continuously, and in order to prevent polymerization it is preferably carried out in vacuo while employing enamelled or copper vessels, though vinyl esters of valeric, caproic and like acids of comparatively low molecular weight may be distilled at ordinary pressure.  Polymerization inhibitors, e.g. hydroquinone, naphthols or amines, may be added during distillation or storage of the esters, or incorporated in the reaction mixture during the reaction itself.  On the other hand, the preparation and polymerization of the esters may be combined, e.g. by employing only small amounts of catalysts, e.g. less than 1 per cent, and prolonging the reaction time, or by continuing heating to 150-200 DEG  C. after the reaction is completed.  The esters may also be polymerized by methods usual in the polymerization of lower vinyl esters, e.g. by irradiation or heating or both, if desired in the presence of known polymerization catalysts such as oxygen in any form, e.g. free oxygen, organic peroxides, e.g. acetyl or benzoyl peroxide, or peracetic or perbenzoic acid, inorganic peroxides, e.g. hydrogen peroxide or barium peroxide or other inorganic agents supplying oxygen, e.g. percarbonates or perborates especially of alkali or alkaline earth metals, silver oxide or ozone, generally in an amount of about 0,1-5, preferably 0,5-2 per cent by weight of the esters, if desired together with organic acids or anhydrides, e.g. acetic anhydride, the latter being used in an amount of about 10 times the weight of the catalyst. Polymerization by heating is usually carried out by boiling the esters, preferably in an open or closed vessel under reflux or in a closed vessel without reflux.  The process may be carried out continuously by introducing monomeric compounds into the vessel and withdrawing polymerized products at the same rate.  The polymerization may be carried out in the presence of diluents, e.g. water, neutral aqueous solutions such as solutions of emulsifying agents, e.g. Turkey red oil or alkylated naphthalene sulphonic acid sodium salts, weakly acid solutions, e.g. dilute aqueous acetic acid, weakly alkaline solutions, e.g. aqueous soap solutions, or inert gases, e.g. carbon dioxide or nitrogen, if desired with the application of pressure in one or more stages, in the presence or absence of known polymerization regulators, e.g. aldehydes such as salicylaldehyde, which may also act as solvents, and of organic solvents, e.g. ethyl alcohol, benzene, methyl, ethyl or amyl acetate, chlorobenzene, carbon tetrachloride, chloroform, dichlorethylene, ketones such as acetone or cyclohexanone, or nitrated hydrocarbons such as nitrobenzene.  The polymerization may also be carried out with the aid of absorptive substances, e.g. bleaching earths or active carbon, or of organic acid chlorides, e.g. toluenesulphochloride.  The esters may also be polymerized in aqueous suspension in the presence of emulsifiers and of polymerization catalysts.  By hardening the products at 100-120 DEG  C., products useful in lacquers may be obtained.  The polymerization may be carried out only so far that the product still contains incompletely or non-polymerized constituents.  The vinyl esters may be interpolymerized with each other or with vinyl esters of lower fatty acids, e.g. vinyl acetate, chloracetate, propionate or butyrate, or with other polymerizable organic substances, e.g. vinyl halides such as vinyl bromide or chloride, styrene, acrylic esters, particularly the methyl and ethyl esters, esters of homologues of acrylic acid such as a -methylacrylic acid, acrylic nitrile, vinyl ketones such as vinyl ethyl or isobutyl ketone, or diolefines such as butadiene. The mixtures usually contain about 0,5-20, preferably 5-10 per cent of the vinyl esters of acids containing at least 5 carbon atoms.  For the preparation of interpolymerization products of vinyl esters it is possible to mix the monomeric compounds prepared separately or to prepare the mixtures by esterifying mixtures of acids.  If desired, one of the components may be incompletely polymerized, the other monomeric substance added and the polymerization then carried out to the desired degree.  The products may be employed as varnishes and lacquers, if desired together with cellulose derivatives compatible therewith such as nitrocellulose or benzyl cellulose, with or without inert fillers, e.g. slate meal, carbon black or ground asbestos, organic or inorganic pigments, e.g. white lead, colcothar, Indanthrene blue, Lithol Red lakes, organic dyestuffs soluble in lacquer solvents, and softening agents such as phthalic esters or neutral aryl phosphates.  The cellulose derivatives and other additions may also be incorporated with the monomeric esters. Polymerized vinyl esters of aliphatic open chain or cycloaliphatic carboxylic acids containing more than 12 carbon atoms may be added to polishing preparations.  In examples: (1) n-valeric acid, in which some zinc oxide is dissolved, is mixed with toluene and treated with a mixture of 2 parts of acetylene and 1 part of nitrogen at 180 DEG C. and 20-25 atmospheres pressure in an enamelled stirring autoclave, yielding n-valeric acid vinyl ester; the n-valeric acid may be replaced by caproic, caprylic, lauric or myristic acid, or by a mixture of fatty acids containing 8-12 carbon atoms obtainable by the liquid phase oxidation of paraffin wax by oxygen-containing gases; (2) palmitic acid, in which zinc oxide is dissolved, is heated in a stirring autoclave with a mixture of acetylene and nitrogen (2 : 1) at 160 DEG  C. and 15-20 atmospheres pressure, yielding palmitic acid vinyl ester; the palmitic acid may be replaced by stearic acid; (3) oleic acid similarly yields oleic acid vinyl ester; (4) commercial linoleic acid (a mixture of myristic, palmitic, stearic, arachic, oleic, linoleic and linolenic acids), in which zinc oxide is dissolved, is mixed with benzene and treated as in (2) but at 180 DEG C.; (5) cadmium or zinc oxide is dissolved in fused benzoic acid, toluene is added and the mixture treated in a stirring autoclave with nitrogen corresponding to a pressure of 5 atmospheres and acetylene of 10 atmospheres at 180-185 DEG  C., producing benzoic acid vinyl ester; the benzoic acid may be replaced by phenylacetic or a - or b -naphthoic acid, whilst zinc or cadmium salts of other organic carboxylic acids, e.g. acetic, butyric, oleic or stearic acid may, be used as catalysts; (6) phthalic acid monoethyl ester in which zinc oxide is dissolved is similarly treated to produce phthalic acid monovinyl monoethyl ester; the phthalic acid mono-ethyl ester may be r