Patent GB-592172-A (GB)
Title: Improvements in or relating to complex monomeric esters and the production thereof
IPC: C11C3/04
Filed: 1944-04-11
Abstract: Esters are produced by esterifying a chloroformate of an unsaturated alcohol ester of a simple monohydroxy carboxylic acid with a glycol or glycerol or a polychloroformate of a glycol or glycerol with an unsaturated alcohol ester of a simple monohydroxy carboxylic acid in the presence of an acid acceptor, e.g. pyridine or other tertiary cyclic amine or a carbonate oxide or hydroxide of an alkali or alkaline earth metal.  The new esters have the formula <FORM:0592172/IV/1> where RH is the organic radical derived from the glycol or glycerol which has Y hydroxy groups, RHA is the residue derived from the monohydroxy carboxylic acid and linking one hydroxy group and at least X carboxyl groups, and RU is the residue derived from the unsaturated alcohol, X being a small integer and Y being 2 or 3.  A simple monohydroxy carboxylic acid is defined as having one hydroxy group and at least one carboxyl group, but does not include compounds having an ester linkage such as lactyl lactic acid or castor oil or glycol mono- or di-lactate.  Acids specified are glycolic, lactic, ethylene lactic, a - and b -hydroxybutyric, salicylic phloretic, melilotic, coumaric, coumarinic, vanillic, leucinic, valerolactinic, acetonic, ricinoleic, tartronic, malic, itamalic, isomalic, citromalic, citric and hydroxy phthalic acids. The glycol or glycerol may be ethylene, propylene, trimethylene and tetramethylene glycols, dihydroxy butane and pentane, ricinoleyl alcohol, polyglycols such as di-, tri- and tetra-ethylene, propylene and butylene glycols or glycerol. Esters of unsaturated alcohols having up to 5 carbon atoms and an unsaturated linkage in an aliphatic chain are preferred, e.g. vinyl, allyl, methallyl, chlorallyl, crotyl, tiglyl, chlorcrotyl, ethylallyl, propargyl and angelyl alcohols, and methyl vinyl, methyl allyl, ethyl vinyl, divinyl and dimethyl vinyl carbinols. Others of 6-10 carbon atoms or more than 10 are specified, viz. geranyl, citronellyl, cinnamyl, phenyl propargyl and b -propylallyl alcohols, and diallyl, ethyl methallyl, and ethyl divinyl carbinols, and linoleyl, oleyl and furfuryl alcohols.  The polychloroformate of the glycol or glycerol may be added to the unsaturated ester such as allyl lactate, divinyl tartronate or methallyl salicylate and the acid acceptor, preferably at 0-10 DEG  C. Temperatures of, for example, 50-80 DEG  C. may be required with slightly soluble alkali such as calcium carbonate. Alternatively, the unsaturated alcohol ester such as chlorallyl leucinate, vinyl glycolate or triallyl citrate may be treated with phosgene at 0-20 DEG  C. and the chloroformate treated with the glycol or glycerol.  The new esters are used as plasticizers for styrene, cellulose, vinyl, urea, protein, phenolic or acrylic resins, solvents, insecticides and coating compositions.  They may be polymerized to a fusible intermediate stage and finally to an infusible, insoluble polymer.  Polymerization may be interrupted at the gel stage to free the polymer from the mould and relieve strain. This initial polymerization is effected at a sufficiently low temperature to prevent complete decomposition of the peroxide catalyst.  The gel may be coated with monomer or syrupy polymer and polymerization completed.  More advanced polymers may be made from the gel which can be shaped after heating.  The monomer with 1-5 per cent of organic peroxide may be thickened by heating and polymerized by heating at 70-100 DEG  C. between plates separated by compressible gaskets.  Pressure is maintained by clamps to prevent shrinkage. Alternatively, polymerization may be suspended while the material is still liquid and fusible polymer separated or fusible polymer separated from gel as described in Specification 595,061 and copolymerized and utilized as disclosed therein.  The monomeric esters may also be mixed with fillers, e.g. magnesium carbonate, cellulose or asbestos, to give moulding powders which may be obtained dry by precuring at 50-70 DEG  C. for, say, 1-3 hrs. In examples: (1) allyl salicylate, made by refluxing salicylic acid, allyl alcohol, benzene and p-toluene sulphonic acid monohydrate, is treated with 1/2 molar proportion of ethylene glycol bis-chloroformate while in solution in pyridine and benzene at 5-15 DEG  C.  The ester obtained gives a transparent polymer on heating with benzoyl peroxide at 80 DEG  C.; (2) methallyl alcohol and salicylic acid are reacted in presence of benzene and the ester treated in presence of caustic soda with dipropylene glycol dichloroformate made by treating the glycol with phosgene at 0 DEG C.; (3) allyl salicylate in benzene is saturated with phosgene at - 2 DEG  to 5 DEG  C. and the solution added to diethylene glycol and pyridine at below 15 DEG  C.  The ester is heated in benzene with acetyl peroxide and the viscous solution poured into alcohol to give a gummy precipitate which is pressure moulded and polymerized; (4) ethylene glycol dichloroformate is added to allyl lactate and pyridine at 2 DEG  C.  The ester is polymerized by heating with acetone peroxide; (5) methallyl glycolate, made by refluxing the acid and alcohol, is treated with phosgene at below 8 DEG  C., and the chlorformate added to propylene glycol in presence of pyridine and benzene.  The ester is polymerized in a manner similar to that of (3); (6) a -hydroxy butyric acid is esterified with crotyl alcohol and treated with trimethylene glycol bis-chloroformate in presence of benzene and caustic soda; (7) allyl lactate, made by esterification in presence of p-toluene sulphonic acid and carbon tetrachloride, is treated with diethylene glycol dichloroformate and pyridine.  The ester is polymerized; (8) methallyl lactate chloroformate is reacted with triethylene glycol in presence of pyridine; (9) glycolic acid is refluxed with chlorallyl alcohol, phenolsulphonic acid, and benzene, and the ester formed reacted with dipropylene glycol in presence of caustic soda.  The product is polymerized by a method similar to that of (3); (10) allyl ricinoleate is reacted with ethylene glycol dichloroformate; (11) methallyl ricinoleate chloroformate is reacted with glycerine; (12) propargyl ricinoleate chloroformate is esterified with diethylene glycol.