GB595061A - Improvements in or relating to mixed esters and the preparation thereof - Google Patents

Abstract

Mixed esters of vinyl alcohol and another unsaturated alcohol and a polycarboxylic acid are prepared by reacting acetylene with a partial ester of an unsaturated alcohol containing at least 3 carbon atoms and a polycarboxylic acid in the presence of a mixture of a mercury compound, boron fluoride or boron fluorideacetic acid, and hydrogen fluoride. Esters of alcohols containing up to 10 carbon atoms and an unsaturated group in an aliphatic chain such as allyl, methallyl, crotyl, b -ethylallyl, propargyl, phenylpropargyl, cinnamyl, linalyl, dimethylallyl, methyl vinyl carbinol or citronellol are of special interest. Others specified are oleyl, ricinoleyl, linoleyl and abietyl. Specified acids are oxalic, malonic, succinic, maleic, fumaric, adipic, phthalic, tartaric and citric. Partial esters such as allyl acid oxalate, fumarate or phthalate or allyl methyl acid citrate are converted to mixed esters such as vinyl allyl oxalate or phthalate, or vinyl oleyl fumarate. The esters are used as solvents and plasticisers and may be polymerized to infusible polymers. Intermediate polymers are prepared by effecting polymerization mainly of the more active vinyl group by using low peroxide concentrations, e.g. 0.1-0.5 per cent benzoyl peroxide, or low temperatures, e.g. 40-50 DEG C. Polymerization may be interrupted at the gel stage to free the polymer from the mould and relieve strain before completing. Low temperatures such as 65-80 DEG C. for benzoyl peroxide and 140-150 DEG C. for acetone peroxide are preferred in the initial stage. Methods of minimizing polymerization on one side of a sheet and coating with monomer or syrupy polymer as described in Specifications 595,057 and 595,058 may be used. Polymerization may be suspended while the material is still liquid by cooling, adding inhibitors or removing catalyst and fusible polymer separated from all or part of the monomer by addition of non-solvents or by distillation in presence of an inhibitor. Compositions containing at least 40 per cent fusible polymer and 5-60 per cent monomer are desirable for further polymerization. A gel containing fusible polymers may similarly be treated to extract the same. These are used in particular for paints. Other fusible polymers are made by initial polymerization to a still fusible gel or by emulsifying monomer or syrupy polymer in an aqueous medium and polymerizing until the gel precipitates. Such polymers may be polymerized at elevated temperature and/or pressure with 1-5 per cent of benzoyl peroxide, generally in a heated mould. They may be mixed with fillers or pigments, e.g. cellulose, wood pulp, zinc oxide, chalk, lead chromate, magnesium carbonate and calcium silicate, plasticisers, e.g. esters of phthalic or unsaturated aliphatic acids, camphor and glycol bis-(butylcarbonates) and polymerized with phenolic, cellulose acetate, urea, vinylic, protein or acrylic resins. They are used as coating and impregnating compositions for paper, leather, wood, cloth, metal or synthetic resins and further polymerized to the insoluble, infusible state. In examples, monoallyl fumarate, succinate, adipate and oxalate are treated with acetylene at temperatures up to 45 DEG C. in the presence of mercuric oxide, boron fluoride or boron fluoride-acetic acid and hydrogen fluoride. Dioxane or dioxane and manganese dioxide may also be added. After making alkaline, the mixture is distilled or extracted with ether to recover the vinyl allyl ester. This may be polymerized by heating with 1 per cent of benzoyl peroxide at 60-70 DEG C. A 20 per cent acetone solution of vinyl allyl succinate containing 0.4 per cent benzoyl peroxide is heated at 70 DEG C. until the viscosity is doubled, poured into methyl alcohol, and the white plastic precipitate heated with benzoyl peroxide at 125 DEG C. and 2000 lb./sq. in. to give a transparent, infusible polymer.