Patent GB-586520-A (GB)
Title: Improvements in or relating to carbonate esters and the preparation thereof
IPC: C08F18/08
Filed: 1944-05-17
Abstract: Diesters of carbonic acid are prepared by reacting lactic acid esters of unsaturated alcohols with phosgene, preferably in the presence of an acid acceptor such as pyridine or sodium, potassium, barium, strontium, calcium or magnesium carbonate, bicarbonate or hydroxide. Unsaturated alcohols specified are allyl, methallyl, vinyl, 2-chlorallyl, crotyl, chlorcrotyl, ethyl allyl, cinnamyl, propargyl, methyl vinyl carbinyl, oleyl, ricinoleyl, tiglyl, isopropinyl vinyl carbinyl, 3-chlorbutene-2-ol-1, 3-hydroxybutene-1, 3-hydroxypentadiene-1,4, 1 - hydroxyhexadiene - 2,4 and 1 - hydroxy - 2 - methylhexene-2, and alcohols obtained by reduction of coconut oil or chinawood oil acids.  The esters may be recovered by distillation or by washing the reaction mixture with water and drying.  They are used for solvents, paints, insecticides, pharmaceuticals, and plasticisers.  They polymerize under the action of heat, light, oxygen or peroxides to yield intermediate fusible polymers or infusible, insoluble polymers.  Polymerization may be interrupted before gel formation occurs by cooling, by adding a non-solvent to cause precipitation or by addition of inhibitors, part or all of the monomer present then being removed from the fusible polymer as by distillation or solvent extraction.  The fusible polymers may be shaped and further converted to the infusible state.  The exterior only may be converted by surface heating, applying a catalyst-containing coating, adding an inhibitor to the interior, or by varying the amounts of plasticiser in the interior and exterior. There may be incorporated plasticisers, softening agents or fillers, e.g. dibutyl or dicyclohexyl phthalate, triacetin, tricresyl phosphate, natural or synthetic resins, pigments, e.g. titanium dioxide, carbon black, chromic oxide and lead chromate, and dyestuffs such as methylene blue and methyl orange.  Copolymers containing 2-90 per cent of other polymerizable materials such as acrylates or a -substituted acrylates, e.g. methyl, allyl or glycol methacrylate, vinyl acetate, vinyl chloride, styrene, allyl esters such as allyl acetate, maleate, fumarate, phthalate, succinate, oxalate, tartrate or the corresponding vinyl, crotyl, methallyl, 2-chlorallyl or other unsaturated alcohol esters may also be produced.  The fusible polymers may be used for impregnating or coating various materials including other resins, and for making laminated products which are cured to the infusible state.  In examples: (1) phosgene is passed into a solution of allyl lactate in pyridine at below 15-20 DEG  C., the product acidified and washed; (2) methallyl lactate is treated similarly at below 10 DEG  C. to give an ester which yields a transparent solid polymer on heating for 12 hrs. at 70 DEG  C. with 5 per cent of benzoyl peroxide; (3) the ester of (2) is heated with dioxane and benzoyl peroxide at 80-85 DEG  C. until the viscosity doubled, the polymer precipitated with methanol, and further polymerized to the infusible state by heating at 150 DEG  C. and 2000 p.s.i. with benzoyl peroxide; (4) the process of (3) is repeated using the carbonate of allyl lactate; (5) vinyl lactate is made by passing acetylene into lactic acid containing mercuric oxide and boron fluoride-acetic acid, neutralizing and distilling.  The ester is dissolved in pyridine and phosgene introduced at below 10 DEG  C.