Patent GB-663201-A (GB)
Title: Production of thioether esters and compositions containing the same
IPC: C08L27/06
Filed: 1948-12-18
Abstract: Polyesters of monothio-polycarboxylic acids (prepared by adding hydrogen sulphide to esters of a b -unsaturated di- and poly-carboxylic acids-(see Group IV (b)) are used as plasticizers for cellulose acetate and other cellulose esters, and for vinyl resins such as polyvinyl chloride, vinyl chloride-acetate copolymers and vinyl chloride-vinylidene chloride copolymers. Suitable compositions are: (1) tetraethyl, tetrabutyl or tetrahexyl thiodisuccinate with vinyl chloride-acetate copolymer and dibutyl tin dilaurate, and (2) tetrabutyl thiodisuccinate with vinyl chloride-acetate copolymer, litharge and lead stearate. Other suitable plasticizers are tetra-isopropyl thiodisuccinate, tetra-2-ethylbutyl thiodisuccinate, tetramethyl thiodisuccinate, tetrabenzyl thiodisuccinate, tetra-methoxyethyl thiodisuccinate and hexaethyl and hexabutyl thioditricarballylates.ALSO:Polyesters of monothio-polycarboxylic acids are obtained by condensing hydrogen sulphide with at least two mols. of at least one polyester of an a b -unsaturated olefinic carboxylic acid; the esters so produced have at least 12 carbon atoms, and may be hydrolysed to the corresponding acids which have at least 8 carbon atoms.  The reaction may be carried out at 150-300 DEG C., preferably under pressure, or alternatively at 0-100 DEG  C. in the presence of a strong organic base as catalyst at atmospheric pressure or above.  Suitable catalysts are piperidine, 2 : 5-dimethylpiperazine, sec.- and tert.-aliphatic amines such as di- and tri-ethylamine and di-isopropylamine, and quaternary ammonium bases such as trimethylbenzylammonium hydroxide. Primary amines, weaker organic bases and inorganic bases are unsuitable.  A solvent inert to the reactants is preferably used, e.g. ethanol, butanol, diethyl ether, glycol ethers, dioxane, benzene.  The first product of the reaction is a mercapto-ester formed from 1 mol. each of the reactants, and this then reacts with a second mol. of the unsaturated ester to give the thio-polyester; the second reaction is faster than the first. Examples show the preparation of the following tetra-esters of thiodisuccinic acid: methyl, butyl, n-hexyl, 2-ethylhexyl, 5-ethyl-2-nonanyl, beta-methoxyethyl, beta-phenoxyethyl, betachloroethyl, 2-ethylbutyl, allyl and benzyl; also of tetrabutyl thiodi-(a -methylsuccinate) and hexaethyl and hexabutyl thiodi-tricarballylates.  The hydrolysis of tetramethyl thiodisuccinate to the corresponding acid is also described. Tetraethyl thiodisuccinate, tetra-(2-ethylbutyl) thiodisuccinate and tetra-(2 : 6-dimethyl-4-heptyl) thiodisuccinate are also mentioned. The starting materials may be esters of maleic, fumaric, methylenemalonic, ethylidenemalonic, citraconic, mesaconic, ethylmaleic, aconitic and a - and g -alkyl-aconitic acids.  The esterifying groups may be, in addition to those specified above, cyclohexyl, methoxyethoxyethyl, phenoxyethoxyethyl, beta-bromoethyl or vinyl.  The Specification as open to inspection under Sect. 91 is not limited as regards proportions of reactants, and also states that any basic catalyst may be used, ammonia, sodium hydride and sodium butoxide being specified in addition.  This subject-matter does not appear in the Specification as accepted.