Patent GB-704879-A (GB)
Title: Insect repellent compositions
IPC: C07D307/12
Filed: 1951-01-31
Abstract: Diesters of the formula R-CH2-O-CO-(CH2)n-CO-O-R1 in which n is zero or a whole number of from 1 to 8, R is the residue of a 5-membered heterocyclic ring consisting of four carbon atoms and one oxygen atom, and R1 is an alkyl or cycloalkyl radical are produced by reacting the heterocyclic alcohol with a semi-ester chloride in the presence of pyridine; esterifying a dicarboxylic acid mono ester, in the presence of a catalyst such as sulphuric acid or toluene sulphonic acid, with the heterocyclic alcohol; re-esterifying a symmetrical dicarboxylic diester with a different alcohol, preferably in the presence of sodium ethylate or aluminium isopropylate; or esterifying the free di-carboxylic acid with a mixture of the two alcohols.  According to examples, (1) adipic acid isopropyl tetrafurfuryl diester is prepared by heating adipic acid di-isopropyl ester, tetrahydrofurfuryl alcohol and aluminium isopropylate in a distillation vessel at 160-170 DEG C.; (2) succinic acid butyl furfuryl diester is prepared by introducing dropwise a benzene solution of succinic acid chloride butyl monoester into a mixture of furfuryl alcohol, pyridine and benzene cooled to 10 DEG C.; (3) adipic acid cyclohexyl tetrahydrofurfuryl diester is prepared by heating a solution of adipic acid cyclohexyl monoester, tetrahydrofurfuryl alcohol and toluene sulphonic acid in benzene under reflux in an apparatus fitted with a water-separating device; (4) adipic acid ethyl tetrahydrofurfuryl diester is prepared by the method of example (3).ALSO:An insect repellant composition comprises a diester of the formula R-CH2-O-CO-(CH2)n-CO-O-R1 in which n is zero or a whole number of from 1 to 8, R is the residue of a 5-membered hetrocyclic ring consisting of four carbon atoms and one oxygen atom, and R1 is an alkyl or cycloalkyl radical, and at least one carrier as hereinafter defined.  The dicarboxylic acid of the ester may be oxalic, nalonic, succinic, glutaric, adipic, pimelic, suberic, azelaic or sebacic acids; the alcohol used to esterify one of the carboxyl groups may be furfuryl or tetrahydrofurfuryl alcohol; the alcohol used to esterify the second carboxyl group may be methyl, ethyl, isopropyl, n-butyl, isoamyl, or cyclohexyl alcohol or glycol monomethyl ether.  The term "carrier" means (1) a liquid or semi-liquid diluent of aliphatic or cycloaliphatic character, e.g. ethyl alcohol, isopropyl alcohol, cyclohexanol, methyl cyclohexanol, ketones such as acetone, trichlorethylene, benzine, vegetable or animal oils or fats such as groundnut oil, cocoa butter or lanoline, and mineral oils or waxes such as paraffin oil, white mineral oil or white petroleum jelly; (2) water together with an emulsifying agent; (3) a wax-like solid organic compound such as beeswax, paraffin wax and cetyl alcohol; or (4) solid inert inorganic compounds such as kaolin, or talc. Other additions such as anti-sunburn agents, perfume and the like may be present.  Specified additions are glycerine monostearate, menthyl salicylate, benzyl anthranilate, sodium cetyl sulphonate, sodium benzoate, stearic acid, glycerine, triethanolamine with oleic acid, and D.D.T.  By selecting one or more carriers and the other additions, solutions, salves, creams, oils, emulsions or powders may be obtained.