Patent GB-756489-A (GB)
Title: Improvements in or relating to new monothiophosphate esters and to pesticide compositions containing same
IPC: A01N57/12
Filed: 1954-02-15
Abstract: The invention comprises as new products O,O-dialkyl S-(1,2-dicarbalkoxyethyl) monothiophosphate esters having the general formula <FORM:0756489/IV(a)/1> in which R1, R2, R3 and R4 each represents an alkyl radical having from 1 to 4 carbon atoms.  They may be prepared by oxidizing an O,O-dialkyl S-(1,2-dicarbalkoxyethyl) dithiophosphate ester in which the alkyl and alkoxy groups have 1 to 4 carbon atoms.  The oxidation may be effected with nitric acid, hydrogen peroxide, hypochlorous acid, chromic acid, or permanganate, and is suitably carried out at 15-80 DEG  C.  Examples are given for the production of the O,O-dimethyl-, O,O-diethyl-, and O,O - di - n - propyl - S - (1,2 - dicarbethoxy-ethyl) monothiophosphates; the O,O-dimethyl-and O,O-diethyl S-(1,2-dicarbomethoxy ethyl) monothiophosphates and O,O-di-n-butyl S-(1,2-dicarbo - n - butoxyethyl) monothiophosphate from the corresponding dithiophosphate esters using strong nitric acid as oxidizing agent in each case.  The dithiophosphate starting materials may be obtained by the procedure disclosed in Specification 699,522.  The products are stated to be useful as pesticides (see Group VI) and as antioxidant petroleum additives.ALSO:A pesticide composition comprises an inert carrier and one or more O, O-dialkyl S-(1, 2-dicarbalkoxyethyl) monothiophosphates of the general formula:  <FORM:0756489/VI/1> in which R1, R2, R3 and R4 each represents an alkyl radical having 1 to 4 carbon atoms (see Group IV(b). Specified inert carriers are talc, pyrophyllite, bentonite or other inert powders or dusts and the active ingredient may be present in concentration of e.g. 0,5 to 5 per cent.  Inert liquids may also be used.  Thus aqueous suspensions or emulsions of one or more of the monothiophosphate esters at dilutions of from 1 : 1000 to 1 : 100,000 may be employed.  They may also be compounded with a suitable oil e.g. pine oil or white mineral oil and applied as an oil spray.  Examples are given to show the efficacy of the products in controlling the active stages and eggs of the two-spotted spider mite.  The products employed are O, O-dimethyl S-(1, 2 - carbethoxyethyl) - monothiophosphate-and O, O dimethyl- and O, -O-diethyl-S-(1, 2 carbomethoxyethyl) - monothiophosphates, the products being dissolved in a solvent medium consisting of 65 per cent acetone and 35 per cent water in dilutions ranging from 1 to 100,000 to 1 to 1000.  The results obtained with the same dilutions of the corresponding dithiophosphate esters (see Specification 699,522) are also given and a table is given to illustrate the superiority of the monothiophosphate esters.  The use of each of the specified esters and of O, O-diethyl S-(1, 2 - dicarbethoxyethyl) monothiophosphate in conjunction with pyrophyllite is also referred to.  The monothiophosphate esters may also be employed in fly sprays and, in suitable solvents, for the impregnation of textiles to render them insect repellent.  The monothiophosphate esters are stated to be soluble in acetone, cyclohexanone, isophorone, methyl ethyl ketone, methyl isobutyl ketone, lower aliphatic monohydric alcohols, ketone alcohols such as diacetone alcohol, various esters viz., the acetates, phthalates, abietates, fumarates and maleates, and in aromatic hydrocarbons such as benzene, toluene, and xylene.