Patent GB-811529-A (GB)
Title: Dithiophosphoric acid esters and their preparation
IPC: C07F9/165
Filed: 1956-10-11
Abstract: The invention comprises dithiophosphoric acid esters of the formula <FORM:0811529/IV (b)/1> in which R stands for an alkyl radical having one to five carbon atoms, A and B each stand for an alkylene chain containing one to three carbon atoms and Ar stands for a phenyl or substituted phenyl radical.  Substituents which may be present in the phenyl radical include halo-, and nitro radicals and lower alkyl radicals containing one to five carbon atoms.  Specific compounds mentioned include the O,O-dimethyl, O,O-diethyl, O,O-dipropyl and O,O-diamyl-dithiophosphoric acid esters which carry as an ester radical at the thiol-sulphur the 2-benzyl - mercaptoethyl - 1) -, benzyl - mercaptomethyl -, (2 - p - methylbenzylmercaptoethyl-1) -, (2 - p - chloro - benzylmercaptoethyl - 1)-, (2 - p - nitrobenzylmercaptoethyl - 1) -, (2 - (3-chloro - 4 - nitrobenzylmercapto) ethyl - 1)-, (3 - benzylmercaptopropyl - 1)-, 2 - benzylmercapto - 2 - methylethyl - 1)-, phenethylmercaptomethyl, (2 - phenethylmercaptoethyl-1)-, (2 - p - chlorophenylethylmercaptoethyl-1)-, (2 - p - nitrophenylethylmercaptoethyl - 1)-or (2 - phenylpropyl - mercaptoethyl - 1) group.  The above compounds may be obtained in a process analogous to that of United States Specification 2,759,010 by reacting the corresponding aralkylmercaptoalkylhalide with the appropriate O.O-dialkyldithiophosphoric salt, e.g. an ammonium or metal salt or the free acid in the presence of acid binding agents preferably in the presence of inert organic solvents at elevated temperatures.  Alternatively in a process analogous to that of German Specification 1,010,960 the free O,O-dialkyl-dithiophosphoric acid may be reacted with the aralkylmercaptoalkyl halide and the hydrogen halide produced allowed to escape or thiophosphoric acid ester halides may be reacted with appropriate mercaptans.  In an example O,O-diethyl-S-benzylmercapto ethyl dithiophosphate is obtained by adding b -chloroethyl-benzyl-thioether to a suspension of diethyl-dithiophosphoric acid ammonium salt in butanol at 90 DEG  C. O,O-Dimethyl - S - benzylmercapto ethyl - and S-phenylethylmercapto ethyl - dithiophosphates, O,O - diethyl - S - p - chlorobenzylmercaptoethyl -, S - m - nitrobenzylmercapto - isopropyl and S - p - xylyl mercaptomethyl dithiophosphates and O,O - dipropyl - S - benzylmercaptomethyl dithiophosphate are prepared by analogous processes.  Specification 795,340 also is referred to.ALSO:Insecticidal compositions comprise dithiophosphoric acid esters of the formula <FORM:0811529/VI/1> in which R stands for an alkyl radical having one to five carbon atoms, A and B each stand for an alkylene chain containing one to three carbon atoms and Ar stands for phenyl or substituted phenyl, e.g. phenyl substituted with halogen, a nitro group or lower alkyl group containing one to five carbon atoms (see Group IV (b)), distributed in a liquid or solid carrier.  Specific esters mentioned include the o,o-dimethyl-, o,o-diethyl-, o,o-dipropyl- and o,o-diamyl-dithiophosphoric acid esters which carry as ester radical at the thiol-sulphur the (2-benzyl-mercaptoethyl-1)-, benzylmercaptomethyl-, 2 - p - methylbenzyl - mercaptoethyl-1)-, 2 - p - chloro - benzylmercaptoethyl - 1), (2-p - nitrobenzylmercaptoethyl - 1) -, 2 - (3 - chloro - 4 - nitrobenzylmercapto) ethyl - 1 -, 3 - benzylmercaptopropyl - 1) -, 2 - benzyl - mercapto - 2 - methylethyl - 1) -, phenethyl - mercaptomethyl -, (2 - phenethylmercaptoethyl - 1) -, (2 - p - chlorophenylethylmercaptoethyl - 1) -, (2 - p - nitrophenylethylmercaptoethyl - 1) - or (2 - phenylpropylmercaptoethyl-1)-group.  Carriers mentioned include talc, chalk, bentonite, clay, water, if necessary with an emulsifier, alcohols, e.g. methanol or ethanol, ketones, e.g. acetone or methylethylketone and liquid hydrocarbons.  The products of the invention may be used in combination with each other or with known insecticides and fertilizers.  Specification 795,340 is referred to.