Arbeiten über Phosphorsäure‐ und Thiophosphorsäureester mit einem heterocyclischen Substituenten. 5. Mitteilung . 2‐Alkoxy‐ und 2‐Alkylthio‐5‐chlormethy1‐‐1, 3,4‐thiadiazole, 2‐Alkyl‐ 5‐chlormethy1‐1,3,4‐oxadiazole und daraus hergestellte Thio‐ und Dithiophosphorsäure‐O, O‐dialkyl‐S‐[(2‐alkoxy‐ und 2‐alkylthio‐1, 3, 4‐ thiadiazol‐5‐yl)‐methyl]‐ bzw. ‐S‐[(2‐alky1‐1, 3, 4‐oxadiazol‐5‐yl)‐methyl‐ester

2‐Alkoxy‐5‐chloromethy1‐1,3,4‐thiadiazoles are prepared by ring closure of 3‐chloroacetyl‐thiocarbazic acid O‐alkyl esters with concentrated sulfuric acid, 2‐alkylthio‐5‐chloro‐methy1‐1,3,4‐thiadiazoles directly from dithiocarbazic acid alkylesters with chloroacetylchloride in benzene in a one step synthesis omitting the 3‐chloroacetyl‐derivatives and 2‐alkyl‐5‐chloro‐methy1‐1,3,4‐oxadiazoles from 1‐chloroacetyl‐2‐acyl‐hydrazines with POCl 3 . These three types of chloromethyl heterocycles easily react with salts of thio‐ and dithiophosphoric acids to form the corresponding O,O‐dialkyl‐S‐[(2‐alkoxy‐ and 2‐alkylthio‐1,3,4‐thiadiazol‐5‐yl)‐methyl]‐ and ‐S‐[(2‐alky1‐1,3,4‐oxadiazol‐5‐yl)‐methyl]‐thio‐ and ‐dithiophosphates.