Synthesis of Some 2-Chloroethylphosphonic Acid Derivatives and Their Phytoregulating Activity

摘要

2-Chloroethylphosphonic acid (CEPA) is a valuable plant growth regulator, from the group of the phytoregulators that generate ethene, widely used in various agricultural fields. Some of its derivatives are also plant growth regulating substances. The alkyl esters of 2-chloroethylphosphonic acid can be obtained by the Arbuzov reaction using trialkyl phosphates and l-halogeno-2-chloroethane. We studied an alternative way for the synthesis of these esters, through the complex formed from 1, 2-dichloroethane, PCl_3, and AlCl_3. By heating PCl_3, AlCl_3, and an alkyl chloride, in a molar ratio of 1 : 1 : 1, there were obtained complexes stable at high temperatures, having an ionic structure (Reaction 1). These complexes, reacted with alcohols, formed esters of the corresponding alkyphosphonic acid (Reaction 2). AlCl_3+PCl_3+R-Cl → [R-PCl_3]~+[AlCl_4]~- (1) [R-PCl_3]~+[AlCl_4]~-+3R'-OH → R-P(O)(O-R')_2 ·AlCl_3+R'-Cl+3HCl (2) In order to obtain 2-chloroethylphosphonates of dialkyl, we made experiments for the synthesis of the complex formed by 1, 2-dichloroethane with PCl_3 and AlCl_3 and for the reaction of this complex with 2-chloroethanol, methanol, ethanol, propanol, butanol, pentanol, i-propanol, and i-butanol. The dipropylester of CEPA was reacted with trimethylamine, triethylamine, or triphenylphosphine to give the corresponding "onium" derivatives. The biological activity of the obtained compounds was tested.