OPTIMIZATION OF 2-CHLOROETHYLPHOSPHONIC A CID SYNTHESIS BY ACID-HYDROLYSIS OF DIALKYL-2-CHLOROETHYLPHOSPHONATE COMPOUNDS - INFLUENCE OF THENATURE OF ALKYL PHOSPHONATE FUNCTIONS

Optimization of 2-chloroethylphosphonic acid synthesis by acid hydroly sis of dialkyl-2-chloroethylphosphonate compounds. Influence of the na ture of alkyl phosphonate functions. 2-Chloroethylphosphonic acid (eth ephon) 1 is very much used in agriculture as a plant regulator. It is an especially good stimulant used to increase the latex production of Hevea brasiliensis. Ethephon is generally obtained by HCl hydrolysis o f bis(2-chloroethyl)-2-chloroethylphosphonate, previously prepared by Arbuzov rearrangement of tri(2-chloroethyl)phosphite. However, because of the low reactivity of 2-chloroethylphosphonate functions towards a cid hydrolysis, this synthetic way is not convenient to prepare pure 2 -chloroethylphosphonic acid with high yields. The present purpose was to study the hydrolysis of various dialkyl-2-chloroethylphosphonates i n view to define an efficient synthetic protocol, leading to very pure crystallized ethephon with high yields.