Synthesis of 1,4-polyisoprene support of 2-chloroethylphosphonic acid (ethephon), a stimulating compound for the latex production by the Hevea brasiliensis

• Published in: European polymer journal Vol. 39; no. 4; pp. 671 - 686
• Main Authors: Derouet, Daniel, Cauret, Laurent, Brosse, Jean-Claude
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2003; Elsevier
• Subjects: Applied sciences; Chemical modifications; Chemical reactions and properties; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Hevea brasiliensis; Molecular structure; Isoprene derivative polymer; Control release polymer; Phosphonic acids; Experimental study; Optimization; Operating conditions; Chemical coupling; Phosphorus polymer; Chemical modification; Dicotyledones; Preparation; Angiospermae; Epoxidation; Euphorbiaceae; Plant growth substance; Spermatophyta; Ethephon; Isoprene polymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/S0014-3057(02)00300-2

2-Chloroethylphosphonic acid (ethephon) is a well known stimulating product used to improve the latex production by the rubber tree ( Hevea brasiliensis). Its chemical fixation in side position of 1,4-polyisoprene chains by weak chemical bond was considered in order to prepare new derivatives having prolonged stimulating activity. The synthesis was considered by using a chemical modification procedure according to a two-step process. Firstly, an epoxidized 1,4-polyisoprene intermediate was prepared by partial epoxidation of 1,4-polyisoprene. Secondly, the grafting of 2-chloroethylphosphonic acid was achieved by using the reactivity of the P–OH acidic function (or a P–OSiMe 3 derived from P–OH) of the reagent toward oxirane rings of epoxidized 1,4-polyisoprene. It was noted that grafting yields are improved when the reaction is carried out in bulk or in a non-polar solvent, and more especially in neutral conditions, that is by replacing ethephon with its trimethylsilylated derivatives [monotrimethylsilyl 2-chloroethylphosphonic acid or, more especially, di(trimethysilyl) 2-chloroethylphosphonate]. With this latter, the addition occurs by the intermediate of the P–OSiMe 3 bond, and the formation of 2-oxo-l,3,2-dioxaphospholane structures is highly favored.