Synthesis of poly(silylenephosphonate)s incorporating 2-chloroethylphosphonic acid (ethephon), a stimulant for the latex production by the Hevea brasiliensis

2-Chloroethylphosphonic acid (ethephon) is a well-known stimulant commonly used to improve the latex production by the rubber tree (Hevea brasiliensis). In order to prolong its stimulating activity, the purpose was to insert ethephon inside polymer chains which, afterwards, will be able to degrade slowly through time, and thus to release ethephon molecules. For that, linear poly(silylenephosphonate)s incorporating ethephon groups were synthesized by using a polycondensation procedure between ethephon (or one of its dialkyl phosphonate derivatives) and an α,ω-dihalogeno-silylated monomer. To make sure that polycondensation can occur, the reactivity of halogenotrimethylsilanes (X=Cl or Br) toward ethephon and its various dialkyl phosphonate derivatives, was examined first. Then, poly(silylenephosphonate) synthesis was achieved by polycondensation between diisopropyl (2-chloroethyl)phosphonate and α,ω-dichloro-silylated monomers. According to this procedure, cyclic polymers of low average molecular weights (M_n<2000) were obtained, whatever the α,ω-dihalogeno-silylated monomer used.