| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for economically preparing ethanebis(alkylphosphinic) acids in high yields. SOLUTION: (a) An element-state white phosphorus is allowed to react with an alkyl halide in the presence of a hydroxide of an alkali metal or an alkaline earth metal, (b) mineral acid is added to liberate an alkyl phosphonite, phosphorus acid and phosphinic acid, (c) the alkyl phosphonite is esterified from the mixture of an alkyl phosphonite, phosphorus acid and phosphinic acid, (d) an ester of the alkyl phosphonite is isolated from the mixture and hydrolyzed to obtain an alkyl phosphonite, and (e) the alkyl phosphonite is subjected to a free radical initiation reaction with an alkyne to prepare a corresponding ethanebis(alkylphosphinic) acid of formula (1) (wherein R1 and R2 are each H, carboxy group or the like; and R3 and R4 area each a 2-20C alkyl group).
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