Halides phosphonic acid dichloride

The reaction is performed most simply by the addition of the propargylic alcohol to a solution of the phosphorus halide. Rearrangement of the phosphorus ester proceeds at ambient temperature or with mild heating. When phosphorus trihalides are used, the product can be isolated as the phosphonic dichloride.168169 Aqueous workup provides the phosphonic acid.162 In most instances, however, a dialkyl phosphorochloridite with only a single halogen on phosphorus available for reaction with alcohol has been used.165 170 174... 

Isomerization is observed with higher alkyl halides, as in Friedel-Crafts reactions isopropylphosphonic dichloride is stated to be the sole product from n-propyl chloride,190,191 and terf-pentyl chloride undergoes C-C fission, yielding the tert-butyl acid.193 On reduction by lithium tetrahydroaluminate the phosphonic chloride formed from w-butyl chloride gives a primary phosphine that is shown by 31P-nuclear magnetic resonance to consist of n- and sec-butylphosphine in the proportions 5 95 and the product from n-octyl chloride was similarly shown to contain all four position isomers.194... 

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