Through the Michaelis-Arbuzov and Related Reactions

As has already been indicated, simple vinyl halides, H2C=CHX (X = F, Cl, Br or I) do not normally undergo the Michaelis-Arbuzov reaction when heated with a trialkyl phosphite. However, in the presence of nickel(II) halides (3-10 mol%), and at 150-190 °C, reactions do take place between the halides RCH=CHX (R = H or Ph X = Cl or Br) and trialkyl phosphites which lead to dialkyl ethenyl- or (2-phenylethenyl)-phosphonates. 1-Bromo-l-phenylethene is similarly reactive to triethyl phosphite in the presence of NiBr2. Under the same conditions, ra 5-l,2-dichloroethene yields, initially, dialkyl trans-(2-chloroethenyl)phosphonate, followed by tetraethyl rra 5-(l,2-ethenediyl)diphosphonate 

The scope of the normal Michaelis-Arbuzov procedure in the synthesis of polyunsaturated phosphonic acids has not been widely explored, but it has been reported that 2-chlorobuta-1,3-diene and triethyl phosphite react together to give about 10% of the ester 220.  

In contrast to the general lack of reactivity of ethenyl halides under Michaelis-Arbuzov conditions, except in catalysis by nickel(II), the formation of bonds from phosphorus to sp -carbon is observed when polyfluoroalkenes take part in Michaelis-Arbuzov reactions. 

Michaelis-Becker reactions between sodium dialkyl phosphites and halogenated alkenes, seem to occur only with polyhalogenated alkenes, but the course of the reaction is then complicated by elimination and addition steps. Thus sodium dialkyl phosphites and 1,1,2-trichlorophenylethene react to give, ultimately, esters of (1-phenyl-1,2,2-ethane)trisphosphonic acid. Such reactions have been reviewed.  

---