Abstract: The present invention provides an improved process and intermediate compounds for the preparation of di-fluorovinylsilane insecticidal and acaricidal agents of the formula I wherein Ar is phenyl, 1- or 2-napthyl or a 5- or 6-membered heteroaromatic ring, each of which may be optionally substituted by any combination of from one to three halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C(O)R2 or S(O)nR3 groups, R and R1 are each independently C1-C4 alkyl or C3-C5 cycloalkyl; Ar1 is phenoxyphenyl, phenyl, biphenyl; phenoxypyridyl, benzylpyridyl, benzylphenyl, 1- or 2- napthyl or a 5- or 6-membered heteroaromatic ring, each of which may be optionally substituted by any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy or C(O)R4 groups, n is an integer of 0, 1 or 2; R2 and R4 are each independently C1-C4alkyl, benzyl or phenyl; R3 is C114 C4alkyl or C1 -C4haloalkyl; and the fluorine atoms attached to the double bond are tra