Patent ID: 7273943

Claim:
Process for the preparation of high-purity metal alkoxides M(OR) x , in which M is Nb, Ta, Zr or Hf, x is 5 in the case of M=Nb or Ta and 4 in the case of M=Zr or Hf, and R independently of one another are identical or different C 1 -C 12 -alkyl radicals, wherein (a) a crude metal alkoxide product M(OR) x with a halogen content of >200 ppm, containing as impurity at least 0.05 wt. % of mononuclear or polynuclear halogen-containing metal alkoxides, is mixed with (b) at most 30 wt. % based on the total amount of crude alkoxide, of an alcohol ROH, in which R is a C 1 -C 12 -alkyl radical, and (c) subsequently or simultaneously an excess of ammonia, based on the amount of mononuclear or polynuclear halogen-containing metal alkoxides, based on the total amount of crude alkoxide, is metered in.