Basic Alcoholysis of Metal Halides Metathesis Reaction

3 Basic Alcoholysis of Metal Halides Metathesis Reaction 

Anhydrous halogen derivatives of metals can be converted into metal alkoxides via reaction with either alkali metal alkoxides or with alcohols in the presence of ammonia. The reaction is usually carried out in other solvents than alcohols (hydrocarbon or ether ones) on cooling and with the amoimts of alcohols only slightly exceeding the stoichiometry. The reason is that oxo-alkoxides or oxo-alkoxide halides can otherwise be formed as impurities. This approach can be used successfully for synthesis of, for example, alkoxides of Sn(IV) [87], Bi (III) [114], and Fe(III) [82]  

Alkali or ammonium chloride can be removed from the reaction mixture by sedimentation of filtration. Ammonia as base is definitely preferable in case of M(IV) derivatives to help avoid formation of stable bimetallic alkoxide derivatives [59], while Ln(0 Pr)3 and M (OR)s, M = Nb, Ta can be obtained in best yields using KOR because the bimetallic species with K are least stable thermodynamically [84]. 

---