Improved process for preparing metal alkoxide compounds

A process for preparing a compound of the formula MOR2 by reactive distillation, wherein:

• (a) a stream S1 comprising a compound of the formula MOR1 is fed via a lateral feed into a reactive distillation column RR with a rectifying section V above the feed point and a stripping section A below the feed point;
• (b) a stream S2 comprising a compound of the formula R2OH is fed into the stripping section A, the bottom and/or a bottoms circuit of the column RR,
• which affords, in the stripping section A, a crude product comprising MOR2, R2OH, R1OH, and, in the rectifying section V, a vapour B1 comprising R1OH;
• (c) a stream SU of a solution of MOR2 in R2OH is drawn off at the bottom of the column RR and/or from the bottoms circuit;
• (d) the vapour B1 is drawn off at the top of column RR as vapour stream SO comprising R1OH, vapour stream SO is at least partly condensed, giving a condensate KO at a temperature TKO, and the whole condensate KO is returned as reflux stream SKO to the rectifying section V of column RR;
• (e) in the column RR, the condensate KO is contacted with the vapour B1, such that energy is transferred from the vapour B1 to the condensate KO, which affords a condensate K1 comprising R1OH at a temperature TK1, where TKO<TK1;
• (f) and at least a portion of K1 is withdrawn from the rectifying section V below the feed of SKO into RR as liquid sidestream SK1;
• wherein:
• M is a metal;
• R1 is an alkyl radical optionally having one or more hydroxyl groups, or a haloalkyl radical optionally having one or more hydroxyl groups;
• R2 is an alkyl radical optionally having one or more hydroxyl groups, or a haloalkyl radical optionally having one or more hydroxyl groups;
• for R1 and R2, the carbon chain of the alkyl radical or haloalkyl radical may be interrupted by one or more oxygen atoms, wherein there are at least two carbon atoms between said oxygen atoms and any hydroxyl group of R1 or R2;
• and wherein R1 and R2 are different.