| abstract |
1,1-disubstituted ethylene compounds of the general formula I ##STR1## where Z is COOR 2 , CN or COR 3 , R 1 is an aliphatic, cycloalophatic, araliphatic, aromatic or heterocyclic radical which may be further substituted by functional groups which are inert under the reaction conditions, R 2 is an aliphatic, cycloaliphatic or araliphatic radical of 1 to 15 carbon atoms and R 3 is an aliphatic, cycloaliphatic or araliphatic radical of 1 to 15 carbon atoms which may be substituted by groups which are inert under the reaction conditions, and R 1 together with R 2 or R 1 together with R 3 may furthermore form an alkylene chain of 2 to 10 carbon atoms which may be substituted by groups which are inert under the reaction conditions, are prepared from a formyl compound of the general formula II ##STR2## where Z, R 1 , R 2 and R 3 have the above meanings, by a process in which the reaction is carried out in the presence of formaldehyde or paraformaldehyde and n (a) a C 1 -C 12 -alkanol or n (b) a mixture of a C 1 -C 12 -alkanol and water or n (c) with water in the presence of a secondary amine and a protic acid n at from 0° to 200° C. |