Abstract: The invention relates to a process for the preparation of polyorganosiloxanes by hydrolysis of organohalosilanes of formula (I) R.sub.a R.sup.1.sub.b SiX.sub.c, wherein R and R.sup.1 identical or different, are an hydrogen atom or a linear or branched C.sub.1 -C.sub.6 alkyl, aryl, alkylaryl or aralkyl group; X is a halogen atom; and a+b+c=4 and 0<c<4; said process comprising the steps of carrying out three or more successive hydrolysis steps (1), (2), (3), in which the reaction medium is capable of exerting an increasing hydrolysing force on the organohalosilanes (I), wherein step (1) is a hydrolysis under pressure in the presence of an aqueous solution S.sub.1 of saturated hydrogen halide, at the pressure and temperature of the reaction medium; and, optionally, carrying out one or more coalescence step (4).

Abstract: Hydroxybenzaldehydes, e.g., vanillin, are prepared by hydrocarbonylating a corresponding halophenol, e.g., 4-bromo-2-methoxyphenol, in the presence of (a) a tertiary amine, (b) a catalyst based on a noble metal, and (c) a phosphine.