Di:substd. benzaldehyde prepn. - by liq. phase oxidn. of corresp. benzyl alcohol using hypohalite and morpholine, pyrrolidine or piperidine deriv.

摘要

Prepn. of substd. benzaldehydes (I) comprises the liq. phase oxidn. of a benzyl alcohol (II) using an inorganic or organic hypochlorite or hypobromite and a morpholine, pyrrolidine or piperidine deriv. (III). R1 = methyl, ethyl, F, Cl or Br; R2 = 1-12C alkyl, or 3-8C cycloalkyl or 6-12C bicycloalkyl opt. mono-, di- or trisubstd. by 1-5C alkyl; Alk=. 1-4C alkyl; Q = =N(+)=OX(-), =N-OH or =N-O; X- = anion; n = 0 or 1; Y = O, CO or =C(R3)(R4); R3, R4 = H, OH or a C- and/or O- organic gp., which can be joined to a 5- or 6- membered ring. Also claimed is the in situ prepn. of cpds. (III) from a corresp. morpholine, pyrrolidine and piperidine and an oxidising agent. Pref. the reaction is carried out in the presence of alkali metal, alkaline earth metal and/or ammonium bromides. The liq. phase is a two-phase aq.-organic system, esp. one in which the aq. phase has a pH or 5-10. USE/ADVANTAGE - Cpds. (I) are intermediates for plant protectants, e.g. pyrethroid derivs. Compared with known processes the new process is industrially applicable, economical and gives cpds. (I) in high yields of up to 85%.