Di:fluoro-methoxy aromatic aldehyde prodn. - from corresp. hydroxy aldehyde and di:fluoro-chloro-methane, useful intermediates for dyes, pesticides etc.

摘要

Prodn of the difluoromethoxy cpds of formula (I) (where n is 1 or 2) comprises reacting the appropriate mono- or di-hydroxy aldehyde (II) with difluorochloromethane in an aq dioxan medium at 60-70 deg C, in presence of 6-10 moles caustic alkali per mole (II). Opt reaction is also in the presence of 0.3- 0.4 moles Na hydrosulphite dihydrate per mole (II). (I) are intermediates for physiologically active cpds., dyes and pesticides. This method is simpler than known processes and gives higher yields. Redox disproportionation (Cannizzaro reaction) is minimised and addn of the hydrosulphite inhibits reaction of (I) and (II) with difluorocarbene formed as an intermediate.