PROCESS FOR THE PREPARATION OF HYDROXY BENZENE CARBOXALDEHYDES

摘要

A process is provided for the preparation of hydroxy benzene carboxaldehydes having the formula: wherein: R is selected from the group consisting of alkyl, alkoxy, cycloalkyl, aryl alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxyalkyl having at least two to about twenty carbon atoms; hydroxy; aldehyde CHO; and halogen; n1 n2 and n3 are zero or 1; and at least one of n1, n2 and n3, is 1; and x is zero, 1, 2, 3 or 4, which comprises: (1) condensing with a formaldehyde compound a phenol having the formula: wherein R is selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, cycloalkyl, aryl, alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxy; and halogen; and x is zero, 1, 2, 3 or 4, and unsubstituted in at least one ortho or para position in an aqueous reaction medium comprising phenol:HCHO in a molar ratio within the range from about 1:0.1 to about 1:3 and alkali in a molar ratio alkali:phenol within the range from about 1:0.1 to about 1:2 and an alkali concentration not exceeding 30% by weight at a temperature within the range from about 0 to about 120.degree.C and obtaining a reaction mixture comprising a mixture of monomethylol and polymethylol phenols having the formula: wherein R is selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, cycloalkyl, aryl, alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxy; and halogen; n1, n2 and n3, are zero or 1; and at least one of n1, n2 and n3, is 1; and x is zero, 1, 2, 3 or 4; (2) subjecting the reaction mixture without separation of the monomethylol species from polymetholol species to oxidation under conditions favoring oxidation of methylol species to the corresponding aldehyde species in the presence of oxygen and an amount of alkali that is at least stoichiometrically equal to the amount of phenol and a platinum or palladium oxidation catalyst, preferably but optionally with a promoter selected from the group consisting of bismuth, lead, silver, tellurium, cadmium, and tin in the form of the metal and/or compounds thereof at a temperature within the range from about 0.degree. to about 100.degree.C and a pH within the range from about 11 to about 13.5; and then (3) separating and recovering the desired aldehyde in the reaction mixture. A process also is provided for selectively decarbonylating any undesired aldehyde species to remove all or selected aldehyde groups in certain ring positions, either to yield more desirable aldehyde species or for recycling as starting material.