Abstract: A process for preparing substituted aromatic and heteroaromatic aldehydes or carboxylic acids of the formula in which R1 and R2 are H, C1-C4 alkyl, C1-C4 alkoxy, OH, NO2, CN, COOH, CONH2, COOR, NH2, SO3H or halogen and R is C1-C4 alkyl and where R1 and R2 are not simultaneously H, X is C or N and Z is CHO or COOH, from the corresponding symmetric stilbene compounds of the formula in which R1, R2 and X are as defined above, by aqueous ozonolysis and subsequent isolation of an aldehyde or oxidation to give the corresponding carboxylic acid.

Abstract: Process for the preparation of aliphatic or aromatic mono- or dicarboxylic acids of 4 to 22 carbon atoms by oxidation of the corresponding aldehydes having the same number of carbon atoms in a carboxylic acid from the group consisting of formic acid, acetic acid, and propionic acid or in a carboxylic acid/water mixture at a temperature of 50.degree.-130.degree. C. and at 1 to 25 bar and in the presence of an oxidizing agent.

Abstract: Process for the preparation of alpha, omega-alkanedicarboxylic acids of the general formula I ##STR1## in which A is an alkylene radical having 4-14 C atoms by reacting a cycloalkene of the general formula II ##STR2## in which A has the abovementioned meaning with ozone in the presence of an inert solvent, catalytically hydrogenating the peroxide solution formed, followed by oxidation of the dialdehyde formed to the diacid of the formula I in the presence of an inert aprotic solvent.