FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to a method of synthesis of derivatives of 3-carboxy-4- hydroxybenzaldehydes from phenolic compounds carrying formyl and/or hydroxymethyl groups at positions 2 and 4. Invention describes also synthesis of 4-hydroxy-benzaldehyde from 3-carboxy-4- hydroxybenzaldehyde and synthesis of 3-methoxy-4-hydroxybenzaldehyde and 3-ethoxy-4-hydroxybenz- aldehyde named as "vanillin" and "ethylvanillin", respectively. Method of synthesis of 3-carboxy-4- hydroxybenzaldehyde is carried out by selective oxidation of phenolic compound comprising formyl group and/or hydroxymethyl group at position 2 or 4 being the group at position 2 is oxidized to carboxyl group and hydroxymethyl group at position 4 is oxidized to formyl group if necessary. Decarboxylation of 3-carboxy-4- hydroxybenzaldehyde results to formation of 4-hydroxy-benzaldehyde. EFFECT: improved methods of synthesis. 26 cl, 13 ex
