SYNTHESIS AND CHARACTERIZATION OF HYDROBENZOIC ACID FORMALDEHYDE POLYMERS

Salicylic acid is a bifunctional monomer with one reaction site para to the OH group and other reaction site ortho to the OH group. If nay one of these positions in salicylic acid is occupied by a substituent, such an acid will cease to be a monomer for the phenol-formaldehyde type condensation. It is for this reason that 5-amino and 5-chloro salicylic acid are not able to participate in the reaction under consideration. However if substituent is para to the COOH group, the so-substituted salicylic acid can, in participate would function as a monomer. The condensations of 4-amino salicylic acid (PAS) with formaldehyde have been reported [21]. As compared to phenol, salicylic acid would be less reactive in the phenol-formaldehyde type reaction due to deactivating effect of COOH group and also due to statistical disadvantage three reaction sites being reduced to two.