THE CONDENSATION OF VANILLIN AND PIPER- 

 ONAL WITH CERTAIN AROMATIC AMINES* 



BY ALVIN S. WHEELER 



In extension of the work done in this laboratory upon the con- 

 densation of chloral with aromatic amines,f we have carried out 

 the condensation of the aldehydes, vanillin and piperonal, with 

 p-aminobenzoic acid, its ethyl ester, and also with p-anisidine. 

 Pawlewskiij: has described the product obtained by the condensa- 

 tion of anthranilic acid with vanillin, stating it to be an amor- 

 phous substance. We find that the para acid yields with vanillin 

 a crystallin product with a melting point 40° higher. The con- 

 densation of anthranilic acid with j)iperonal was carried out by 

 H. Wolf.§. Our product with the para acid melts 44° higher. 

 The products with the ethyl ester have very much lower melting 

 points. The work with the ester was undertaken with the hope 

 of discovering more cases of isomerism, a few cases having 

 already been observed in similar reactions. No indications of 

 isomerism, however, were noted in handling the two ester de- 

 rivatives. 



The condensations take place readily in a boiling solvent with 

 the loss of one molecule of water, one molecule of each con- 

 stituent taking part in the reaction. By working at low tem- 

 peratures it is sometimes possible to bring two molecules of the 

 amine into combination with one of the aldehyde. In the re- 

 action between the free para acid and piperonal a small quantity 

 of a low melting substance, m. 171 — 3°, was isolated and the 

 amount was greatly increased by using two molecules of the acid. 

 Notwithstanding many analyses, no satisfactory figures could 

 be obtained for a dibenzylidene derivative. 



The condensation product of /)-aminobenzoic acid with va- 

 nillin is unique among the benzylidene derivatives in that it is 

 the only one that takes up a molecule of water of crystallization. 

 Exposed to a moist atmosphere it gradually assumes a reddish 



* Reprinted from the Journal of the American Chemical Society, Vol. XXXV. 

 No. 8. August, mi.''.. 



t Wheeler and Weller, Thls .Tocrxal, 24, 1063 (1902). Wheeler, ibid., 30, 136 

 (1908). Wheeler and .Tordan, Ihid., 31, 937 (1909). 



t Ber., 37, 596 (1904). 



§ Monatsh., 31, 903. 77 



