CONDENSATION OF o-, m-, AND p- NITROBENZALDE- HYDES WITH MALONIC ACID IN THE PRESENCE OF ORGANIC BASES.

Aldehydes have been condensed with malonic acid using a mixture of pyridine (I mol.) and piperidine (traces) by Haworth, Perkin. and Rankin (J. Chem. Soc.. 1924, 125, 1693) and by Dutt (J. Indian Chem. Soc., 1925, 1, 297) and a few other bases each in molecular proportions (Dalal and Dutt, ibid., 1932. 9, 309). The pyridine-piperidine method, originally given by Haworth, Perkin and Rankin (loc. cit.) and modified by Robinson and Shinoda (J. Chem. Soc., 1924, 1693) has been applied by Chakravarti, Haworth and Perkin, who using m- methoxybenzaldellyde and malonic acid (1 : 3 mols.) in pyridine (3.5 mols.) and a trace of piperi­dine (5 c.c. in 250 c.c. of pyridine with too g. of aldehyde and 160 g. of malonic acid) report "an almost quantitative yield" on heating.

Work in these laboratories has shown that such excessive proportions of the base and of malonic acid are not essential and that these condensations are, as well, even much better carried out, when for one molecule of the aldehyde, only one of the acid and 0.15-0.25 mol. of pyridine or a similar base are used (Kurien and Pandya, J. Indian Chem. Soc., 1934, 11, 824 ; Ali, Kurien and Pandya, Proc. Indian Acad. Sci., 1935, 1A, 440 ; Pandya and Vahidy, ibid., 1935, 2A, 402 ; 1936, 4A, 134, 140, 144 ; 1937, 5A, 437, 181).