Org. Synth. 1928, 8, 66
DOI: 10.15227/orgsyn.008.0066
Submitted by Roger Adams and F. L. Cohen.
Checked by Henry Gilman and S. A. Harris.
1. Procedure
A solution of 19.5 g. (0.1 mole) of ethyl p-nitrobenzoate (Note 1) in 150 cc. of 95 per cent alcohol is placed in the reaction bottle of the catalytic reduction apparatus (p. 61), and 0.2 g. of platinum oxide catalyst (p. 463) is added. The mixture is shaken with hydrogen until three molecular equivalents have been absorbed. The time required is about seven minutes. The platinum is filtered off and the alcohol removed from the filtrate by distillation. The ethyl p-aminobenzoate, recrystallized from about 40 cc. of ether, melts at 89–90°. The yield is 15–16.5 g. (91–100 per cent of the theoretical amount).
2. Notes
1. The ethyl p-nitrobenzoate should be freed from acid and recrystallized from alcohol until it melts at 57°.
3. Discussion
Ethyl p-aminobenzoate can be prepared by the esterification of p-aminobenzoic acid,1 and by the reduction of ethyl p-nitrobenzoate with ammonium sulfide,2 electrolytically,3 and with tin and alcoholic hydrochloric acid.4 Although the reducing agent used commercially is generally iron and water in the presence of a little acid, the catalytic reduction procedure described is by far the most convenient for the laboratory. The catalytic reduction of ethyl p-nitrobenzoate has been described in the literature.5

References and Notes
  1. Salkowski, Ber. 28, 1921 (1895); Vorländer and Meyer, Ann. 320, 135 (1902); Chemnitius, Pharm. Zentralh. 68, 765 (1927) [C. A. 22, 583 (1928)]; Org. Syn 13, 54.
  2. Limpricht, Ann. 303, 278 (1898).
  3. Alvarez, Mon. farm. therap. 34, 281 (1928) [C. A. 23, 1575 (1929)].
  4. Hill and Cox, J. Am. Chem. Soc. 48, 3218 (1926).
  5. Ferber and Bendix, Ber. 72, 841 (1939).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)


alcohol (64-17-5)

hydrochloric acid (7647-01-0)

ether (60-29-7)

hydrogen (1333-74-0)

iron (7439-89-6)

tin (7440-31-5)

platinum oxide

platinum (7440-06-4)

aminobenzoic acid (118-92-3)

ammonium sulfide

Ethyl p-aminobenzoate (94-09-7)

ethyl p-nitrobenzoate (99-77-4)