Org. Synth. 1930, 10, 10
DOI: 10.15227/orgsyn.010.0010
Submitted by Arthur Lachman
Checked by C. R. Noller
1. Procedure
A mixture of 100 g. (0.55 mole) of benzophenone (Org. Syn. Coll. Vol. I, 1941, 95), 60 g. (0.86 mole) of hydroxylamine hydrochloride (Org. Syn. Coll. Vol. I, 1941, 318), 200 cc. of 95 per cent ethyl alcohol, and 40 cc. of water is placed in a 2-l. round-bottomed flask. To this is added in portions, with shaking, 110 g. (2.75 moles) of powdered sodium hydroxide. If the reaction becomes too vigorous, cooling with tap water may be necessary. After all the sodium hydroxide has been added, the flask is connected to a reflux condenser, heated to boiling, and refluxed for five minutes. After cooling, the contents are poured into a solution of 300 cc. of concentrated hydrochloric acid in 2 l. of water. The precipitate is filtered with suction, thoroughly washed with water, and dried (Note 1). The yield is 106–107 g. (98–99 per cent of the theoretical amount) of a product melting at 141–142°. On crystallizing 20 g. from 80 cc. of methyl alcohol, 13 g. of crystalline material of the same melting point is obtained (Note 2).
2. Notes
1. This crude material dried overnight at about 40° is practically pure and if used at once is satisfactory for the preparation of diphenylmethane imine hydrochloride (p. 234).
2. In the presence of oxygen and traces of moisture, benzophenone oxime is gradually converted into a mixture of benzophenone and nitric acid.1 A good method of preserving this oxime is to dry it in a vacuum desiccator, fill the desiccator with pure carbon dioxide, re-evacuate, and fill again with carbon dioxide. The preparation may then be transferred to a bottle, also filled with carbon dioxide, and sealed against access of air.
3. Discussion
Benzophenone oxime has been prepared in quantity by treating an aqueous alcoholic mixture of benzophenone and hydroxylamine hydrochloride with hydrochloric acid,2 with sodium carbonate,3 with alcoholic potassium hydroxide,4 or with aqueous sodium hydroxide.5 It has also been obtained by treating bisnitrosylbenzohydryl with alcoholic potassium hydroxide,6 and by the oxidation of α-aminodiphenylmethane with magnesium persulfate solution.7
This preparation is referenced from:

References and Notes
  1. Hollemann, Rec. trav. chim. 13, 429 (1894); Lachman, J. Am. Chem. Soc. 46, 1478 (1924).
  2. Beckmann, Ber. 19, 989 (1886).
  3. Janny, ibid. 15, 2782 (1882).
  4. Derick and Bornmann, J. Am. Chem. Soc. 35, 1287 (1913).
  5. Lachman, ibid. 46, 1481 (1924); 47, 262 (1925).
  6. Behrend and Platner, Ann. 278, 369 (1894).
  7. Bamberger and Seligman, Ber. 36, 704 (1903).

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


ethyl alcohol (64-17-5)

hydrochloric acid (7647-01-0)

methyl alcohol (67-56-1)

sodium hydroxide (1310-73-2)

nitric acid (7697-37-2)

sodium carbonate (497-19-8)

oxygen (7782-44-7)

carbon dioxide (124-38-9)

potassium hydroxide (1310-58-3)

Benzophenone (119-61-9)

Hydroxylamine hydrochloride (5470-11-1)

Benzophenone oxime (574-66-3)

diphenylmethane imine hydrochloride (5319-67-5)

α-aminodiphenylmethane (91-00-9)

magnesium persulfate