4-(Dimethylamino)benzaldehyde1

[28602-27-9]  · C9H11NO  · 4-(Dimethylamino)benzaldehyde  · (MW 149.19)

(preparation of aldehydes from Grignard reagents;2 color test reagent for pyrroles,3 primary amines,4 and hydrazines5)

Physical Data: mp 74 °C; bp 176-177 °C/17 mmHg.

Form Supplied in: light yellow solid.

Handling, Storage, and Precautions: upon exposure to light, solid will turn pink.

Formylation Reagent.

The reagent reacts with Grignard reagents to give p-dimethylaminophenyl carbinols, which upon treatment with diazonium salts undergo cleavage to the aldehyde (eq 1).2b Use of diazotized sulfanilic acid at pH 5-6 (0-5 °C) as the cleaving agent is advantageous, as the ether-insoluble methyl orange byproduct is readily separated from the aldehyde. Yields for both steps are generally moderate, being 50-75% for the Grignard addition, and 60-82% for the cleavage reaction.2a This method purportedly is advantageous to ethoxymethyleneaniline or ethyl orthoformate in that it provides aldehydes of high purity directly from the ether extracts, and works equally well for the synthesis of aliphatic or aromatic aldehydes (as does the alternative reagent Pentacarbonyliron6).

Related Reagents.

N,N-Dimethylformamide; N-Ethoxymethyleneaniline; N-Methyl-N-(2-pyridyl)formamide.


1. (a) Carnduff, J. QR 1966, 20, 169. (b) Roger, R.; Neilson, D. G. CRV 1961, 61, 179. (c) Kharasch, M. S., Reinmuth, O. Grignard Reactions of Nonmetallic Substances, Prentice Hall: Engelwood Cliffs, NJ, 1954.
2. (a) Stiles, M.; Sisti, A. J. JOC 1960, 25, 1691. (b) Sisti, A.; Burgmaster, J.; Fudim, M. JOC 1962, 27, 279. (c) Sisti, A. J. OSC 1973, 5, 46.
3. Feigl, F. Spot Tests; Elsevier: Amsterdam, 1954; Vol. 2, p 198.
4. Schreiber, J.; Witkop, B. JACS 1964, 86, 2441.
5. Feigl, F. Spot Tests; Elsevier: Amsterdam, 1954; Vol. 2, p 219.
6. Yamashita, M.; Miyoshi, K.; Nakazono, Y.; Suemitsu, R. BCJ 1982, 55, 1663.

Steven J. Brickner

The Upjohn Company, Kalamazoo, MI, USA



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