Copper Chromite-Quinoline

[12053-18-8]  · Cr2Cu2O5  · Copper Chromite-Quinoline  · (MW 311.07)

[91-22-5]  · C9H7N  · Copper Chromite-Quinoline  · (MW 129.16)

(decarboxylation catalyst)

Physical Data: see the entries for Copper Chromite and Quinoline.

Form Supplied in: both components are widely available. The frequently-used barium-promoted copper chromite contains varying amounts (ca. 10%) of BaO.

Preparative Methods: see the entries for the individual components.

Handling, Storage, and Precautions: the copper chromite catalyst is air- and moisture-stable; however, it should be kept as dry as possible to avoid spattering at elevated temperatures. Both reagents are toxic irritants and should be handled in a well-ventilated fume hood.

Copper Chromite (chromium copper oxide) has long been used, both industrially and in the academic laboratory, as a catalyst for hydrogenation and other reductions, but has been supplanted in recent years by the development of hydrides and other reducing agents.

Decarboxylation.

Quinoline is a favorable solvent for the decarboxylation of unsaturated carboxylic acids with Copper powder, Cu2Cr2O5, and similar catalysts, as it forms the requisite carboxylate anion while providing a relatively low-boiling reaction medium;1a-b most reactions are performed at reflux between 170-200 °C. Both anhydrous Cu2Cr2O5 and its barium-promoted forms effect decarboxylations, although metal oxide (e.g. BaO) content tends to increase reaction rates. Thus (E)-a-phenylcinnamic acid is decarboxylated in high yield to cis-stilbene in 10 min (eq 1).1b

Decarboxylation of 4-acyl-2-pyrrolecarboxylic acids, which gives low yields of 3-acylpyrrole products when ethanolamine and 2,6-lutidine are employed as solvents, is effected at 180-200 °C in much improved (76-85%) yields, with minimal tarring, when quinoline is used (eq 2).2

In a synthesis of benzo[a]cycl[3.2.2]azine, decarboxylation of the intermediate diacid (eq 3) gave the desired product in 49% yield.3 Similar reactions with benzoic acid (eq 4) and acylfuran (eq 5) derivatives have been reported.4,5


1. (a) FF 1967, 1, 156, 975. (b) Fieser, L. F.; Williamson, K. L. Organic Experiments, 7th ed.; Heath: Lexington, MA, 1992; p 493. (c) Buckles, R. E.; Wheeler, N. G. OSC 1963, 4, 857.
2. Anderson, H. J.; Clase, J. A.; Loader, C. E. SC 1987, 17, 401.
3. Tominaga, Y.; Shiroshita, Y.; Gatou, H.; Matsuda, Y. H 1986, 24, 3071.
4. Agurell, S.; Granelli, I.; Leander, K.; Rosenblum, J. ACS 1974, B28, 1175.
5. Moursounidis, J.; Wege, D. TL 1986, 27, 3045.

Edward J. Parish & Stephen Kizito

Auburn University, AL, USA



Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.