Chloramine-Aluminum(III) Chloride

NH2Cl-AlCl3
(NH2Cl)

[10599-90-3]  · ClH2N  · Chloramine-Aluminum(III) Chloride  · (MW 51.48) (AlCl3)

[7446-70-0]  · AlCl3  · Chloramine-Aluminum(III) Chloride  · (MW 133.34)

(reagent for aminating arenes, alkanes, and alkyl chlorides1)

Physical Data: bp -66 °C.

Solubility: sol cold H2O, ether, and methylene chloride; v sl sol CCl4 and benzene.

Analysis of Reagent Purity: chlorine in chloramine is determined by iodometric titration.8

Preparative Methods: Chloramine can be prepared either by a gas phase or a liquid phase technique. In the gas phase technique, ammonia and chlorine are allowed to react and chloramine is collected in methylene chloride.1-4 Since the gas phase technique is relatively cumbersome and provides only small amounts of the desired material, liquid phase techniques in which chloramine is extracted into an organic solvent from an aqueous phase are used. Sodium hypochlorite solution is added to aqueous ammonia at 0 °C; chloramine is distilled with water into cold ether5-7 or extracted with methylene chloride.1

Handling, Storage, and Precautions: this reagent should be handled in a fume hood.

Amination.

Mono-, di-, and trichloramines in the presence of Aluminum Chloride have been reported to aminate various organic substrates, e.g. arenes, alkanes, and alkyl halides. Amination is carried out with an excess of the aromatic compound, a 1.7-2 molar ratio of AlCl3/N-haloamine, and an aryl halide additive in the case of dichloramine at temperatures in the range -35 to -15 °C. Under these conditions the reaction of toluene with chloramine/AlCl3 gives primarily o- and p-chlorotoluene, and only 13% of m-toluidine (eq 1).

The reactions with trichloramine-aluminum(III) chloride and dichloramine/AlCl3 give m-toluidine in 43%1,9 and 25%10 yields, respectively. Based on literature analogy involving the trichloramine/AlCl3 system, a mechanistic scheme entailing addition-elimination is proposed for the meta substitution (eq 2).

Amination of adamantane with chloramine/AlCl3 gives 1-aminoadamantane (eq 3) in 40% yield, again in lower yield than that obtained with trichloramine/AlCl3 (85% yield).1,11,12

Amination of t-butyl chloride produces t-butylamine (eq 4) in 7-20% yield, which is much lower than that obtained with trichloramine/AlCl3 (56% yield).1,13

A possible rationalization for the lower yields with chloramine as compared to trichloramine in amination of the three organic substrates has been given.1


1. Strand, J. W.; Kovacic, P. JACS 1973, 95, 2977.
2. Gilson, I. T.; Sisler, H. H. IC 1965, 4, 273.
3. Sisler, H. H.; Omietanski, G. M. Inorg. Synth. 1957, 5, 91.
4. Theilacker, W.; Wagner, E. In Newer Methods of Preparative Organic Chemistry, Foerst, W. Ed.; Academic: New York, 1964; Vol. 3, p 309.
5. Coleman, G. H.; Johnson, H. L. Inorg. Synth. 1939, 1, 59.
6. Coleman, G. H.; Forrester, R. A. JACS 1936, 58, 27.
7. Coleman, G. H.; Hauser, C. R. JACS 1928, 50, 1193.
8. Kovacic, P.; Chaudhary, S. S. OS 1968, 48, 4.
9. Kovacic, P; Goralski, C. T.; Hiller, J. J.; Levisky, J. A.; Lange, R. M. JACS, 1965, 87, 1262.
10. Kovacic, P.; Lange, R. M.; Foote, J. L.; Goralski, C. T.; Hiller, J. J.; Levisky, J. S. JACS 1964, 86, 1650.
11. Kovacic, P.; Roskos, P. D. TL 1968, 56, 5833.
12. Kovacic, P.; Roskos, P. D. JACS 1969, 91, 6457.
13. Kovacic, P.; Lowery, M. K. JOC 1969, 34, 911.

Ender Erdik

Ankara University, Turkey



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