[5314-83-0]  · C4H10BCl  · Chlorodiethylborane  · (MW 104.39)

(reagent for the synthesis of organoboranes;1 protection of sugars;2 cleavage of strained ethers;3 component of polymerization catalysts4)

Physical Data: bp 81 °C.

Solubility: sol diethyl ether, THF, pentane, benzene.

Preparative Methods: chlorodiethylborane is conveniently prepared by the redistribution reaction of triethylborane and boron trichloride in the presence of a catalytic amount of tetraethyldiborane.5 The product is isolated by distillation in 98% yield. Other methods are also known,6-8 e.g. 10B-labelled chlorodiethylborane is obtained by the reaction of 10B-labelled triethylborane with antimony pentachloride.6

Handling, Storage, and Precautions: chlorodiethylborane is a colorless, mobile, thermally stable liquid. It is spontaneously flammable in air and should be handled and stored under nitrogen or argon. It reacts with alcohols and water.


Various diethylorganoboranes containing alkyl,9 alkenyl,10 alkynyl,11 allylic,12-16 aryl,17,18 amino,19-24 and other groups25-30 are prepared by the transmetalation reaction of chlorodiethylborane with the corresponding alkali metal, tin, silver, or silicon derivatives. Allylic diethylboranes generated from alkenes via metalation are useful intermediates in the contrathermodynamic isomerization and allylic monodeuteration of alkenes (eq 1),12,14 and the hydroxyalkylation, hydroxymethylation, acylation, and formylation of alkenes (eqs 2 and 3).13,15,16

Bis(dialkylboryl)alkenes derived from l-alkynes are readily hydrolyzed to stereochemically pure (Z)-alkenes (eq 4).10

The reduction of chlorodiethylborane with Lithium Aluminum Hydride affords tetraethyldiborane, a useful hydroborating agent, also available by other methods.31-33 This method, however, initially generates a pure reagent. Deuterium labelled tetraethyldiborane is readily prepared (eq 5).31

Tetraethyldiborane and other primary alkylboranes exist in equilibrium with alkyldiboranes and trialkylboranes. The mixtures have a mean composition corresponding to tetraalkyldiborane.33

The hydroxyl and carboxyl groups of sugars can be protected as diethylboryl derivatives with a mixture of chlorodiethylborane and triethylborane (eq 6).2

Cleavage of Ethers.34

Chlorodiethylborane cleaves strained cyclic ethers, e.g. oxetanes.3 Dialkylbromoboranes, particularly B-bromo-9-borabicyclo[3.3.1]nonane, are more effective reagents.35

Polymerization Catalysis.

Chlorodiethylborane is applied in polymerization catalysis, e.g. regulating the alternation of copolymerization of methacrylate and styrene,4,36,37 or as a component in Ziegler-Natta-type catalysts for polymerization of alkenes.

Related Reagents.

9-Bromo-9-borabicyclo[3.3.1]nonane; Bromodimethylborane.

1. Köster, R. MOC 1982-1984, XIII/3a-c.
2. Köster, R.; Idelmann, P.; Dalhoff, W. V. S 1982, 650.
3. Köster, R. MOC 1982, XIII/3a, 546.
4. Hirai, H.; Takeuchi, K.; Komiyama, M. J. Polym. Sci., Polym. Chem. Ed. 1985, 23, 901.
5. Köster, R.; Binger, P. Inorg. Synth. 1974, 15, 149.
6. Köster, R.; Bellut, H.; Benedikt, G.; Ziegler, E. LA 1969, 724, 34.
7. Nöth, H.; Storch, W. Synth. React. Inorg. Metal-Org. Chem. 1971, 1, 197.
8. Arase, A.; Hoshi, M.; Masuda, Y. BCJ 1981, 54, 299.
9. Köster, R.; Benedikt, G.; Grassberger, M. A. LA 1968, 719, 187.
10. Binger, P.; Köster, R. TL 1965, 1901.
11. Köster, R.; Horstschäfer, H.-J.; Binger, P. LA 1968, 717, 1.
12. Zaidlewicz, M. JOM 1985, 293, 139.
13. Zaidlewicz, M. TL 1986, 27, 5135.
14. Zaidlewicz, M.; Panda, C. S. S 1987, 645.
15. Zaidlewicz, M. S 1988, 701.
16. Zaidlewicz, M. JOM 1991, 409, 103.
17. Köster, R.; Benedikt, G.; Fenzl, W.; Reinert, K. LA 1967, 702, 197.
18. Wrackmeyer, B.; Nöth, H. CB 1976, 109, 1075.
19. Nöth, H.; Otto, P.; Storch, W. CB 1986, 119, 2517.
20. Nöth, H.; Prigge, H.; Rotsch, A. R. CB 1986, 119, 1361.
21. Nöth, H.; Storch, W. CB 1984, 117, 2140.
22. Nöth, H.; Storch, W. CB 1977, 110, 2607.
23. Nöth, H.; Reiner, D.; Storch, W. CB 1973, 106, 1508.
24. Paetzold, P.; Bennigsen-Mackiewicz, T. CB 1981, 114, 298.
25. Niedenzu, K.; Woodrum, K. R. IC 1989, 28, 4022.
26. Edwin, J.; Böhm, M. C.; Chester, N.; Hoffman, D. M.; Hoffmann, R.; Pritzkow, H.; Siebert, W.; Strumpf, K.; Wadepohl, H. OM 1983, 2, 1666.
27. Ioffe, S. L.; Kalinin, A. V.; Golovina, T. N.; Khasanov, B. N.; Tartakovskii, V. A. IZV 1978, 942.
28. Ioffe, S. L.; Shaskov, A. S.; Blyumenfel'd, A. L.; Leont'eva, L. M.; Makarenkova, L. M.; Belkina, O. B.; Tartakovskii, V. A. IZV 1976, 2547.
29. Shitov, O. P.; Leont'eva, L. M.; Ioffe, S. L.; Khasapov, B. N.; Novikov, V. M.; Stepanyants, A. U.; Tartakovskii, V. A. IZV 1974, 2782.
30. Ioffe, S. L.; Leont'eva, L. M.; Blyumenfel'd, A. L.; Shitov, O. P.; Tartakovskii, V. A. IZV 1974, 1659.
31. Köster, R.; Griasnow, G.; Larbig, W.; Binger, P. LA 1964, 672, 1.
32. Köster, R.; Bruno, G.; Binger, P LA 1961, 644, 1.
33. Köster, R.; Binger, P. Inorg. Synth. 1974, 15, 141.
34. Bhatt, M. V.; Kulkarni, S. U. S 1983, 249.
35. Bhatt, M. V. JOM 1978, 156, 221.
36. Hirai, H.; Takeuchi, K.; Komiyama, M. J. Polym. Sci., Polym. Chem. Ed. 1981, 19, 2581.
37. Hirai, H.; Takeuchi, K. Macromol. Chem. Rapid Commun. 1980, 1, 541.

Marek Zaidlewicz

Nicolaus Copernicus University, Torun, Poland

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