[638-73-3]  · CHClI2  · Chlorodiiodomethane  · (MW 302.27)

(carbenoid precursor used for formation of halo substituted cyclopropanes2)

Physical Data: clear liquid, bp 200 °C (88 °C/30 mmHg);3 d 3.17 g cm-3 at 0 °C.4

Solubility: sol CH2Cl2, benzene, hexane, dioxane, chloroform; insol water.

Preparative Methods: reaction of Iodoform with Mercury(II) Chloride;5 reaction of Chloroform with Ethyl Iodide in the presence of Aluminum Chloride;2 reaction of chloroform with Sodium Iodide and Sodium Hydroxide under phase transfer catalysis.6 Drying: material is redistilled before use.

Analysis of Reagent Purity: bp and NMR (d 1H 6.18 ppm;6 d 13C (calc. 60.6 ppm)).7

Handling, Storage, and Precautions: best kept in the dark for extended periods.

Halosubstituted Cyclopropanes.

Reaction of chlorodiiodomethane with alkenes under a variety of conditions gives rise to substituted cyclopropanes in reasonable yield. The additions, which have been proven to be electrophilic in nature, give product mixtures which are dependent on the conditions used. If hydroxide is used, under phase transfer conditions, chloroiodocyclopropanes result (eq 1). A wide range of alkene substituents has been studied.8

Reaction with alkenes in the presence of Diethylzinc, however, gives rise to chloro-substituted cyclopropanes almost exclusively (eq 2).9,10 The high endo:exo ratio is of note here (the analogous reaction with bromodiiodomethane gives the bromocyclopropane with a 2.8:1 endo:exo ratio).

The most widely studied additions to alkenes are those using copper metal to generate the carbenoid species. Exclusive formation of chlorocyclopropanes ensues and the yields are often good. Addition to cyclohexene in the presence of Copper powder gives a 48% yield of product, but with a diminished endo:exo ratio (eq 2).10 A similar addition to cis-cyclooctene gives a 50% yield of product with a 6.2:1 endo:exo ratio.2 Application of this protocol to other alkenes was reported (eq 3).2 The high cis,cis:trans,trans ratio for addition to (Z)-4-octene is complemented by the exclusive formation of the cis,trans adduct with (E)-4-octene. Addition to substituted styrenes has been studied in order to probe the electrophilic nature of the addition reaction (eq 4).2 While the cis:trans ratios of the product cyclopropanes remained comparable, the rates of formation varied widely, allowing a Hammet ρ value of -1.13 for this reaction to be assigned. The relative stability of chlorodiiodomethane and related halomethanes to hydrolysis has been studied.11

Experiments conducted in the presence of radical inhibitors gave the most reproducible results for base hydrolysis in aqueous (dioxane/water) solution, exposing this potential source of side reaction.11

Related Reagents.

Bis(trichloromethyl)mercury; Bromoform; Chlorodifluoromethane; Chloroform; Chloroiodomethane; Phenyl(tribromomethyl)mercury; Phenyl(trichloromethyl)mercury.

1. Doyle, M. P. ACR 1986, 19, 348; Doyle, M. P. CR 1986, 86, 919; Krief, A. T 1980, 36, 2531; FF 1975, 5, 27; 1979, 7, 74.
2. Kawabata, N.; Tanimoto, M.; Fujiwara, S. T 1979, 35, 1919.
3. Kudchadker, A. P.; Kudchadker, S. A.; Shukla, R. P.; Patnaik, P. R. J. Phys. Chem. Ref. Data 1979, 8, 499.
4. Kudchadker, A. P.; Kudchadker, S. A.; Patnaik, P. R.; Mishra, P. P. J. Phys. Chem. Ref. Data 1978, 7, 425.
5. Auger, V. CR 1908, 146, 1037.
6. Dehmlow, E. V.; Stutten, J. LA 1989, 187.
7. Somayajulu, G. R.; Kennedy, J. R.; Vickrey, T. M.; Zwolinski, B. J. JMR 1979, 33, 559.
8. Mathias, R.; Weyerstahl, P. AG(E) 1974, 13, 132.
9. Nishimura, J.; Furukawa, J. CC 1971, 1375.
10. Kawabata, N.; Naka, M.; Yamashita, S. JACS 1976, 98, 2676.
11. Hine, J.; Ehrenson, S. J. JACS 1958, 80, 824.

Graham B. Jones & Brant J. Chapman

Clemson University, SC, USA

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