[13465-85-5] · Cl3ISi · Trichloroiodosilane · (MW 261.34)
(selective ether-cleaving reagent;1 also cleaves acetals;1,2 mediates reaction of aromatic aldehydes with nitriles to yield secondary amides;3 aromatic aldehydes and acrylonitrile give iminoaldehydes4)
Physical Data: bp 114.5 °C/760 mmHg; mp <-60 °C.
Preparative Methods: prepared through halogen exchange by heating SiCl4 and Sodium Iodide in methylene chloride-acetonitrile or toluene-acetonitrile.1 It also has been prepared by the reaction of SiCl4 and Hydrogen Iodide,5 by heating SiHCl3 with Iodine,5 and by heating silicon with ICl.6
Handling, Storage, and Precautions: Cl3SiI is a moisture-sensitive material; it could be conveniently used in situ. Use in a fume hood.
An important application of Cl3SiI is in regiospecific and selective cleavage of alkyl-alkyl and alkyl-aryl ethers. Primary-secondary alkyl ethers are cleaved to yield primary alkyl iodide and secondary alcohol on workup. This cleavage pattern is opposite to that of boron halides like 9-Bromo-9-borabicyclo[3.3.1]nonane7 and Boron Tribromide,8 which yield secondary bromide and primary alcohol (eq 1). Compared to Iodotrimethylsilane, Cl3SiI shows a greater degree of regiospecificity and slightly faster rate of reaction.1
Selective cleavage of diethers is possible with this reagent (eq 2).
Aromatic aldehydes and nitriles like Acetonitrile or benzonitrile are converted by Cl3SiI to secondary amides, through a redox reaction (eq 3). When Acrylonitrile is used instead, the product is an imino aldehyde (eq 4).
M. Vivekananda Bhatt
Indian Institute of Science, Bangalore, India