Dichlorocarbene
Dichlorocarbene is the reactive intermediate with chemical formula CCl2. Although this material has not been isolated, it is a common intermediate in organic chemistry, being generated from chloroform. This bent diamagnetic molecule rapidly inserts into other bonds.
Preparation
Dichlorocarbene is most commonly generated by reaction of chloroform and a base such as potassium t-butoxide or aqueous sodium hydroxide. A phase transfer catalyst, for instance benzyltriethylammonium bromide, facilitates the migration of the hydroxide in the organic phase.
Other reagents and routes
Another precursor to dichlorocarbene is ethyl trichloracetate. Upon treated with sodium methoxide, it releases CCl2. Phenyl(trichloromethyl)mercury decomposes thermally to also release CCl2:
Dichlorodiazirine, which is stable in the dark, decomposes into dichlorocarbene and nitrogen via photolysis.
Dichlorocarbene can also be obtained by dechlorination of carbon tetrachloride with magnesium with ultrasound chemistry. This method is tolerant to esters and carbonyl compounds because it does not involve strong base.
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