CH2CHCH2X
CH2CHCH2X, typically written in shorthand as CH2=CH-CH2-X, denotes an allyl halide, a class of organohalides in which a halogen atom X is attached to the terminal carbon of an allyl group. The allyl group is a 3-carbon moiety with a double bond between C1 and C2 and a CH2 substituent at C3, giving the general formula C3H5X with X = Cl, Br, or I. Allyl halides are widely used as reactive intermediates in organic synthesis because the allylic position is activated toward nucleophilic attack and rearrangement.
Structure and nomenclature: The halogen is bonded to the primary allylic carbon, while the adjacent C=C bond
Preparation: Allyl halides are typically prepared by converting allyl alcohols or related derivatives with reagents such
Reactions and applications: Allyl halides participate in a variety of transformations. They undergo SN2 substitutions at
Safety: Allyl halides are typically lachrymatory and corrosive; they should be handled with appropriate PPE and
See also: allyl group, allylation, vinyl halide, propenyl derivatives.