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Acyl halides are rather reactive compounds often synthesized to be used as intermediates in the synthesis of other organic compounds. For example, an acyl halide can react with: water, to form a carboxylic acid. This hydrolysis is the most heavily exploited reaction for acyl halides as it occurs in the industrial synthesis of acetic acid.
A general acyl group (blue) in a ketone (top left), as an acylium cation (top centre), as an acyl radical (top right), an aldehyde (bottom left), ester (bottom centre) or amide (bottom right). ( R 1 , R 2 and R 3 stands for organyl substituent or hydrogen in the case of R 1 )
Acyl halides and acid anhydrides of carboxylic acids are also common acylating agents. In some cases, active esters exhibit comparable reactivity. All react with amines to form amides and with alcohols to form esters by nucleophilic acyl substitution. Acylation can be used to prevent rearrangement reactions that would normally occur in alkylation.
Acid halides are the most reactive acyl derivatives, and can easily be converted into any of the others. Acid halides will react with carboxylic acids to form anhydrides. If the structure of the acid and the acid chloride are different, the product is a mixed anhydride.
Here, a strong Lewis acid is required to generate either a carbocation from an alkyl halide in the Friedel-Crafts alkylation reaction or an acylium ion from an acyl halide. In the vast majority of cases, reactions that involve leaving group activation generate a cation in a separate step, before either nucleophilic attack or elimination.
Also, there are no carbocation rearrangements, as the acylium ion is stabilized by a resonance structure in which the positive charge is on the oxygen. The viability of the Friedel–Crafts acylation depends on the stability of the acyl chloride reagent. Formyl chloride, for example, is too unstable to be isolated.
The Corey–Seebach reaction is of interest as an acyl anion equivalent, allowing aldehydes to be converted to ketones. The lithiated 1,3-dithiane can be alkylated with alkyl halides , epoxides , [ 3 ] [ 4 ] ketones , acyl halides , and iminium salts, which after hydrolysis of dithioacetals can yield ketones, β-hydroxyketones, α ...
N-acyl amides are a general class of endogenous fatty acid compounds characterized by a fatty acyl group linked to a primary amine metabolite by an amide bond. Broadly speaking, N-acyl amides fall into several categories: amino acid conjugates (e.g., N-arachidonoyl-glycine), neurotransmitter conjugates (e.g., N-arachidonoyl-serotonin), ethanolamine conjugates (e.g., anandamide), and taurine ...