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An acyl halide (also known as an acid halide) is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group. If the acid is a carboxylic acid, the compound contains a –COX functional group, which consists of a carbonyl group singly bonded to a halogen atom. The general formula for such an acyl halide can be written RCOX, where R may be, for example, an alkyl group, CO is the carbonyl group, and X represents the halide, such as chloride. Acyl chlorides are the most commonly encountered acyl halides, but acetyl iodide is the one produced (transiently) on the largest scale. Billions of kilograms are generated annually in the production of acetic acid.〔Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic Acid" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 〕 The hydroxyl group of a sulfonic acid may also be replaced by a halogen to produce the corresponding sulfonyl halide. In practical terms this is almost always chloride to give the sulfonyl chloride. == Preparation == A common laboratory method for the synthesis of acyl halides entails reaction of carboxylic acids with reagents such as thionyl chloride or phosphorus pentachloride for acyl chlorides, phosphorus pentabromide for acyl bromides and cyanuric fluoride for acyl fluorides. Aromatic acyl chlorides can be prepared by chloroformylation, a specific type of Friedel-Crafts acylation using formaldehyde as the reagent. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Acyl halide」の詳細全文を読む スポンサード リンク
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