酰基化Acylation

AlCl₃ 与酰氯生成酰基正离子（被共振稳定，不重排），对芳环进行亲电取代得芳基酮。产物酮的羰基使环钝化并与 AlCl₃ 络合，所以不发生多次酰基化，但需化学计量的 AlCl₃。与克莱门森或沃尔夫–基斯纳还原联用可得直链烷基苯。

AlCl₃ and an acyl chloride form a resonance-stabilised acylium ion (no rearrangement) that substitutes the arene to give an aryl ketone. The ketone deactivates the ring and complexes AlCl₃, so polyacylation does not occur but stoichiometric AlCl₃ is required. Followed by Clemmensen or Wolff–Kishner reduction it gives straight-chain alkylbenzenes.

胺与酰氯（肖滕–鲍曼条件，水相碱）或酸酐快速成酰胺；醇的酰化常用酸酐/吡啶或 DMAP 催化。乙酰化用于保护氨基、羟基；乙酰水杨酸（阿司匹林）由水杨酸 O-乙酰化制得。

Amines react rapidly with acyl chlorides (Schotten–Baumann, aqueous base) or anhydrides to give amides; alcohols are acylated with anhydride/pyridine or DMAP catalysis. Acetylation protects amines and alcohols; aspirin is made by O-acetylation of salicylic acid.

组蛋白乙酰化调节染色质结构和基因表达；蛋白质 N 端乙酰化、脂酰化（棕榈酰化）影响蛋白定位与功能。乙酰辅酶 A 是体内主要乙酰基供体。

Histone acetylation regulates chromatin and gene expression; N-terminal acetylation and lipidation (palmitoylation) affect protein localisation. Acetyl-CoA is the main biological acetyl donor.