定义Definition
贝克曼重排是酮肟在酸（浓硫酸、多聚磷酸、PCl₅ 等）作用下重排为 N-取代酰胺的反应；环酮肟重排为内酰胺。
The Beckmann rearrangement converts a ketoxime with acid (concentrated H₂SO₄, polyphosphoric acid, PCl₅, etc.) into an N-substituted amide; cyclic ketoximes give lactams.
机理与立体专一性Mechanism and stereospecificity
肟羟基被质子化（或酯化）成好的离去基团；与离去基团处于反式的那个碳基团带着电子对迁移到氮上，同时 N–O 键断裂，生成腈鎓离子；水进攻后互变异构为酰胺。迁移基团由肟的 E/Z 构型决定（反式迁移）。
The oxime OH is protonated (or esterified) into a leaving group; the group anti to it migrates to nitrogen as N–O breaks, forming a nitrilium ion that water attacks and that tautomerises to the amide. Which group migrates is set by oxime geometry (anti migration).
由来Origin
德国化学家恩斯特·奥托·贝克曼于 1886 年报道。
Reported by the German chemist Ernst Otto Beckmann in 1886.
工业意义Industrial importance
环己酮肟在发烟硫酸中重排得 ε-己内酰胺，开环聚合即尼龙-6，全球年产数百万吨。现代工艺还发展了以分子筛为催化剂的气相贝克曼重排，减少硫酸铵副产物。
Cyclohexanone oxime rearranges in oleum to ε-caprolactam, whose ring-opening polymerisation gives nylon-6 — millions of tonnes a year. Vapour-phase processes over zeolites reduce the ammonium-sulfate by-product.
反应Reactions
浓硫酸、发烟硫酸、多聚磷酸或 PCl₅、TsCl/吡啶；加热
Concentrated or fuming H₂SO₄, polyphosphoric acid, PCl₅ or TsCl/pyridine, with heating
肟羟基活化为离去基团。
Activation of the oxime OH.
反式基团迁移到氮，N–O 断裂，生成腈鎓离子。
Anti group migrates to N with N–O cleavage, giving a nitrilium ion.
水加成、互变异构得酰胺。
Water addition and tautomerisation give the amide.
尼龙-6 单体的生产。
Manufacture of the nylon-6 monomer.
反应机理图Mechanism
红色弯箭头表示一对电子的移动方向：从电子来源（孤对电子或化学键）指向电子去向。Red curly arrows show where an electron pair moves: from its source (lone pair or bond) to its destination.
肟的羟基质子化
The oxime OH is protonated
与离去基团反式的基团迁移到 N，同时失水
The group anti to the leaving group migrates to N as water leaves
水进攻腈鎓离子
Water attacks the nitrilium ion
亚胺酸
Imidic acid
N-甲基乙酰胺；环己酮肟由此得己内酰胺（尼龙-6 单体）
N-Methylacetamide; cyclohexanone oxime gives caprolactam (nylon-6) this way
年表Timeline
- 1886
贝克曼报道该重排
Beckmann reports the rearrangement
- 1938
施拉克（法本公司）由己内酰胺制得尼龙-6
Schlack (IG Farben) makes nylon-6 from caprolactam