定义Definition
环氧化反应是把烯烃转化为三元环醚（环氧化物）的氧化反应，常用过氧酸（m-CPBA，普里列扎耶夫反应）、过氧化氢/催化剂或工业上银催化的氧气氧化。
Epoxidation oxidises an alkene to a three-membered cyclic ether (epoxide), commonly with peracids (m-CPBA; the Prilezhaev reaction), hydrogen peroxide with catalysts, or industrially with oxygen over silver.
过氧酸机理Peracid mechanism
“蝴蝶”机理：过氧酸的末端氧在一步协同过程中转移到双键上，同时质子内转移并放出羧酸。加成是立体专一的同面加成，烯烃的顺反关系保持。富电子烯烃（取代多）反应更快。
Butterfly mechanism: the peracid’s terminal oxygen is delivered in one concerted step with internal proton transfer, releasing the acid. The addition is stereospecific and suprafacial, preserving alkene geometry; electron-rich (more substituted) alkenes react faster.
其他方法Other methods
缺电子烯烃（烯酮）用碱性 H₂O₂（魏茨–舍弗反应）；不对称环氧化：烯丙醇用夏普莱斯法，非官能化烯烃用雅各布森–香月（Mn-salen）或史一安（果糖衍生酮）法。工业上乙烯 + O₂ 经银催化得环氧乙烷，丙烯用 H₂O₂/钛硅分子筛（HPPO 法）得环氧丙烷。
Electron-poor enones use basic H₂O₂ (Weitz–Scheffer); asymmetric versions include Sharpless (allylic alcohols), Jacobsen–Katsuki (Mn-salen) and Shi (fructose-derived ketone). Industrially ethylene + O₂ over silver gives ethylene oxide, and propylene + H₂O₂ over titanium silicalite gives propylene oxide (HPPO).
由来Origin
俄国化学家尼古拉·普里列扎耶夫于 1909 年报道过氧苯甲酸环氧化烯烃。
Reported by the Russian chemist Nikolai Prilezhaev in 1909 using perbenzoic acid.
反应Reactions
m-CPBA/CH₂Cl₂，0 °C 至室温，常加 NaHCO₃ 缓冲
m-CPBA in CH₂Cl₂ at 0 °C to room temperature, often buffered with NaHCO₃
过氧酸与烯烃形成螺旋形过渡态。
Peracid and alkene form a spiro-type transition state.
氧原子同面转移，同时质子转移。
Oxygen transfers suprafacially with proton transfer.
生成环氧化物与羧酸。
Epoxide and carboxylic acid form.
构型保持。
Configuration retained.
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.
“蝴蝶”过渡态：四对电子同时移动，O 加到双键同一侧
“Butterfly” transition state: four electron pairs move at once; O adds to one face
环氧化物；顺式烯烃得顺式环氧化物（立体专一）
Epoxide; a cis-alkene gives the cis-epoxide (stereospecific)
年表Timeline
- 1909
普里列扎耶夫反应
Prilezhaev reaction
- 1931
银催化乙烯直接氧化（勒福尔）
Lefort’s silver-catalysed direct oxidation of ethylene
- 1980
夏普莱斯不对称环氧化
Sharpless asymmetric epoxidation
- 1990
雅各布森–香月环氧化
Jacobsen–Katsuki epoxidation