E2 Elimination (Dehydrohalogenation)

C2H5Br + KOH → C2H4 + KBr + H2O

概要

Strong base (KOH in ethanol) removes a beta-hydrogen and the halide leaves simultaneously in a concerted E2 elimination to form an alkene. The H and Br must be anti-periplanar (180 degrees) for the elimination to proceed. E2 competes with SN2, with bulky bases and secondary/tertiary substrates favoring elimination.

参加者

役割 物質 係数 状態
反応物 Potassium Hydroxide KOH 1 (aq)
生成物 Ethylene C₂H₄ 1 (g)
生成物 Water H₂O 1 (l)

日常の例

E2 elimination is used to prepare alkenes from easily available alkyl halides and is key to understanding organic reaction selectivity.

産業上の重要性

脱ハロゲン化水素反応は塩化ビニル（二塩化エチレンから）の製造や製薬合成での不飽和化合物の調製に使われる。ハロゲン化アルキルからオレフィンへの変換に広く応用される。

特性

タイプ
Organic
可逆的
いいえ
エネルギー
発熱性
ΔH
-50.0 kJ/mol

関連する反応

Epoxidation of Alkenes (mCPBA) Swern Oxidation Oxidation of Secondary Alcohol to Ketone Claisen Condensation (Ethyl Acetate) Aldol Condensation of Acetaldehyde Kolbe Electrolysis Baeyer-Villiger Oxidation Beckmann Rearrangement (Cyclohexanone Oxime) Catalytic Hydrogenation of Ethylene Dehydration of Ethanol

Frequently Asked Questions

What is the equation for E2 Elimination (Dehydrohalogenation)?
The balanced equation is: C₂H₅Br + KOH → C₂H₄ + KBr + H₂O.
What type of reaction is E2 Elimination (Dehydrohalogenation)?
E2 Elimination (Dehydrohalogenation) is a organic reaction.
Is E2 Elimination (Dehydrohalogenation) exothermic or endothermic?
E2 Elimination (Dehydrohalogenation) is exothermic (releases energy). The enthalpy change (ΔH) is -50.0 kJ/mol.