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

Swern Oxidation Oxidation of Secondary Alcohol to Ketone Claisen Condensation (Ethyl Acetate) Kolbe Electrolysis Baeyer-Villiger Oxidation Beckmann Rearrangement (Cyclohexanone Oxime) Catalytic Hydrogenation of Ethylene Condensation Polymerization (Nylon 6,6) Cope Rearrangement Epoxidation of Alkenes (mCPBA)

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.