Ammonia substitution
Ammonia attacks the carbon bearing bromine to give an alkylammonium intermediate. A further ammonia molecule removes a proton to release ethylamine; the product can undergo additional alkylation if haloalkane remains.
- Reagents
- Excess NH3 in ethanol
- Conditions
- Heat in an appropriate closed system
- Reaction class
- Ammonia substitution
- Equation
- CH3CH2Br + 2NH3 -> CH3CH2NH2 + NH4Br
Overview
Ammonia attacks the carbon bearing bromine to give an alkylammonium intermediate. A further ammonia molecule removes a proton to release ethylamine; the product can undergo additional alkylation if haloalkane remains.
Transformation
- Equation
- CH3CH2Br + 2NH3 -> CH3CH2NH2 + NH4Br
- Reactants
- Bromoethane + 2 Ammonia
- Products
- Ethylamine + Ammonium bromide
- Reagents
- Excess NH3 in ethanol
- Environment
- Heat in an appropriate closed system
- Reaction class
- Ammonia substitution
- Mechanism
- nucleophilic substitution and deprotonation
- Evidence level
- source-backed molecular example
Scope and limitations
- Scope
- Ammonia displaces bromide; another ammonia molecule accepts a proton.
- Limitations
- Excess ammonia favours the primary amine; further alkylation can occur.
Related reactions
- Hydrolysis: Bromoethane → Ethanol
Hydroxide attacks the saturated carbon bearing bromine while the C-Br bond breaks. This primary-substrate SN2 route replaces bromide with OH and preserves both carbon atoms; aqueous conditions favour this branch over elimination.
- Elimination: Bromoethane → Ethene
The base removes a hydrogen from the carbon next to bromine. The C-H electrons form the C=C pi bond as bromide departs, so elimination removes H and Br without changing the two-carbon skeleton.
- Cyanide substitution: Bromoethane → Propanenitrile
The carbon end of cyanide attacks the primary carbon of bromoethane as bromide leaves. The new C-C bond joins cyanide’s carbon to the original chain, giving a three-carbon nitrile rather than acetonitrile.
References
- Organic Chemistry: Synthesis of AminesJohn McMurry · OpenStax Organic Chemistry · 2023
Supports functional-group chemistry used to curate the linked examples. Checked 2026-09-16; named examples are applications of textbook scope, without claimed experimental yields.