Hydrolysis
The C-Br bond can be displaced by hydroxide to form an alcohol.
- Reagents
- aqueous NaOH or KOH
- Conditions
- warm
- Reaction class
- nucleophilic substitution
- Equation
- R-Br + OH- -> R-OH + Br-
Overview
The C-Br bond can be displaced by hydroxide to form an alcohol.
Transformation
- Equation
- R-Br + OH- -> R-OH + Br-
- Reagents
- aqueous NaOH or KOH
- Environment
- warm
- Reaction class
- nucleophilic substitution
- Mechanism
- nucleophilic substitution
- Evidence level
- textbook core
Reference procedure
Comparative hydrolysis and bromide release
1-bromobutane: water substitution with silver-bromide detection
Materials and quantities
- 1-bromobutane
- Ethanol, water and silver nitrate at the cited comparison conditions
Apparatus
- Matched tubes
- Water bath and timer
Procedure
- Record the time to a cream precipitate under the same conditions as the other two primary halogenoalkanes.
Work-up and isolation
- The alcohol remains in a mixture; no purified yield is determined.
Critical controls
- The expected relative timing is intermediate. Precipitation detects released bromide, not the alcohol directly.
- Water is the nucleophile here; the preparative aqueous-hydroxide route uses different conditions.
Practical techniques
Controlled heating
Apply the stated temperature deliberately, using a heat source and vessel suited to the solvent, scale and required temperature rather than treating ‘heat’ as a complete procedure.
Setup
- Select the bath from the cited temperature: a water bath is limited to temperatures near 100 °C, while higher temperatures require an appropriate oil or sand bath or another specified heater.
- Clamp the vessel securely and position the temperature probe so it measures the reaction or bath consistently without touching the heater.
- Use a vented arrangement unless the cited method explicitly specifies pressure-rated equipment; ordinary glassware must not be improvised as a sealed reactor.
- Bring the mixture to the stated temperature gradually and start timing only after the working temperature is reached.
Operating checks
- Use electric heating rather than a naked flame for flammable organic solvents.
- Add anti-bumping granules before heating, not to a hot liquid.
- Do not infer a temperature, duration or scale when the source gives only the word ‘heat’; obtain the substrate-specific procedure first.
Controlled comparison of reaction times
Compare a visible change while keeping variables other than the one under study consistent.
Setup
- Use equal concentrations, volumes and mixing methods, and equilibrate samples at the same temperature.
- Define the visible endpoint before starting and record repeated measurements.
Operating checks
- Precipitation time includes mixing and detection thresholds; its inverse is only a relative-rate proxy under matched conditions.
- Do not compare different carbon skeletons when isolating the effect of halogen identity.
Scope and limitations
- Scope
- Hydrolysis of bromoalkanes with aqueous hydroxide.
- Limitations
- Aqueous hydroxide favours substitution; ethanolic hydroxide favours elimination. The mechanism diagram uses a primary bromoalkane exemplar and should not be read as a universal pathway for tertiary bromoalkanes.
Related reactions
- Chlorination: Alcohols → Chloroalkanes
Alcohols can be converted into chloroalkanes to create a better leaving group for downstream substitution.
- Chlorination with thionyl chloride: Alcohols → Chloroalkanes
Thionyl chloride converts alcohols into chloroalkanes with sulfur dioxide and hydrogen chloride as by-products.
- Bromination: Alcohols → Bromoalkanes
Bromide and acid conditions convert alcohols into bromoalkanes.
- Iodination: Alcohols → Iodoalkanes
Iodine and red phosphorus conditions convert alcohols into iodoalkanes.
- Hydrobromination: Alkenes → Bromoalkanes
Addition of hydrogen bromide across an alkene can form a bromoalkane.
- Hydrolysis: Chloroalkanes → Alcohols
The C-Cl bond can be displaced by hydroxide to form an alcohol.
- Cyanation: Bromoalkanes → Nitriles
Cyanide substitution forms a nitrile and extends the carbon chain by one carbon.
- Amination: Bromoalkanes → Amines
Ammonia substitutes bromide to form a primary amine; excess ammonia limits further alkylation.
- Hydrolysis: Iodoalkanes → Alcohols
The C-I bond can be displaced by hydroxide to form an alcohol.
- Elimination: Bromoalkanes → Alkenes
Base-promoted elimination removes HBr to form an alkene.
- Oxidation: Alcohols → Aldehydes
Controlled oxidation of a primary alcohol gives an aldehyde.
- Oxidation: Alcohols → Ketones
Oxidation of a secondary alcohol gives a ketone.
- Oxidation: Alcohols → Carboxylic acids
Full oxidation of a primary alcohol gives a carboxylic acid.
- Free radical bromination: Alkanes → Bromoalkanes
Photochemical bromination can convert alkanes into bromoalkanes.
- Hydration: Alkenes → Alcohols
Catalytic hydration converts alkenes into alcohols.
- Dehydration: Alcohols → Alkenes
Dehydration converts alcohols into alkenes.
References
- Pearson Edexcel Level 3 Advanced GCE in Chemistry specificationPearson Education Limited · Pearson qualifications · 2024
Supports the textbook-core organic reaction routes used for displayed route and mechanism content.
- Core practical 4: Investigate the hydrolysis of halogenoalkanesPearson Education Limited · Pearson qualifications
Matched halogenoalkane comparisons, ethanol/water medium and precipitation timing.
- Rates of hydrolysis: practical videos for 16–18 studentsRoyal Society of Chemistry · RSC Education
Water is the nucleophile in the silver-nitrate comparison, and silver-halide precipitation measures released halide indirectly.
- Pearson Edexcel International Advanced Level Chemistry Student Practical GuidePearson Education Limited · Pearson qualifications · 2018
Supports the practical distinctions between reflux, distillation, liquid-liquid separation, washing and drying in organic preparations.