Oxidation
Propanal is oxidised to propanoic acid.
- Reagents
- K2Cr2O7 / dilute H2SO4
- Conditions
- Warm in acidic solution
- Reaction class
- Oxidation
- Equation
- CH3CH2CHO + [O] -> CH3CH2COOH
Overview
Propanal is oxidised to propanoic acid.
Transformation
- Equation
- CH3CH2CHO + [O] -> CH3CH2COOH
- Reagents
- K2Cr2O7 / dilute H2SO4
- Environment
- Warm in acidic solution
- Reaction class
- Oxidation
- Mechanism
- aldehyde oxidation
- Evidence level
- source-backed molecular example
Reference procedure
Propanal oxidation: a small-scale silver-ion check
Propanal + Tollens’ reagent → propanoate + metallic silver
Materials and quantities
- Propanal test sample
- Fresh Tollens’ reagent supplied under the laboratory method
Apparatus
- Clean test tube
- Water bath
Procedure
- Apply the source’s small-scale aldehyde comparison using gentle water-bath warming.
- Observe silver deposition against an appropriate blank or ketone control.
Work-up and isolation
- Dispose of the reagent and reaction mixture promptly through the laboratory’s approved process; do not store them.
Critical controls
- The alkaline reagent produces propanoate, not free propanoic acid.
- A silver mirror shows reducing behaviour, not a measured yield or unique identity.
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.
Scope and limitations
- Scope
- Structure-specific simple-aldehyde example.
- Limitations
- Alkaline oxidation gives a propanoate salt.
Related reactions
- Partial oxidation: Propan-1-ol → Propanal
Propan-1-ol is oxidised to propanal.
- Oxidation: Propan-1-ol → Propanoic acid
Propan-1-ol is oxidised to propanoic acid.
- Reduction: Propanal → Propan-1-ol
Propanal is reduced to propan-1-ol.
- Nitrile hydrolysis: Propanenitrile → Propanoic acid
Acid-assisted water addition converts the nitrile through an amide before hydrolysis gives the acid. The nitrile carbon becomes the carboxyl carbon, while its nitrogen leaves the organic skeleton as ammonium.
References
- Oxidation of aldehydes and ketonesJim Clark · Chemguide · 2015
Named molecular examples and reaction scope, checked 2026-09-08.
- The silver mirror test with Tollens’ reagentRoyal Society of Chemistry · RSC Education
Includes a small-scale aldehyde variant and the balanced propanal-to-propanoate reaction; no isolated acid preparation is supplied.
- 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.