Study guides
Organic Chemistry
3 guides for this subject — how to prepare, what to practise, and how to know it has gone in.
A practice question
Choose an answer and it is marked, with the explanation. From Organic Chemistry Practice Questions: 10 Worked MCQs.
1-bromopropane is heated with excess sodium iodide in dry acetone. What is the major organic product?
1-iodopropane is formed by an SN2 substitution: iodide attacks the primary carbon bearing bromine and bromide leaves. Prop-1-ene is an elimination product, but elimination is disfavoured for a primary substrate under these conditions. 2-iodopropane would require rearrangement or substitution at the wrong carbon, and water or hydroxide would be needed for propan-1-ol.
A spoken answer, marked
An examiner's question, answered out loud and marked criterion by criterion. From Organic Chemistry Viva Questions: Practical Practice Guide.
Examiner
Acetophenone is treated with sodium borohydride, followed by aqueous work-up. What product forms, how does the mechanism proceed, and what stereochemical outcome do you expect?
Identifies 1-phenylethanol and reduction of the ketone to a secondary alcohol.
ImproveName the product before describing the steps.
Explains hydride attack at the carbonyl carbon and formation of an alkoxide.
ImproveShow that the C=O pi electrons move onto oxygen.
Recognises formation of a stereogenic carbon but does not explain why both faces can be attacked.
ImproveExplain that the carbonyl is planar and the reagent is achiral, so attack on either face gives a racemic mixture.
Mentions aqueous work-up but does not say that it protonates the alkoxide.
ImproveState that protonation of the alkoxide gives the alcohol.
A strong answerAcetophenone is reduced to 1-phenylethanol, a secondary alcohol. A hydride from borohydride attacks the electrophilic carbonyl carbon, and the C=O pi electrons move onto oxygen to form an alkoxide. Aqueous work-up protonates that alkoxide. The product carbon bearing OH is stereogenic. Because the carbonyl is planar and the reagents are achiral, attack on either face gives a racemic mixture.
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Guides
- How to Study Organic Chemistry: A Practical GuideLearn how to study organic chemistry with a structured method for mechanisms, reactions, stereochemistry, synthesis and spectroscopy.
- Organic Chemistry Practice Questions: 10 Worked MCQsTest organic chemistry with 10 exam-style practice questions on mechanisms, spectroscopy, stereochemistry and synthesis, with worked explanations.
- Organic Chemistry Viva Questions: Practical Practice GuidePractise organic chemistry viva questions on mechanisms, reaction conditions and spectroscopy with a structured method and worked sample answers.
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