Back to the full dot-point answer
VICChemistryQuick questions
Unit 4: How are organic compounds categorised, analysed and used?
Quick questions on Organic reactions and reaction pathways: VCE Chemistry Unit 4
14short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the five reaction types you need?Show answer
1. Substitution (R-X to R-Y). One atom or group on a saturated carbon is replaced by another. The skeleton stays the same.
What is markovnikov's rule?Show answer
For an unsymmetric alkene reacting with an unsymmetric reagent like HBr or H2O, the H goes to the carbon with more hydrogens (the less-substituted end), and the other group (Br, OH) goes to the carbon with fewer hydrogens (the more-substituted end). The major product is the one with the more-substituted carbocation intermediate.
What is multi-step pathway design?Show answer
The classic alkane-to-ester pathway is:
What is 1. Substitution?Show answer
One atom or group on a saturated carbon is replaced by another. The skeleton stays the same.
What is 2. Addition?Show answer
Two atoms or groups add across C=C or C triple C, converting the molecule from unsaturated to (more) saturated.
What is 3. Oxidation?Show answer
Acidified K2Cr2O7 / H2SO4 (or KMnO4 / H2SO4) under reflux.
What is 4. Condensation?Show answer
Two small molecules combine into a larger molecule with loss of a small molecule (usually water). The key example is esterification:
What is 5. Hydrolysis?Show answer
Adding water (often with acid or base catalyst) cleaves an ester or amide bond back to the carboxylic acid + alcohol (or carboxylic acid + amine).
What is forgetting catalyst/conditions?Show answer
A reagent without conditions is not a complete answer. Reflux is the default for liquid-phase reactions; UV light for the alkane chlorination; H2SO4 for esterification.
What is oxidising a tertiary alcohol?Show answer
Tertiary alcohols do not oxidise under K2Cr2O7 / H2SO4 (no H on the OH carbon to lose). A "no reaction" answer is correct.
What is adding HBr to an alkene the wrong way?Show answer
Markovnikov: H goes to the side with more Hs already (less substituted side); Br goes to the more substituted side.
What is forgetting that esterification is reversible?Show answer
State the equilibrium and how to drive it (excess alcohol or acid, removing water).
What is confusing condensation and addition?Show answer
Condensation produces a small molecule by-product (water). Addition does not (everything ends up in the product).
What is using KOH in water for elimination?Show answer
Elimination requires concentrated alkali in ethanol (and heat). KOH in water gives substitution (haloalkane to alcohol).