Reactions of Organic Compounds: Flashcards
Revise addition, substitution, elimination, oxidation and condensation reactions, and the bromine-water and dichromate tests.
Reactions of Organic Compounds: Flashcards
- QuestionWhat is an addition reaction?Answer
Two molecules join to form one; in alkenes the C=C opens and an atom or group adds to each carbon.
- QuestionWhat is a substitution reaction?Answer
One atom or group is replaced by another, e.g. CH₄ + Cl₂ → CH₃Cl + HCl (in UV light).
- QuestionWhat is an elimination reaction?Answer
A small molecule is removed and a C=C forms, e.g. ethanol → ethene + water (conc. H₂SO₄, heat).
- QuestionTest for a C=C double bond?Answer
Orange-brown bromine water is decolourised by an alkene (addition). Alkanes leave it orange.
- QuestionProducts of ethene with H₂ (Ni), HBr and steam (H⁺)?Answer
Ethane, bromoethane and ethanol (all addition).
- QuestionWhat does a haloalkane give with aqueous OH⁻?Answer
An alcohol (substitution), e.g. CH₃CH₂Br + OH⁻ → CH₃CH₂OH + Br⁻.
- QuestionOxidation of a primary alcohol with acidified dichromate?Answer
Aldehyde (distil off at once), then carboxylic acid (heat under reflux). Orange → green.
- QuestionOxidation of secondary and tertiary alcohols?Answer
Secondary → ketone. Tertiary → no reaction (dichromate stays orange).
- QuestionWhat is a condensation reaction?Answer
Two molecules join and release a small molecule, usually water, e.g. acid + alcohol ⇌ ester + water.
- QuestionState Markovnikov's rule.Answer
When HX adds to an unsymmetrical alkene, H goes to the carbon that already has more H atoms: propene + HBr gives mainly 2-bromopropane.
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