Chemistry › Introduction to organic chemistry
Introduction to organic chemistry
Unit C16 · 3 lessons.
IUPAC names, the kinds of formula, structural and E/Z isomerism, and the curly arrows that show how a mechanism moves electrons make up the language of organic chemistry. A name, a displayed formula and a skeletal formula are three descriptions of one molecule, and a question may ask for any of them.
A mechanism earns its marks arrow by arrow. Each curly arrow starts at a lone pair or at a bond, never at an atom or a charge sign, and ends where the new bond forms or on the atom that takes the pair. E/Z isomerism is decided by the Cahn–Ingold–Prelog priority of the two groups on each carbon of the double bond, so a molecule with no two identical groups can still be E or Z, which the older cis and trans names cannot describe.
On the written papers it is set on AQA Papers 2 and 3, OCR A Papers 2 and 3, Edexcel Papers 2 and 3 and Cambridge Papers 1 and 2.
Specification sections: AQA 3.3.1.1, 3.3.1.3, 3.3.1.2 · OCR A 4.1.1, 4.1.3 · Edexcel 6.1 to 6.31 · CAIE 13.1, 13.3, 13.4, 13.2
Notes
Illustrated notes for each topic in this unit, with worked examples and a checklist of objectives.
- Naming and representing organic molecules
Empirical, molecular, general, structural, displayed and skeletal formulae; homologous series, functional groups and alkyl groups; the thirteen functional groups of A level with their suffixes and prefixes; and the IUPAC rules for naming chains to six carbons, including locants, alphabetical order, di and tri, rings, esters, and molecules with two functional groups; hydrocarbons, saturated and unsaturated; straight, branched and cyclic skeletons; and the shape round each carbon with sp³, sp² and sp hybridisation.
- Structural isomerism and E/Z isomerism
Structural isomerism of three kinds, chain, position and functional group, with examples for C₄H₁₀, C₄H₉Br, C₃H₆O and C₄H₈O; stereoisomerism; E/Z isomerism from restricted rotation about the C=C bond; the Cahn–Ingold–Prelog priority rules; cis and trans as a special case; and the effect on boiling points, melting points and fats.
- Reaction types, curly arrows and how a mechanism is written
Addition, substitution, elimination, oxidation, reduction, hydrolysis, condensation and polymerisation; homolytic and heterolytic bond fission; radicals, nucleophiles and electrophiles with examples; the curly-arrow and fishhook conventions; and how to draw a mechanism with its dipoles, lone pairs and charges, shown on nucleophilic substitution and electrophilic addition.
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