Advanced organic mechanisms, synthetic pathways, polymer chemistry, and spectroscopic structure determination for OxfordAQA International A-Level Chemistry (Specification 9620). Complete unit topic notes, mechanism guides, and assessment advice.
Unit 4 (CH04) is the advanced organic chemistry modular component of the OxfordAQA International A-Level qualification. It broadens the fundamental mechanisms studied in AS Unit 2 (CH02) into complex nucleophilic additions, nucleophilic addition-eliminations, electrophilic aromatic substitutions, condensation polymerisations, biological macromolecules, and multi-dimensional NMR spectroscopic elucidations.
Like CH03, Unit CH04 is examined in both the January series and the May/June series. Candidates benefit from sit and resit opportunities to lock in an optimal UMS score before cashing in the full A-Level.
Examiners place extraordinary weight on curly arrow precision. Arrows must originate unambiguously from a lone pair of electrons or the center of a covalent bond, and terminate precisely on the destination atom or bond. Differentiating nucleophilic addition (carbonyls) from nucleophilic addition-elimination (acyl chlorides/anhydrides) is vital.
Practice authentic 80-mark mock examinations under timed conditions: 15 Section A multiple choice questions and 6 Section B structured questions with full mark schemes and examiner tips.
Select a syllabus node below to access comprehensive revision notes, illustrated mechanisms, worked synthesis routes, and exam-style practice questions:
Chiral carbon stereocentres, non-superimposable mirror image enantiomers, polarimetry plane-polarised light rotation, and racemic mixture formation from planar carbonyl groups (optical-isomerism).
Open Topic Notes →Structure and reactivity of carbonyls, oxidation tests with Tollens and Fehling reagents, reduction using NaBH4, and nucleophilic addition mechanisms with KCN / HCN.
Open Topic Notes →Carboxylic acids, esterification, base hydrolysis (saponification), acyl chlorides, acid anhydrides, and nucleophilic addition-elimination mechanisms (carboxylic-acids-derivatives).
Open Topic Notes →Aromatic-chemistry: Kekule vs delocalised ring model, thermodynamic stability evidence from hydrogenation enthalpies, and electrophilic substitution mechanisms (nitration and Friedel-Crafts acylation).
Open Topic Notes →Classification of amines, comparative Bronsted-Lowry base strengths, nucleophilic substitution syntheses, reduction of nitriles and nitrobenzene, and quaternary ammonium salt cationic surfactants.
Open Topic Notes →Step-growth condensation polymers, Terylene (PET) polyester, Nylon 6,6 and Kevlar polyamides, repeating unit identification, hydrolysis breakdown, and comparison with addition polymers.
Open Topic Notes →Zwitterions, isoelectric points, peptide bond formation, primary secondary and tertiary protein structures, enzyme active site stereospecificity, and DNA nucleotide bonding (amino-acids-proteins-dna).
Open Topic Notes →Comprehensive synthesis-and-analysis: multi-step organic synthetic design, retro-synthesis, carbon-13 NMR chemical shifts, and high-resolution proton 1H NMR chemical shifts, integration, and (n+1) splitting patterns.
Open Topic Notes →