Unit 4: Structure, synthesis and design
12 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.
Topic 1: Properties and structure of organic materials
Multi-step organic synthesis. Assembles the Unit 4 reaction toolkit (substitution, addition, oxidation, esterification, hydrolysis) into reaction pathway maps, with worked syntheses of ethyl ethanoate from ethene and a haloalkane from an alkane. Includes the QCAA pathway-diagram conventions for IA3 and EA.
Isomerism. Distinguishes chain, position and functional-group isomers, sets out the conditions for cis-trans isomerism in alkenes, and works through C4H8O3 and 1,2-dichloroethene examples. Highlights the property differences QCAA tests in IA3 secondary data.
Physical properties of organic compounds. Connects boiling point and solubility trends to dispersion forces, dipole-dipole, and hydrogen bonding. Compares alcohols, aldehydes, ketones, carboxylic acids and amides at matched Mr and explains chain length and branching effects for IA3 and EA.
IUPAC nomenclature and functional groups. Covers the ten core homologous series, the suffix/prefix priority order, locant numbering rules, and worked names for substituted alkenes, alcohols and esters. Includes the structural-formula skeletal/condensed conventions QCAA accepts.
Alkane and alkene reactivity. Sets out free-radical substitution of alkanes by halogens (UV initiation) and electrophilic addition of alkenes (halogens, hydrogen halides, hydrogen, water) with Markovnikov's rule for unsymmetrical alkenes. Includes the bromine-water test and the IA3 / EA expected products for each.
Alcohol oxidation and esterification. Distinguishes primary, secondary and tertiary alcohols by oxidation behaviour, gives the acidified-dichromate / permanganate observation colours, and works through the Fischer esterification of ethanoic acid with ethanol. Includes acid hydrolysis as the reverse reaction.
Topic 2: Chemical synthesis and design
Green chemistry. Defines the 12 principles of green chemistry, sets out the atom economy calculation, contrasts atom economy with percentage yield, and applies the principles to ester synthesis, biodiesel production and ibuprofen manufacture. The high-yield IA3 evaluation framework.
Mass spectrometry and IR spectroscopy. Explains the molecular ion (M+) and fragmentation peaks in MS, the diagnostic IR absorption ranges (O-H, N-H, C=O, C-O, C-H), and walks through identifying an unknown C3H6O2 from its MS and IR spectra. The standard QCAA IA3 / EA spectroscopy item.
Proton NMR spectroscopy. Explains chemical environments, chemical shifts (with the QCAA reference table), the n+1 splitting rule, and integration. Walks through the 1H NMR of ethanol and ethyl ethanoate, the canonical IA3 / EA spectra.
Addition polymerisation. Shows the monomer to repeat-unit conversion for polyethene, polypropene, PVC, polystyrene and PTFE; explains LDPE vs HDPE in terms of branching and crystallinity; and links polymer structure to softening behaviour, density and chemical resistance for IA3 product-design questions.
Condensation polymers and biomolecules. Distinguishes condensation from addition polymerisation, sets out polyester (PET) and polyamide (nylon-6,6) formation, then maps the same chemistry onto proteins, carbohydrates and triglycerides for IA3 biomolecule contexts.
Chromatography. Explains the stationary/mobile phase principle, Rf values in TLC, retention times in GC and HPLC, and the use of calibration curves for quantification. Includes the canonical food and pharmaceutical IA3 / EA contexts.