AQA A-level CHEMISTRY ORGANIC AND PHYSICAL CHEMISTRY MARKING SCHEME PAPER 2 2020|100% VERIFIED

OH CH3 CH3CH2 OH allowed allowed not allowed not allowed not allowed NH2NO2 NH2 NH2 NH2 allowed allowed allowed allowed not allowed CN C COOH CN COOH COOH not allowed not allowed not allowed not allowed not allowed CHO not allowed not allowed not allowed not allowed not allowed CHO COCl CHO COCl • Representation of CH2 by C−H2 will be penalised • Some examples are given here of structures for specific compounds that should not gain credit (but, exceptions may be made in the context of balancing equations). CH3COH for ethanal CH3CH2HO for ethanol • In most cases, the use of ‘sticks’ to represent C ─ H bonds in a structure should not be penalised. The exceptions to this when “sticks” will be penalised include • structures in mechanisms where the C ─ H bond is essential (eg elimination reactions in halogenoalkanes and alcohols) • when a displayed formula is required • when a skeletal structure is required or has been drawn by the candidate. 3.13 Organic names As a general principle, non-IUPAC names or incorrect spelling or incomplete names should not gain credit. Some illustrations are given here. Unnecessary but not wrong numbers will not be penalised such as the number ‘2’ in 2methylpropane or the number ‘1’ in 2-chlorobutan-1-oic acid. but-2-ol should be butan-2-ol 2-hydroxybutane should be butan-2-ol butane-2-ol should be butan-2-ol 2-butanol should be butan-2-ol ethan-1,2-diol should be ethane-1,2-diol 2-methpropan-2-ol should be 2-methylpropan-2-ol 2-methylbutan-3-ol should be 3-methylbutan-2-ol 3-methylpentan should be 3-methylpentane 3-mythylpentane should be 3-methylpentane 3-methypentane should be 3-methylpentane propanitrile should be propanenitrile aminethane should be ethylamine (although aminoethane can gain credit) 2-methyl-3-bromobutane should be 2-bromo-3-methylbutane 3.14 Organic reaction mechanisms Curly arrows should originate either from a lone pair of electrons or from a bond. The following representations should not gain credit and will be penalised each time within a clip. H3C .. Br H3C. .Br .. _ :OH OH For example, the following would score zero marks When the curly arrow is showing the formation of a bond to an atom, the arrow can go directly to the relevant atom, alongside the relevant atom or more than half-way towards the relevant atom. In free-radical substitution • the absence of a radical dot should be penalised once only within a clip. • the use of half-headed arrows is not required, but the use of double-headed arrows or the incorrect use of half-headed arrows in free-radical mechanisms should be penalised once only within a clip