AS and A2 Chemistry notes and resources (WJEC specification) - UNIT CH4 Spectroscopy and Organic Chemistry (Analysing and building molecules)

This unit builds on the foundation ideas of spectroscopy and basic organic chemistry introduced at AS level and goes on to explore these concepts in more detail. It also explores the use of these topics in structure elucidation, in synthesis and in industrial and environmental applications.

TOPIC 10 - Isomerism and aromaticity

Candidates should be able to:

(a) give the systematic names of all simple compounds, including benzene derivatives, containing the functional groups occurring in this Unit;

(b) understand the term stereoisomerism as embracing both E.Z and optical isomerism;

(c) explain what is meant by a chiral centre, recall that this gives rise to optical isomerism, and be able to identify chiral centres in given molecules, and understand what is meant by an enantiomer;

(d) recall that enantiomers rotate plane-polarised light in opposite directions and that equimolar amounts of enantiomers form racemic mixtures;

(e) describe the structure of, and bonding in, benzene;

(f) calculate the delocalisation or resonance energy of benzene from given enthalpy data;

(g) describe and classify the nitration and halogenation reactions of benzene as electrophilic substitution, and recall the mechanism for these reactions ¢Ó*; (The equation for the formation of NO2 +is not required.)

(h) describe the Friedel-Crafts alkylation of benzene ¢Ó*;

(i) compare benzene and alkenes with respect to benzene's resistance to addition and explain this resistance in terms of ¥ð electron delocalisation;

(j) compare the ease of alkaline hydrolysis of chloroalkanes and chlorobenzene and explain the difference in terms of the C . Cl bond strength, and rationalise the greater strength of the C . C1 bond in the latter case;