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 13 - Organic synthesis and analysis

Candidates should be able to:

(a) derive empirical formulae from elemental composition data and deduce molecular formulae from these results plus additional data such as titration values, gas volumes, mass spectrometric molecular ion values and gravimetric results;

(b) use given mass spectral data to elucidate the structure of simple organic molecules (up to and including C8 molecules, with one chlorine atom);

(c) interpret given simple infrared spectra using characteristic group frequencies (supplied in cm-1) : O.H(str), N.H (str), C ¡ÕN (str), C=O (str) and N.H (bend) [str = stretch] and use these to identify groupings in organic molecules;

(d) understand that n.m.r. spectra can give information regarding the environment and number of equivalent hydrogen atoms in organic molecules and use such supplied information in structure determination *;

* Candidates will be supplied with simplified n.m.r. spectra of relevant compounds and with a table listing the approximate positions of commonly encountered resonances. They may also be supplied with an indication of the relative peak areas of each resonance and with a note that the splitting of any resonance into n components indicates the presence of n-1 hydrogen atoms on one adjacent carbon, nitrogen or oxygen atom. Questions may be set showing spectra at low resolution where splitting is not shown.

(e) outline the general reaction conditions and basic techniques of manipulation, separation and purification used in organic chemistry, and recall the essential safety requirements during these operations;

(f) understand the use of melting temperatures as a determination of purity;

(g) propose sequential organic conversions by combining a maximum of three reactions in the specification;

(h) deduce percentage yields in preparative processes;

(i) show understanding of the wide applicability of spectroscopic techniques to analytical problems in industry, medicine and the environment;

(j) understand and be able to explain and exemplify the distinction between condensation polymerisation and addition polymerisation;

(k) give, as examples of important industrial and processes, the outline chemistry and any necessary conditions of the manufacture of polyesters (e.g. PET) and polyamides (e.g. Nylon 6 and 6,6) starting from compound(s) containing the respective two functional groups;

(l) outline the uses of thin layer chromatography (TLC), gas chromatography and highperformance liquid chromatography (HPLC) in analysis (details of the theory of chromatography and of the methods used are not required) and be able to find the composition of mixtures by use of retardation factor (Rf), retention time and peak area.