S3.2 Functional Group Chemistry

• S3.2.7—Stereoisomers have the same constitution (atom identities, connectivities and bond multiplicities) but different spatial arrangements of atoms.

  • Describe and explain the features that give rise to cis-trans isomerism; recognize it in non-cyclic alkenes and C3 and C4 cycloalkanes.

  • Draw stereochemical formulas showing the tetrahedral arrangement around a chiral carbon. Describe and explain a chiral carbon atom giving rise to stereoisomers with different optical properties.

  • Recognize a pair of enantiomers as non-superimposable mirror images from 3D modelling (real or virtual).

Structure 2.2—What features of a molecule determine whether it is IR active or not?

Reactivity 1.3—What properties of a greenhouse gas determine its “global warming potential”?

• S3.2.8—Mass spectrometry (MS) of organic compounds can cause fragmentation of molecules.

  • Deduce information about the structural features of a compound from specific MS fragmentation patterns.

• S3.2.9—Infrared (IR) spectra can be used to identify the type of bond present in a molecule.

  • Interpret the functional group region of an IR spectrum, using a table of characteristic frequencies (wavenumber/cm–1).

• S3.2.10—Proton nuclear magnetic resonance spectroscopy (1H NMR) gives information on the different chemical environments of hydrogen atoms in a molecule.

  • Interpret 1H NMR spectra to deduce the structures of organic molecules from the number of signals, the chemical shifts, and the relative areas under signals (integration traces).

• S3.2.11—Individual signals can be split into clusters of peaks.

  • Interpret 1H NMR spectra from splitting patterns showing singlets, doublets, triplets and quartets to deduce greater structural detail.

• S3.2.12—Data from different techniques are often combined in structural analysis.

  • Interpret a variety of data, including analytical spectra, to determine the structure of a molecule.

Structure 2.2—What features of a molecule determine whether it is IR active or not?

Reactivity 1.3—What properties of a greenhouse gas determine its “global warming potential”?