nmr, chirality, carbonyls, carboxylic acids & esters definitions

NMR spectroscopy

NMR spectroscopy is an analytical technique that allows the structure of a molecule to be determined by analysing bond & atom environments.

The environment of an atom…

depends on the surrounding atoms and bonds in the molecule.

Stereoisomers

are molecules that have the same structural formula but a different arrangement of atoms in space. (The two types of stereoisomerism are E-Z and optical)

Optical isomers

are non-superimposable mirror images which rotate the plane of plane-polarised light in an equal amount but opposite directions.

Plane-polarised light

oscillates in one plane.

polarimeter

can be used to measure the rotation of plane-polarised light (by enantiomers).

Chiral carbon

four different groups bonded to it. (sometimes referred to as a ‘chiral centre’ or an asymmetric carbon

Enantiomers

optical isomers of the same molecule are referred to as enantiomers.

Racemic mixture

50-50 mixture of the two enantiomers of an optical isomer. (Does not rotate the plane of plane-polarised light as the rotations cancel)

Carbonyl compounds

aldehydes or ketones. The carbonyl group is C=O.

Hydrolysis

a reaction in which a compound is split apart in a reaction involving water.

Condensation

reactions join two molecules together via the removal of a small molecule (often water but not always).

Condensation polymers

Produced when monomers join together via condensation reactions. This type of polymerisation produces the polymer and a small molecule.