Structural formula

Common types of structural formula

There are three main types of structural formula in widespread use in the chemical literature.^[1]

Condensed formulae

In early organic chemistry publications, where use of graphics was severely limited, a text-based system arose to describe organic structures in a line of text. Although this system tends to break down with complex cyclic compounds such as ethanol (CH₃CH₂OH).

Skeletal formulae

Main article: skeletal formula

Note that for line drawings of structural formula are assumed to have carbon atoms at the vertices and termini of all line segments not marked with the atomic symbol of an element (other than carbon). Each carbon atom is in turn assumed to bear enough hydrogen atoms to give the carbon atom four bonds. Equivalent full and abbreviated forms are shown in the adjacent figures.

A chemical structure can be precisely, uniquely and unambiguously described using IUPAC nomenclature. In the case of isobutane, the IUPAC systematic name is methylpropane.

Multiple planes

When substituents of a molecule exist in different planes, their position can be described using solid and dotted wedges, with the former showing a substituent coming out of the plane, and the latter going into it. This system is useful in describing differences between chiral molecules.

References

1. ^ Wade, L. G. Organic Chemistry, 4th ed., p 17-20, Prentic Hall, Upper Saddle River, New Jersey, 1999. [ISBN 0-13-922741-5].

See also

• The Chemistry WikiProject's style guidelines for structural formulae.
• The Chemistry WikiProject structure drawing workgroup, for discussing how structures are represented on Wikipedia.