In
chemistry, a Haworth projection is a common way of writing a
structural formula to represent the
cyclic structure of
monosaccharides with a simple three-dimensional perspective. Haworth projection approximate the shapes of the actual molecules better for
furanoses—which are in reality nearly planar—than for
pyranoses which exist in solution in the chair conformation.[1]Organic chemistry and especially
biochemistry are the areas of chemistry that use the Haworth projection the most.
The Haworth projection was named after the British chemist Sir
Norman Haworth.[2]
A Haworth projection has the following characteristics:[3]
Carbon is the implicit type of atom. In the example on the right, the atoms numbered from 1 to 6 are all carbon atoms. Carbon 1 is known as the
anomeric carbon.
Hydrogen atoms on carbon are implicit. In the example, atoms 1 to 6 have extra hydrogen atoms not depicted.
A thicker line indicates atoms that are closer to the observer. In the example on the right, atoms 2 and 3 (and their corresponding OH groups) are the closest to the observer. Atoms 1 and 4 are farther from the observer. Atom 5 and the other atoms are the farthest.
The groups below the plane of the ring in Haworth projections correspond to those on the right-hand side of a
Fischer projection. This rule does not apply to the groups on the two ring carbons bonded to the endocyclic oxygen atom. combined with hydrogen.