Haworth formula

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Relationship between the modes of representation of a molecule ( α- D -glucopyranose ): above ball-and-stick model and conformational formula , below Fischer - correct constitution and Haworth formula.

The Haworth formula (also Haworth projection ) is a method of representation named after the chemist Walter Norman Haworth for ring-shaped five- and six-membered molecules, e.g. B. glucose and fructose in their cyclic form.

The molecule is drawn as a flat hexagon or pentagon , although it is in conformations that are not planar; in the case of six-membered rings, mostly in armchair conformation . In rings with five atoms , an oxygen atom in the ring takes the position in the corner that points away from the observer, so that the pentagon with the opposite edge (bond) points forward. In a six-membered ring, the oxygen receives the back right corner. The carbon atoms follow clockwise in their numbering, but the first carbon atom does not necessarily have to be in position 1. Substituents (and occasionally hydrogen atoms ) are drawn vertically above or below the ring atoms. Substituents pointing to the right in the Fischer projection are at the bottom in the Haworth projection (and vice versa), which enables a molecule to be classified according to the Fischer nomenclature .

Note: FLEA - which at F ischer l is inks, is o ben at H aworth