The structure of resorcinol a quantitative X-ray investigation

Previous investigations of organic crystals have served to determine the dimensions and structure of the aromatic carbon ring and of certain simple substituent groups. The hydroxyl group is particularly interesting, both in relation to chemistry and in the physical explanation of its associating properties. A considerable number of metallic hydroxides has been studied by X-ray analysis, and the results show that the occurrence of the —OH group is generally characterized in the solid state by unusually small intermolecular distances. It is obviously of the greatest importance to study the dimensional properties of these groups in organic acids, phenols, and alcohols, but until now few really quantitative investigations along these lines have been carried out. The properties of the phenols, intermediate as they are between those of the acids and the alcohols, would lead us to expect the characteristic hydroxyl or hydrogen bond distances (2·5 to 2·8 A) between the reactive groups on adjoining molecules; but the question arises whether this can be achieved in the crystal structure without sacrificing the usual minimum van der Waals distance of about 3·5 A, between some of the aromatic carbon atoms of the molecules. The solution of the present structure shows that these two distinct sets of intermolecular distances are, in fact, retained without bringing in any intermediate values.