Crystallography of the simpler quinones

Abstract

The hydrocarbons benzene, naphthalene, and anthracene each yield an ortho- and a para-quinone, all of which are solid at ordinary temperatures. In general, the para-quinones are stable and easier to prepare than the ortho-quinones; chemical interest has settled chiefly about benzoquinone and ordinary (meso-) anthraquinone, and these are the only members of the series of which the crystal morphology has been well studied. In the present investigation, crystals of all the quinones concerned (except orthobenzoquinone, which is exceedingly unstable) have been prepared and described, the dimensions and symmetry of their unit cells have been worked out, and crystal structures have been assigned as far as possible. The β-angles of the monoclinic crystals have been derived from the X-ray data alone. The X-ray spectrograms were obtained with copper radiation, pinhole beams and photographic plates being used for the most part. The spectrometer, which was constructed in the laboratory workshop, was of a simple type adaptable to either rotation or oscillation photographs as desired. The somewhat volatile crystals of benzoquinone and 1-4 naphthoquinone were covered, during photography, with gelatine capsules.