87970-37-4Relevant articles and documents
CPMAS 13C NMR Spectra of Quinones, Hydroquinones, and Their Complexes. Use of CMR To Follow a Reaction in the Solid State
Scheffer, J. R.,Wong, Y.-F.,Patil, A. O.,Curtin, D. Y.,Paul, I. C.
, p. 4898 - 4904 (2007/10/02)
CPMAS 13C NMR spectroscopy has been employed to follow the reaction at temperatures above 70 deg C of the crystalline 1/1 complex of 1,4-benzoquinone with 2,5-dimethyl-1,4-hydroquinone to give the 1/2 complex of 2,5-dimethyl-1,4-benzoquinone-hydroquinone and an equimolar amount of 2,5-dimethyl-1,4-benzoquinone.The redox reaction of a solid mixture of quinhydrone (1,4-benzoquinone-1,4-hydroquinone) with an equimolar amount of 2,5-dimethyl-1,4-hydroquinone gives the 1/2 complex of 2,5-dimethyl-1,4-benzoquinone with 1,4-hydroquinone with no evidence of formation of side products or accumulation of reaction intermediates.During preparation of a mixture of the 1/1 complex of 1,4-benzoquinone-2,5-dimethylhydroquinone with an equimolar amount of 1,4-hydroquinone the partial exchange of one hydroquinone for another in the complex occurs even during mixing of the components at room temperature.An equimolar mixture of 1,4-benzoquinones, 1,4-hydroquinone, and 2,5-dimethyl-1,4-hydroquinone underwent partial complexation at room temperature.These latter two mixtures when heated in the solid state each gave the 1/2 complex 2,5-dimethyl-1,4-benzoquinone-1,4-hydroquinone.As background for this work, CMR spectra of some crystalline quinones, hydroquinones, and their complexes (quinhydrones) have been obtained.The differences between the solid-state and corresponding solution spectra have been shown to be primarily in the multiplicities of some resonances but not others.It is suggested that a primary source of multiplicities in the quinones is CH---O interactions of the sort discussed by others in the analysis of the crystal packing patterns of such compounds.
SOLID-STATE FORMATION OF QUINHYDRONES FROM THEIR COMPONENTS. USE OF SOLID-SOLID REACTIONS TO PREPARE COMPOUNDS NOT ACCESSIBLE FROM SOLUTION.
Patil,Curtin,I. C. Paul
, p. 348 - 353 (2007/10/02)
Selective molecular mobility provided by working with crystalline solids has been employed to prepare unsymmetrically substituted quinhydrones too unstable with respect to self-oxidation-reduction to be prepared by crystallization from solution. Reaction is carried out by grinding the solid components together with a mortar and pestle. Examination of the products with differential scanning calorimetry, X-ray powder photography, and Fourier transform infrared spectroscopy shows that the complexation reaction goes to completion under conditions in which no detectible redox reaction has occurred. The products are shown by X-ray powder photography to be formed in a microcrystalline state.
