With respect to reduced coenzyme Q10, there has been no report about the presence of crystal polymorphism, and it has been considered that a conventionally obtained crystal form is only one form. The present invention relates to a reduced coenzyme Q10 crystal having an endothermic peak indicating melting at 542 C. during temperature rise at a rate of 5 C./min by differential scanning calorimetry (DSC), and/or to a reduced coenzyme Q10 crystal showing characteristic peaks at diffraction angles (20.2) of 11.5, 18.2, 19.3, 22.3, 23.0 and 33.3 by powder X-ray (CuK) diffraction. The crystal form is a novel reduced coenzyme Q10 crystal which has a higher melting point and a lower solubility in a solvent, and is more excellent in stability than the conventionally known reduced coenzyme Q10 crystal.

The present invention discloses a process for depolymerization of lignin to yield substituted phenolic monomers using Brnsted ionic liquid as catalyst under mild reaction conditions to obtain an overall yield of monomers up to 97%.

The present invention discloses a process for depolymerization of lignin to yield substituted phenolic monomers using Brnsted ionic liquid as catalyst under mild reaction conditions to obtain an overall yield of monomers up to 97%.

The present invention provides a stabilization method, a preservation method and the like method of reduced coenzyme Q.sub.10, which is useful as functional nutritive foods, specific health foods and the like. Furthermore, the present invention provides a method for efficiently obtaining reduced coenzyme Q.sub.10 of high quality and by a method suitable for a commercial production. It is possible to handle and stably preserve reduced coenzyme Q.sub.10 under a condition that oxidation by a molecular oxygen is inhibited by contacting reduced coenzyme Q.sub.10 with, an ascorbic acid and citric acid or a related compound thereof, and thus a stabilized composition is obtained. Moreover, reduced coenzyme Q.sub.10 is converted into a crystalline state in such a condition that the formation of oxidized coenzyme Q.sub.10 as a byproduct is minimized by crystallizing reduced coenzyme Q.sub.10 in the presence of ascorbic acid or a related compound thereof etc., and thus a reduced coenzyme Q.sub.10 crystal of high quality is produced. Furthermore, by successively crystallizing the generated reduced coenzyme Q.sub.10 in the presence of ascorbic acid or related compound thereof after reducing oxidized coenzyme Q.sub.10 to reduced coenzyme Q.sub.10 using ascorbic acid or a related compound thereof, operations are simplified and minimized, and thus reduced coenzyme Q.sub.10 of high quality is produced.

The present invention provides a stabilization method, a preservation method and the like method of reduced coenzyme Q.sub.10, which is useful as functional nutritive foods, specific health foods and the like. Furthermore, the present invention provides a method for efficiently obtaining reduced coenzyme Q.sub.10 of high quality and by a method suitable for a commercial production. It is possible to handle and stably preserve reduced coenzyme Q.sub.10 under a condition that oxidation by a molecular oxygen is inhibited by contacting reduced coenzyme Q.sub.10 with, an ascorbic acid and citric acid or a related compound thereof, and thus a stabilized composition is obtained. Moreover, reduced coenzyme Q.sub.10 is converted into a crystalline state in such a condition that the formation of oxidized coenzyme Q.sub.10 as a byproduct is minimized by crystallizing reduced coenzyme Q.sub.10 in the presence of ascorbic acid or a related compound thereof etc., and thus a reduced coenzyme Q.sub.10 crystal of high quality is produced. Furthermore, by successively crystallizing the generated reduced coenzyme Q.sub.10 in the presence of ascorbic acid or related compound thereof after reducing oxidized coenzyme Q.sub.10 to reduced coenzyme Q.sub.10 using ascorbic acid or a related compound thereof, operations are simplified and minimized, and thus reduced coenzyme Q.sub.10 of high quality is produced.

The present invention provides a stabilization method, a preservation method and the like method of reduced coenzyme Q.sub.10, which is useful as functional nutritive foods, specific health foods and the like. Furthermore, the present invention provides a method for efficiently obtaining reduced coenzyme Q.sub.10 of high quality and by a method suitable for a commercial production. It is possible to handle and stably preserve reduced coenzyme Q.sub.10 under a condition that oxidation by a molecular oxygen is inhibited by contacting reduced coenzyme Q.sub.10 with, an ascorbic acid and citric acid or a related compound thereof, and thus a stabilized composition is obtained. Moreover, reduced coenzyme Q.sub.10 is converted into a crystalline state in such a condition that the formation of oxidized coenzyme Q.sub.10 as a byproduct is minimized by crystallizing reduced coenzyme Q.sub.10 in the presence of ascorbic acid or a related compound thereof etc., and thus a reduced coenzyme Q.sub.10 crystal of high quality is produced. Furthermore, by successively crystallizing the generated reduced coenzyme Q.sub.10 in the presence of ascorbic acid or related compound thereof after reducing oxidized coenzyme Q.sub.10 to reduced coenzyme Q.sub.10 using ascorbic acid or a related compound thereof, operations are simplified and minimized, and thus reduced coenzyme Q.sub.10 of high quality is produced.