Synthesis and electronic properties of π-extended flavins

Three flavins with extended aromatic systems were synthesized in moderate to good yields by condensation of the corresponding amines with violuric acid. The compounds are highly fluorescent, show quantum yields of up to 80% and redox mechanisms similar to riboflavin.

Degradation of a Phenolic β-O-4 Lignin Model Dimer by Electrochemically Mediated Delignification System with Violuric Acid

The β-O-4 type model compound guaiacylglycerol-β-guaiacyl ether was treated with a Violuric acid (VIO) mediated electrochemical delignification system. GC-MS analysis were used to investigate the changes of chemical structure of β-O-4 type model compound during reaction. Mechanism of this electrochemical delignification was also explored. Results indicated that the electrochemical oxidation by VIO as a mediator had strong oxidation capability on degradation of β-O-4 type model compound. After degradation, a series of aromatic compounds containing single benzene ring, furan compounds and aliphatic compounds with small molecule were produced. From their structures, the following reactions were caused by electrochemical oxidation: ether-bond cleavage, Cα-Cβ cleavage and benzene ring cleavage. Corrsequently, this work provides a comprehensive information on electrochemical oxidation delignification system that could be applied to industrial nonpollution bleaching.

Kinetics of Electrochemical Delignification Mediated with Violuric Acid

The violuric acid mediated chemical delignification system has a high delignification efficiency for pulp fibers and high delignification selectivity. The process conditions and effectiveness were carried out.The kinetics of electrochemical delignification has been investigated using the violuric acid (VIO) as the mediator. The reaction orders with respect to delignification, concentration of VIO and voltage of electrolytic cell were determined experimentally, which were dependent on the reaction conditions. The kinetic equation of electrochemical delignification and estimation function of kappa number were obtained respectively as follows: - dK/dt = A e-[VI1.031[2.197K6.25 , E=16.2KJ/mol, K(t)={2.89×10-7+5.25k [VI1.031[2.197t}-0.19.