Hydrogen-bonding and protonation effects on the formation of charge transfer complex between para-benzoquinone and 2,6-dimethoxy phenol

Formation of CT complex of series of quinines of increasing basicity (chloranil to duroquinone) were checked systematically in methylenechloride with different aromatic donors in presence of hydroxylic additives of increasing hydrogen-bonding power (tetra-butyl-alcohol to hexafluoro-2-propanol) or acidity. The effect of the basic additives of increasing basicity (pyridine to 4-N,N-dimethylaminopyridine) was also observed. The formation constant (KCT) of CT complex between para-benzoquinone and 2,6-dimthoxyphenol was enhanced approximately 50 times by TFA and approximately two times by HFIPA due to protonation and strong hydrogen-bonding interaction of BQ with TFA and HPIPA, respectively. Similarly, KCT increased approximately six times by DMAPy due to hydrogen-bonding with DMOPh.