- Synthesis and antimicrobial activity of nitrobenzyl-oxy-phenol derivatives
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Two hydroquinone derivatives were prepared and their antimicrobial activity evaluated. Their minimum inhibitory concentrations (MICs) were determined using a broth dilution method. Gentamycin and ciprofloxacin were used as reference antibiotics. The antimicrobial activity of 4-(benzyloxy)phenol (monobenzone) was also evaluated based on its structural similarity to the new compounds; activity was comparable to that of 3,5-dimethyl-4-((4-nitrobenzyl)oxy)phenol (4a). 2,3,5-Trimethyl-4-((4-nitrobenzyl)oxy)phenol (4b) exhibited the best antibacterial activity against both clinical isolates and type strain of Moraxella catarrhalis (M. catarrhalis), with a MIC value of 11 μM, comparable to ciprofloxacin 9 μM.
- Mohamed, Malik Suliman,Maki, Toshihide,Shah, Mohammad Monir,Ichinose, Yoshio
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- Efficient synthesis of vitamin e intermediate by lipase-catalyzed regioselective transesterification
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Trimethylhydroquinone-1-monoacetate (TMHQ-1-MA) is a valuable synthetic intermediate for vitamin E acetate. Immobilized Lipozyme RM IM from Mucor miehei was shown to be the best biocatalyst for the production of TMHQ-1-MA through regioselective transesterification between trimethylhydroquinone diacetate (TMHQ-DA) and alcohol. The effects of lipase-catalyzed reaction conditions including solvent, acyl receptor, substrate mole ratio, reaction temperature and agitation speed were investigated. The optimum conditions for Lipozyme RM IM catalyzed regioselective transesterification were achieved at a substrate mole ratio of 1:1, an agitation of 200 rpm at 50 °C in MTBE/n-hexane (3:7). Under the above conditions, Lipozyme RM IM exhibited high substrate tolerance (substrate concentrations of 1.06 M). Recycling experiments demonstrated that Lipozyme RM IM was quite steady under the reaction conditions. The analysis of kinetic experiment showed that the enzymatic reaction obeys the Ping-Pong bi-bi mechanism with n-butanol inhibition.
- Wei, Chun,Fu, Xian-Feng,Wang, Zhao,Yu, Xin-Jun,Zhang, Yin-Jun,Zheng, Jian-Yong
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- Choice of Manganese(III) Complexes for the Synthesis of 4,4'-Biphenyldiols and 4,4'-Diphenoquinones
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2,6-Disubstituted phenols are oxidized with tris(2,4-pentanedionato)manganese(III), , in glacial acetic acid to give the corresponding 4,4'-biphenyldiols in high yields, whereas similar reactions using manganase(III) acetate, , instead of quantitatively yield the corresponding 4,4'-diphenoquinones.Cross-coupling reactions of 2,6-di-t-butylphenol and other substituted phenols afford the corresponding cross-coupled 4,4'-biphenyldiols and 4,4'-diphenoquinones together with oxidation products derived from them starting phenols themselves.The advantageous use of and Mn(OAc)3> in the ubiqitous phenol coupling reaction is discussed.
- Nishino, Hiroshi,Nobuyuki, Itoh,Nagashima, Makiko,Kurosawa, Kazu
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p. 620 - 622
(2007/10/02)
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