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漆酶的催化氧化反应是一个包括酶反应和非酶反应的复杂过程。一般认为,在漆酶催化下,底物酚先转变为酚氧游离基;生成的酚氧游离基中间体进行非酶反应,或歧化成醌,或迅速重排为芳基碳游离基后引起其他游离基反应,如偶联、聚合等。由于一般酚氧游离基很活泼,并迅速重排为芳基碳游离基,所以至今已研究过的酚类底物,用漆酶催化氧化的结果,最终都几乎是生成以碳-碳偶联为主的复杂氧化产物,生成醌的可能性极少。事买上,利用大基团的空间效应,可以使酚氧游离基变得很稳定。因此,在适当位置具有较大基团的酚类底物,在漆酶催化氧化下,有可能阻止酚氧游离基的重排,使最终产物停留在醌的阶段。我们用3,5-二叔丁基-1,2-苯二酚(DBC)为底物探讨了这种可能性,获得了几乎定量转变成3,5-二叔丁基-1,2-苯醌(DBQ)的满意结果(式1)。
The catalytic oxidation of laccase is a complex process that includes both enzymatic and non-enzymatic reactions. It is generally believed that under the catalysis of laccase, the phenolic precursor of the substrate is first converted to the phenolic oxygen radical; the resulting phenolic oxygen free radical intermediate undergoes non-enzymatic reaction or disproportionation to quinone or rapid rearrangement to the aryl carbon radical Other free radical reactions, such as coupling, polymerization and so on. Since the general phenolic oxygen radicals are very reactive and are rapidly rearranged to aryl carbon radicals, the phenolic substrates studied to date, the result of catalyzed oxidation with laccase, eventually result in almost carbon-carbon coupling Based on the complex oxidation products, the possibility of generating quinones rarely. Things to buy, the use of the space effect of large groups, can make phenolic oxygen free radicals become very stable. Thus, phenolic substrates with larger groups in the proper positions, with the laccase catalytic oxidation, are likely to prevent the rearrangement of the phenolic oxygen radicals leaving the final product in the quinone stage. We explored this possibility with 3,5-di-tert-butyl-1,2-dihydroxybenzene (DBC) as a substrate and obtained an almost quantitative conversion to 3,5-di-tert-butyl- Satisfactory results of benzoquinone (DBQ) (Formula 1).