A simple ligand- and additive-free gold catalyst system that enables the CO-mediated reductive coupling of nitroarenes has been identified.
已经确定了一种简单的无需配体和添加剂的金催化剂体系,它能实现硝基芳烃的由一氧化碳介导的还原偶联反应。
The activating effect of the phenylazo substituent in electrophilic substitution has been examined. The rates and partial rate factors for chlorination of azobenzene with molecular chlorine and protonated chlorine acetate have been determined relative to benzene. Whereas the chlorine acetate reaction proceeds readily (relative rate 4900) there is virtually no activation to chlorination by molecular chlorine. Complexes between azobenzene and bromine were, however, isolated and chatacterized. Their formation implies that during molecular halogenation reactions the electrophile is essentially unavailable. The relative chlorination rates for azobenzene and azoxybenzene have also been established: the phenylazo group is more activating towards protonated chlorine acetate whereas azoxybenzene (which does not complex with halogens) is the more reactive with molecular chlorine. The chlorination results confirm the versatility of the phenylazo group which is the first substituent for which kinetic data have been obtained quantifying activation of aromatic electrophilic, radical and nucleophilic substitution.