Research In The Reduction Of Aromatic Nitro Compounds In Alkaline Solution System

Aromatic nitro compounds have lively chemical properties, and can easily be reduced to azoxybenzenes. Predecessors had done a lot of research on the reduction of aromatic nitro compounds, their research mainly focused on the selection of reducing agents and reaction solutions. However, most of these reductions were reacted in toxic, volatile, flammable organic solvents, Moreover metal catalysts may be used, which resulted in the reaction wastes hard to be treated, and made reaction process complex. People have been focusing on the exploration of a simple, easy and environmentally friendly reduction method.Our group used β-CD, which is cheap and easy to get, in an alkaline aqueous solution to reduce aromatic nitro compounds, synthesized azoxybenzenes, made the reaction simply, efficiently and environmentally-friendly. The system was used to reduce Dichloronitrobenzenes, Trichloronitrobenzene, PCNB, Dibromonitrobenzene, etc. We analyzed experimental results, discussed the substituent effects on the reaction. Experimental results showed that the stronger the electron-withdrawing group is, the easier the reduction reacts. The more substituents on the benzene ring, will have more impact on the activity of the-NO2, the harder the reduction reacts.This paper further studied the reduction of the aromatic nitro compounds in glucose/NaOH water system, polyethylene glycol (PEG-600)/NaOH benzene system, ethanol/NaOH system, pentanol/NaOH system, as well as organic alkali DBU/β-CD system, etc. Contrasted to the experimental results of β-CD/NaOH aqueous solution system. We preliminary concluded that the reduction may be reacted in the synergistic effect of the alkoxy anion (RO-) and hydroxyl anion (OH-).