Study On Reduction Of Aromatic Nitro Compounds With Hydrazine Hydrate And Its Application In Synthesis Of Active Dye Intermediates

Currently the main problem of the commonly used type of vinyl sulfone reactive dyes is its low fixation rate in the application. Therefore development of new reactive dye intermediates and new reactive dyes in order to improve the color fixation rate is very necessary.During the manufacture of reactive dye intermediates, the reduction of aromatic nitro compounds to the reaction of aromatic amine is very important. Reduction methods on the industry at present are iron powder reduction, alkali sulphide reduction, and catalytic hydrogenation, etc. With the price of hydrazine hydrate gradually reduced, using hydrazine hydrate as reductant for reduction of aromatic nitro compounds will become an environment-friendly and simple way. Development of cheap, safe, high catalytic activity, recyclable catalyst is the key point of the present study.In this dissertation three new vinyl sulfone type reactive dye intermediates (Ⅰ, Ⅱ, Ⅲ) were designed and synthesized. The structures of the synthesized compounds were characterized by1H NMR,13C NMR, MS and IR spectra. Reaction conditions in the synthetic procedures were explored and the optimal synthetic conditions were found, and the exploration to hydrazine hydrate reduction method of the catalyst has been carried on. The dissertation mainly contains the following aspects:1. Synthesis of intermediate I. Acid amide product2was obtained as main product by the reaction between p-nitrophenyl sulfonyl chloride and the thioether product1synthesized from β-mercaptoethanol and2-chloroethylamine hydrochloride. Sulfone compound3was obtained by oxidation of the thioether2with hydrogen peroxide. Amine product4was obtained from reduction of the nitro group in product3with hydrazine hydrate. Compound5(intermediate I) was obtained by esterification of4with25%fuming sulfuric acid.2. Synthesis of intermediate II. Acid amide product7was obtained as main product by the reaction between p-nitrophenyl sulfonyl chloride and the thioether product6synthesized from β-mercaptoethanol and3-bromopropylamine hydrobromide. Sulfone compound8was obtained by oxidation of the thioether7with hydrogen peroxide. Amine product9(intermediate II) was obtained from reduction of the nitro group in product8with hydrogen and hydrazine hydrate.3. Exploration of reducing condition of sulfone compounds for the preparation of amino compound9, by using different kinds of hydrazine hydrate as catalyst for reduction of aromatic nitro compounds.4. Synthesis of intermediate III. Acid amide product10was obtained as main product by the reaction between p-nitrobenzoyl chloride and the thioether product6. Sulfone compound11was obtained by oxidation of the thioether10with hydrogen peroxide. Amine product12(intermediate III) was obtained from reduction of the nitro group in product11with hydrogen and hydrazine hydrate.