Preparation Of DSD Acid By Catalytic Transfer Reduction Using Aqueous Formate

4,4'-Diaminostilbene-2,2'-disulfonic acid is an exceedingly useful bifunctional synthetic intermediate and has been widely used in synthetic organic chemistry such as detergent, textile, plastic, photo and paper industry. In this paper, A new strategy for synthesis 4,4'-diaminostilbene-2,2'-disulfonic acid by Raney-Ni catalytic transfer reduction of 4,4'-dinirrostilbene-2,2'-disulfonic acid using sodium formate was investigated in the overall yield of higher than 96%. The new method overcomes disadvantages existing in the present methods. It is successful both in theory and in practice, and it enables the industrial productions of the tital compound. The main researches includs:1. Pd/C(5%)and Raney-Ni commonly used in industrial production are choosen as catalysts for catalytic transfer reduction by aqueous formate. The amount and activity were investigated to find the influence on the conversion and selectivity of DNS reduction. The results show that Pd/C(5%) has high catalytic activity, so that a large number of impurities(DADB) are contained in the product. However, passivated Raney-Ni could avoid the generation of the above impurities effectively. Thus, the selectivity of DNS increases greatly.2. Ascertainment of main factors for the synthetic of 4,4'-diaminostilbene-2,2'-disulfonic acid use orthogonal test. The experimental results show that, the optimum conditions are as follows: the passivated Raney-Ni is catalyst, the reaction temperature at 80℃, the amount of catalyst 0.10g(10% of DNS), the mole ratio 4,4'-dinitrostilbene-2,2'-disulfonic acid to sodium formate = 1:8.5 (molar ratio), and pH value is 5.1. Under the optimum conditions, the yield of DSD acid reaches 96%. So as to provide a new industrial production methods and experimental evidence.3. It is validated that the passivated Raney-Ni owns eminent seletivity, but its reuse capability is not so satisfactory. This paper analyzes the main reasons of catalyst deactivation is that the number of surface active sites reduce greatly.4. It is designed the wastewater treatment process of DSD preparation of sodium formate catalytic transfer reduction. Realize the recycling of formate and acetic acid through evaporation, sulfuric acidification, distillation and reduce the cost of the production. So as to prodive the theoretical evidence of follow-up experiment of wastewater treatment.