Study On The Synthetic Process Of Reactive Yellow M-5G

Dye is a substance that can color all kinds of textile fiber,and play an vital role in enriching people's material and cultural life.With the increasingly growing demand for natural fiber fabrics,including cotton,linen and silk,the reactive deys have been extensively investigated by researchers.Reactive Yellow M-5G,an M-type dual reactive dye with an azo group,simultaneously pocessesses the advantages of vinyl sulfone active group and monochloro-sym-triazine active group.As an important yellow dye,reactive Yellow M-5G has extensive applications and excellent dyeing property.According to the synthesis characteristics of azo dyes,active yellow M-5G is generally synthesized by the conventional stirred tank reactor(STR).Due to the large volume of STR,it is difficult to achieve uniform mixng performance in different areas in STR,which casues some serious probelems,such unbalanced material ratios and insufficient performance of heat and mass transfer.These will ultimately result in decomposition of diazonium salts and generation of side reactions,and further affect the yield of products as well as differences in intensity and shade in virous batches of dyes.High-gravity reactor,rotating packed bed(RPB),can achieve the rapid mixng performance and greatly intensify the mass transfer process between materials through the high-gravity invironment created by high-speed rotating packing.Therefore,we introduced RPB into the synthesis process of azo dyes in this paper.In this paper,the synthetic process of reactive yellow M-5G was invstigated in STR and RPB,respectively.UV spectrometer(UV),liquid chromatograph(LC-MS)and infrared spectrometer(IR)were used for qualitative analysis and characterization of structure of products.A quantitative analysis method based on spectrophotometry was established.The main conclusions are as follows:(1)Single factor experiments were adopted to determine the optimal route for synthesis of reactive yellow M-5G in STR.The optimal conditions of diazo-reaction are:time of 40 min,temperature of 5?,para-ester:sodium nitrite:hydrochloric acid(molar ratio)=1:1.05:3,stirring speed of 700 rpm,and the yield of product can reach 73.6%.The optimal conditions of coupling reaction are:time of 40 min,temperature of 5 ?,para-ester:coupling component(molar ratio)=1:1,pH = 6,stirring speed of 600 rpm,and the yield of product can reach 73.8%.(2)The optimum reaction conditions for the synthesis of reactive yellow M-5G in combined STR-RPB reactor were investigated.The optimal conditions of diazo-reaction are:time of 30 min,feeding time of 2min,temperature of 10?,rotor speed of 1120 rpm,and the yield of product can reach 74.6%.The optimal conditions of coupling reaction are:time of 30 min,temperature of 5 ?,pH = 7,rotor speed of 1400 rpm,and the yield of product can reach 74.9%.(3)The optimal reaction conditions for the synthesis of reactive yellow M-5G in RPB reactor by means of material circulation were investigated.The optimal conditions of diazo-reaction are:time of 30 min,material circulation flow rate of 270 ml/min,rotor speed of 1200 rpm,and the yield of product can reach 75.8%.The optimal conditions of coupling reaction are:time of 25 min,material circulation flow rate of 270ml/min,rotor speed of 800 rpm,and the yield of product can reach 76.2%.Compared to STR,the reaction time in the RPB can be reduced by 1/5 to 1/4,and the yield of reactive yellow M-5G can also be increased to a certain extent.Given a comprehensive consideration of various factors,it is of value to adopt RPB as synthesis reactor for reactive yellow M-5G in industry.