Synthetic Procedure Of 4,4'-Bis(chloromethyl)biphenyl

Fluorescent whitening agent plays an important role in our lives. Fluorescent Brightener usually is a complex organic compound used as a fluorescent dye or white dye. It is characterized by the incident light to generate fluorescence excitation, so that the stained material was similar to the fluorite sparkling effect to the naked eye to see the material is white, to the effect of whitening. Fluorescent whitening agent has been used in the paper industry and.4,4'-dichloro-biphenyl is a key synthetic intermediate for fluorescent whitening agent 2,2'-([1,1'-Biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis-benzenesulfonic acid. The purity of 4,4'-dichloro-biphenyl directly affects the efficiency of fluorescent whitening agent. So it is far-reaching significance for design and optimize the preparation procedure of 4,4'-dichloro-biphenyl in both academic research and industrial application. Based on previous research, we designed and innovated an excellent procedure for synthesis of 4,4'-dichloro-biphenyl with high purity in high yield.This thesis mainly contains the following contents:(1) Concerning for the synthesis of 4,4'-dichloromethyl-biphenyl was reviewed in detail. And their advantages and disadvantages of relevant synthetic methods were analyzed.(2) Based on the methodologies reported in literatures for the synthesis of 4, 4'-dichloro-biphenyl, we studied the novel synthetic method for 4,4'-dichloro-biphenyl in detail from the reaction conditions to the feed ratio of raw materials and got an ideal result.(3)In continuation of our research, according to the industrialization requirement, we found that additional raw material paraformaldehyde and phase transfer catalyst used in concentrated hydrochloric acid-formic acid reaction system can improve the yield and purity of 4,4'-dichloro-biphenyl. We get the best laboratory technique are: the molar ratio feed of biphenyl and paraformaldehyde is 1:22; catalyst zinc chloride is 1.7 times the amount for the biphenyl (mole ratio) and use the equivalent of the phase-transfer catalyst; formic acid and concentrated hydrochloric acid used as the solvent; the quality of water of the reaction solvent is 4-5 times as quality as the zinc chloride; the reaction temperature is 90°C and the reaction time is 17 h; during all the reaction process, hydrogen chloride gas is always keeped; in the late reaction to the reaction solution about 1/15 of the initial paraformaldehyde was added to finish the reaction compleltely. Our researching results had obvious advantages than previous synthetic route which has good prospects for industrial applications.(4) After we got the lab scale technical procedure, we investigated its application in industrialization. After modification of the conditions, we got the industrial production technology.