Study On The Synthesis Of Flame Retardant Tetrabromobisphenol-A And Premilinary Industrialization

Tetrabomobisphenol-A is a typical kind of brominated flame retardants with excellent property.Therefore,the research on the synthesis of tetrabromobisphenol-A is of great significance.In this thesis,tetrabromobisphenol-A was synthesized from bisphenol-A,bromine,hydrogen peroxide by in-situ bromination-oxidation with chlorobenzene as solvent.The synthetic process of tetrabromobisphenol-A was studied in batchwise reactor.The effect of the key factors on the reaction was studied with sulfuric acid as catalyst and the optimal conditions were as follows: the volume of chlorobenzene was 235 mL and the dosage of sulfuric acid was 1.0g when 45.7g bisphenol-A was fed.The molar ratio of the reactants n(bisphenol-A): n(bromine): n(hydrogen peroxide)was 1:2.1:2.2.The brominating temperature was 20? and the aging process was finished at 85? for 3 hours.The yield was not less than 93.7% based on bisphenol-A and the purity was not less than 99.5% under the optimal conditions while using recycled chlorobenzene.The yield increased by about 2% to 3% compared with that under the conditions without sulfuric acid as catalyst.Good results were also obtained when using other protonic acids such as hydrochloric acid,phosphoric acid,hydrobromic acid,p-toluene sulfonic acid and dodecyl benzene sulfonic acid in equimolar as catalysts under the same condition.The experimental results showed that dodecyl benzene sulfonic acid worked better in the catalyzing process than others.The authors proposed that it was the phase transfer catalytic ability of dodecyl benzene sulfonic acid made it an outstanding catalyst.And this method had not been reported in the previous literatures.On this basis,the synthetic process of tetrabromobisphenol-A with dodecyl benzene sulfonic acid as catalyst was studied and the optimal conditions were as follows: the volume of chlorobenzene was 235 mL and the dosage of dodecyl benzene sulfonic acid was 3.3g when 45.7g bisphenol-A was fed.The molar ratio of the reactants n(bisphenol-A): n(bromine): n(hydrogen peroxide)was 1:2.05:2.15.The brominating temperature was 20? and the aging process was finished at 85? for 1 hour.The yield was not less than 94.3% based on bisphenol-A and the purity was not less than 99.7% under the optimal conditions while using recycled chlorobenzene.What drew especial attention was that the aging time reduced from 3 hours to 1 hour and this should improve the production efficiency significantly.The process of industry scale-up experiment was investigated in 100 kg level preliminarily.The satisfactory results were obtained through appropriate adjustment and were of a certain industrial potentialities.The synthetic process of tetrabromobisphenol-A in continuous stirred tank reactor was rarely reported in literatures and there was no industrial practice in our country.The process was researched in laboratory scale and the optimal conditions obtained through single reactor were as follows: the molar ratio of the reactants n(bisphenol-A): n(bromine): n(hydrogen peroxide)was 1:2.05:2.1.The brominating temperature was 50? and the mean detention time was 40 min.Then the aging process was finished at 85? for 1 hour.The yield was not less than 91.4% based on bisphenol-A and the purity was not less than 99.7% while using recycled chlorobenzene,and the stability of product quality was able to ensured.The reaction conditions in continuous dual stirred tank reactors in series were farther optimized by single factor experiments and orthogonal experiments.The results were as follows: the molar ratio of the reactants n(bisphenol-A): n(bromine): n(hydrogen peroxide)was 1:2.05:2.1.The brominating temperature was 50? and the aging temperature was 80?.The total mean detention time was 80 min.The yield was not less than 95.0% based on bisphenol-A and the purity was not less than 99.8%.The stability of product quality was able to ensure and a reference for industrial continuous operation was provided.