Research On Technical Conditions For Synthesis Of1-Chloroanthraquinone

1-Chloroanthraquinone is an important intermediate for preparation of anthraquinone series dyes and other chemical products. With the increasing applications of1-chloroanthraquinone in organic synthesis, the demand of1-chloroanthraquinone is increasing stably. Many ways are employed to the synthesis of1-chloroanthraquinone. Traditionally,1-chloroanthraquinone is prepared from anthraquinone by nitration, sulphonation and chlorination. The process is simple and the yield of the product is high, but during sulphonation, mercury is used as the targeting agent. Removal of mercury is high costly and serious environmental pollution may caused by mercury. Meanwhile, other methods of synthesis of1-chloroanthraquinone are unfavorable. Therefore, the introduction of new technology for synthesis of1-chloroanthraquinone is of practical significance. In this paper,3-chlorophthalic anhydride and benzene are used as raw materials, anhydrous AlCl3as catalyst to the synthesis of2-benzoyl-3-chlorobenzoic acid, which may further dehydrate into1-chloroanthraquinone. From the fundamental solution to the problem of mercury pollution, the production process meets the future development trend. The production process was studied in detail.(1) Differential scanning calorimetry (DSC), infrared spectroscopy (IR), mass spectrometry (MS), nuclear magnetic resonance NMR (HNMR) technology are used to the structure characterization of2-benzoyl-3-chloride benzoic acid and1-chloroanthraquinone. Through characterization, the products of2-benzoyl-3-chlorobenzoic acid and1-chloroanthraquinone were identified, which was the basis of optimization of the reaction. (2) During the synthesis of2-benzoyl-3-chlorobenzoic acid, we studied the influence of the hydrolysis solvent, feeding sequence, amount of catalyst, reaction time, reaction temperature and refluxing time on the reaction. The result shows that the optimum conditions are as following: chilled water as hydrolysis solvent, the catalyst anhydrous AlCl3added firstly and then3-chlorophthalic anhydride slowly, the amount of anhydrous AlCl3is3times of3-chlorophthalic anhydride, reaction time2hours, reaction temperature45℃, refluxing has no significant effect on the reaction. Under the optimum conditions, the final2-benzoyl-3-chlorobenzoic product could be obtained with purity of95.0%, the yield was95.2%.(3) During the synthesis of1-chloroanthraquinone, we studied the influence of cyclization reagent, the amount of acid, temperature and reaction time. The result showed optimum conditions as following:the appropriate reagents is oleum, the amount of oleum is3times of2-benzoyl-3-chlorobenzoic acid, reaction temperature120℃, reaction time2hours. Under the optimum conditions, the final1-chloroanthraquinone product could be obtained with purity of98.0%, the yield was95.2%.(4) Microwave synthesis of1-chloroanthraquinone was studied in the paper. The effct of technical conditions, including catalyst, the ratio of catalyst, reaction time and microwave power on the reaction was investigated. The results show that the optimal catalyst is AICl3/H2SO4, the mass ratio of AlCl3to H2SO4is0.11, reaction time is12minutes, and the microwave power is260W. Under the conditions above, the purity of1-chloroanthraquinone can rearch40%. As a result the microwave one-step synthesis of1-chloroanthraquinone is feasible.(5) Currently, The solubilities of2-benzoyl-3-chlorobenzoic acid have not been found and the solubilities of1-chloroanthraquinone is less. In this paper, the solubilities of2-benzoyl-3-chlorobenzoic acid and1-chloroanthraquinone in ethyl acetate, acetone, dioxane, toluene are studied, which is useful. The result shows that for2-benzoyl-3-chlorobenzoic acid, toluene>> dioxane> ethyl acetate> acetone; for1-chloroanthraquinone, ethyl acetate> toluene> dioxane> acetone. As the temperature increases, solubilities are all increasing.