Study On Synthesis Of 1-Bromoalkanes By Anti-Markovnikov Addition Reaction

1-Bromoalkanes is an important industrial solvent, chemical raw materials and fine chemical product. It has been served as organic intermediate, especially in medicine, pesticides, perfumes, dyes, surfactants, photographic materials and so on.1-Bromoalkanes was synthesized from terminal olefin and hydrogen bromide in the presence of a radical initiator by anti-Markovnikov addition reaction. From viewpoints of economy and environment, this method is accordance with "atom economy" and green chemistry concepts. Comparing to the traditional synthesis method, it had the advantages of cheap and readily available raw materials, simple production process, low production cost and environment-friendly. In this paper, the influence of various parameters including solvents, the amount of substrates, reaction time, reaction temperature for the synthesis of 1-bromooctane and 1-bromo-2-phenylethane were discussed. The reaction mechanism was also discussed.1-Bromooctane was synthesized from 1-octene and hydrogen bromide. The optimum synthesis conditions, without any solvent, material ratio was n1-octene:nHEBr=1:1.2, mBPO/m1-octene=0.15%, activation temperature was 30℃, reaction temperature was 20℃, reaction time was 1.5h and agitator speed was 450r/min-480r/min, were obtained by signal factor and orthogonal experiments. The product yield was determined by gas chromatography with normalization method. The conversion of 1-octene was more than 90%, and the yield of 1-bromooctane was more than 80%. Under the optimum reaction conditions, we performed larger scale experiments and the results were proved to be good repeatability and yield was above 80%.1-bromo-2-phenylethane was synthesized from styrene and hydrogen bromide. The optimum synthesis conditions, the material ratio was nstyrene:nHBr=1:1-1, mBPO/mstyrene=0.2%, the solvent was n-Heptane, Vstyrene:Vn-Heptane=1:2, the reaction temperature was 50℃, the reaction time was 2h and agitator speed was 450r/min-500r/min, were obtained by signal factor and orthogonal experiments. With gas chromatography method the product was quantitative analysised. The conversion of styrene was more than 90%, and the yield of 1-bromo-2-phenylethane was more than 80%. Under the optimum reaction conditions, we performed larger scale experiments and the results were proved to be good repeatability. Similarly, the yield of products was up to 80%.