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Continuous Synthesis and Separation of p-Bromobenzyl Bromide Using Atom-Efficient Bromination of p-Bromotoluene without Any Organic Effluent: Potential for Green Industrial Practice
Organic Process Research & Development ( IF 3.1 ) Pub Date : 2021-08-25 , DOI: 10.1021/acs.oprd.1c00135 Sonam V. Sancheti 1 , Ganapati D. Yadav 1
Organic Process Research & Development ( IF 3.1 ) Pub Date : 2021-08-25 , DOI: 10.1021/acs.oprd.1c00135 Sonam V. Sancheti 1 , Ganapati D. Yadav 1
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This work focuses on the bromination of p-bromotoluene (PBT) using different brominating agents such as liquid Br2, NaBr–NaBrO3, NaBr–NaBrO3–NaCl, NaBr–H2O2, and HBr–H2O2. NaBr–NaBrO3–NaCl is an eco-friendly brominating agent obtained from a bromine recovery plant. Both NaBr–NaBrO3 and NaBr–NaBrO3–NaCl were found to be nonhazardous and efficient brominating agents. Pure NaBr–NaBrO3 resulted in the best PBT conversion with 79.7% Br atom efficiency in water and 98.2% average Br atom efficiency using dichloroethane as a solvent. Dichloroethane is de facto no longer used in the US and Europe and is not eco-friendly; the process with water as a solvent is the best. The substrate to active bromine molar ratio of 3:1 was found to be sufficient to get the maximum selectivity of p-bromobenzyl bromide (PBBB). The low-temperature crystallization method was used for separation cum purification of the product. Unreacted PBT was recycled along with the dibromo byproduct obtained. The dibromo product, which was built up gradually in the reaction mixture over 10 successive batches, was converted back into PBBB/PBT through NaBH4 treatment of the mother liquor. This continuous process is highly sustainable and produces zero organic waste, making it potentially attractive toward green industrial implementation.
中文翻译：
在没有任何有机废水的情况下，使用对溴甲苯的原子高效溴化连续合成和分离对溴苄基溴：绿色工业实践的潜力
此工作的重点的溴化p使用不同的溴化剂-bromotoluene（PBT），诸如液体溴2，溴化钠，NaBrO 3，溴化钠，NaBrO 3 -NaCl，溴化钠-H 2 ö 2，和HBr-H 2 ö 2。NaBr–NaBrO 3 –NaCl 是一种从溴回收厂获得的环保溴化剂。NaBr-NaBrO 3和NaBr-NaBrO 3 -NaCl 均被发现是无害且有效的溴化剂。纯 NaBr-NaBrO 3使用二氯乙烷作为溶剂时，PBT 转化率最高，溴原子效率为 79.7%，溴原子效率为 98.2%。美国和欧洲实际上已不再使用二氯乙烷，而且不环保；以水为溶剂的工艺最佳。发现底物与活性溴的摩尔比为 3:1 足以获得对溴苄基溴 (PBBB)的最大选择性。产品的分离提纯采用低温结晶法。未反应的 PBT 与获得的二溴副产物一起循环使用。通过 10 个连续批次在反应混合物中逐渐积累的二溴产物通过 NaBH 4转化回 PBBB/PBT母液的处理。这种连续过程是高度可持续的，产生零有机废物，使其对绿色工业实施具有潜在的吸引力。
更新日期：2021-09-17
中文翻译：
在没有任何有机废水的情况下，使用对溴甲苯的原子高效溴化连续合成和分离对溴苄基溴：绿色工业实践的潜力
此工作的重点的溴化p使用不同的溴化剂-bromotoluene（PBT），诸如液体溴2，溴化钠，NaBrO 3，溴化钠，NaBrO 3 -NaCl，溴化钠-H 2 ö 2，和HBr-H 2 ö 2。NaBr–NaBrO 3 –NaCl 是一种从溴回收厂获得的环保溴化剂。NaBr-NaBrO 3和NaBr-NaBrO 3 -NaCl 均被发现是无害且有效的溴化剂。纯 NaBr-NaBrO 3使用二氯乙烷作为溶剂时，PBT 转化率最高，溴原子效率为 79.7%，溴原子效率为 98.2%。美国和欧洲实际上已不再使用二氯乙烷，而且不环保；以水为溶剂的工艺最佳。发现底物与活性溴的摩尔比为 3:1 足以获得对溴苄基溴 (PBBB)的最大选择性。产品的分离提纯采用低温结晶法。未反应的 PBT 与获得的二溴副产物一起循环使用。通过 10 个连续批次在反应混合物中逐渐积累的二溴产物通过 NaBH 4转化回 PBBB/PBT母液的处理。这种连续过程是高度可持续的，产生零有机废物，使其对绿色工业实施具有潜在的吸引力。
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