三溴化硼二氯溶液或者纯的三溴化硼都可以，一般是两当量以上吧，不是很危险，就是打开时冒烟很厉害，小心操作没有问题，在-50 度以下加入，室温反应很快的

这个反应后处理很重要，生成的硼化合物需要根据其性质想办法除去才行

在惰性气体氛围和0°C下，将三溴化硼的二氯甲烷（或二氯乙烷-78度）溶液缓慢滴加到原料的二氯甲烷溶液中发生脱甲基化反应。滴加完毕后，回复室温搅拌几小时。反应完后，在冰浴下加水处理，经萃取、干燥、过滤、浓缩就行了，原料与三溴化硼的加料摩尔比一般为3/1~1/1

这是我做过的BBr3（溶液）脱甲基的步骤
To a solution of 6-methoxyquinoline-4-carbaldehyde (3.6 g, 19.23 mmol) in dry Dichloromethane (DCM) (150 mL)  was added tribromoborane (19.27 g, 77 mmol) dropwise under nitrogen at -78oC. After addition, the reaction solution was stirred at room temperature for overnight. Then the mixture was cooled to -78oC, and then water was added dropwise to it until no gas was liberated. The reaction mixture was then extracted with CH2Cl2, then EA. The organic layer was washed with brine, dried over Na2SO4 and concentrated to obtain a crude product 6-hydroxyquinoline-4-carbaldehyde (1.8g, 9.44 mmol, 49.1 % yield).
后处理也可以这样：反应结束后，直接倒入冰水中，然后旋蒸除去DCM，之后用NaHCO3调碱性至9-10，析出黄色固体，抽滤，固体就是产物，