I'm working on the project in which p-toluenesulfonyl chloride (TsCl) is the main material to synthesis the mono-tosyl substituted. The TsCl in my lab is produce in China and has been opened nearly 8 months, I have purify it by recrystallize in Chloroform/Hexane or CCl4 but the results still not good (poor yield of substitution) so I wonder about it's purity, is it was being degraded?
Is there any analytical method to test the purity of TsCl?