Which two compouunds form Methyl Thiobutanoate(CH3CH2CH2COSCH3) in esterification?
Actually I just don't know where does the "S" come from?? Does it come from the alcohol group or the acid group?
It does not matter S come from
You should write an esterification reaction, ie
acid + "alcohol"
ther just two possibilities - one of two reagents should contain S