Without these extractive distillation agents, {TAIL ~ no improvement} above {HEAD ~ the azeotrope composition} will occur in a rectification column 
Without these extractive distillation agents , { TAIL ~ no improvement } above { HEAD ~ the azeotrope composition } will occur in a rectification column
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH