The temperature and pressure are not critical, but {HEAD ~ the reaction} is preferably carried out at {TAIL ~ reflux temperature} and atmospheric pressure 
The temperature and pressure are not critical , but { HEAD ~ the reaction } is preferably carried out at { TAIL ~ reflux temperature } and atmospheric pressure
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH