Reaction temperature is usually 0° to 100° C., {HEAD ~ preferably 20°} to {TAIL ~ 80° C} 
to
Reaction temperature is usually 0 ° to 100 ° C. , { HEAD ~ preferably 20 ° } to { TAIL ~ 80 ° C }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL