During the syntheses, {HEAD ~ the beads} may be washed free of {TAIL ~ any excess reagents} or by products before proceeding to the next reaction 
washed free of
During the syntheses , { HEAD ~ the beads } may be washed free of { TAIL ~ any excess reagents } or by products before proceeding to the next reaction
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH