{TAIL ~ The solvent} can be selected from ketones, esters, cyclic ethers and other kinds of {HEAD ~ polar solvents} and may be a mixed solvent 
{ TAIL ~ The solvent } can be selected from ketones , esters , cyclic ethers and other kinds of { HEAD ~ polar solvents } and may be a mixed solvent
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH