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