{HEAD ~ The base} can be, for example, pyridine, dimethylaminopyridine, quinoline, {TAIL ~ trialkylamines}, and mixtures thereof 
be
{ HEAD ~ The base } can be , for example , pyridine , dimethylaminopyridine , quinoline , { TAIL ~ trialkylamines } , and mixtures thereof
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH