{TAIL ~ an alkyl group} having {HEAD ~ from 1 to 6 carbon atoms} and which is straight or branched, 
{ TAIL ~ an alkyl group } having { HEAD ~ from 1 to 6 carbon atoms } and which is straight or branched ,
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH