Preferably the alkylene group has {TAIL ~ one to ten carbon atoms}, {HEAD ~ preferably one to six carbon atoms}, and preferably is a methylene group, —CH2— 
Preferably the alkylene group has { TAIL ~ one to ten carbon atoms } , { HEAD ~ preferably one to six carbon atoms } , and preferably is a methylene group , — CH2 —
OTH OTH OTH OTH OTH TAIL TAIL 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 OTH OTH OTH OTH