{TAIL ~ each R17} is independently {HEAD ~ hydrogen}, saturated hydrocarbyl or substituted saturated hydrocarbyl; and 
{ TAIL ~ each R17 } is independently { HEAD ~ hydrogen } , saturated hydrocarbyl or substituted saturated hydrocarbyl ; and
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH