Since {HEAD ~ the presence} of H2 in the formate synthesis acts as {TAIL ~ a diluent}, diffusing out the H2 is not necessary 
acts as
Since { HEAD ~ the presence } of H2 in the formate synthesis acts as { TAIL ~ a diluent } , diffusing out the H2 is not necessary
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH