The catalyst may be any of {HEAD ~ the dialkyl} substituted {TAIL ~ aromatic amines}, preferably N,N dimethylparatoluidine or N,N diisopropylparatoluidine 
The catalyst may be any of { HEAD ~ the dialkyl } substituted { TAIL ~ aromatic amines } , preferably N , N dimethylparatoluidine or N , N diisopropylparatoluidine
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH