Nuclear Spin Isomers of Ethylene: Enrichment by Chemical Synthesis and Application for NMR Signal Enhancement

Taking CH2CH2 for a spin: Enrichment of the nuclear spin isomers of ethylene was achieved by a catalytic reaction of acetylene with parahydrogen (see scheme). The spin isomers were used for NMR signal enhancement, both with and without subjecting them to a chemical reaction. The interconversion times of the nuclear spin isomers were evaluated at ambient pressure, thus revealing extremely long-lived spin states with lifetimes of (1000±400) s.