noun
tautomerism
Chemistry term for the rapid interconversion of two isomers, typically involving the shift of a hydrogen atom and a double bond.
ケト-エノール互変異性は有機化学でよく見られる現象です。
Keto-enol tautomerism is a phenomenon often seen in organic chemistry.
異性体 (isomer) is a broader term for compounds with the same molecular formula but different structures, while 互変異性 specifically refers to tautomerism, a dynamic equilibrium between isomers.
Compound of 互変 (ごへん, 'mutual change') + 異性 (いせい, 'isomerism'), likely a calque from German Tautomerie or English tautomerism.