( It ( ( is ( ( ( ( an alkene-alcohol ) , ) hence ) ( the ( name enol ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (NP (NP (DT an) (NN alkene-alcohol)) (, ,) (RB hence) (NP (DT the) (NN name) (NN enol)))) (. .)))
It is an alkene-alcohol, hence the name enol.
(ROOT (S (NP (NNS Alkenes)) (VP (VBP are) (VP (VBN formed) (PP (IN from) (NP (NP (DT an) (NN alcohol)) (SBAR (WHNP (WDT that)) (S (VP (VBZ loses) (NP (NN water))))))))) (. .)))