( ( When ( ( an alcohol ) ( is ( heated ( in ( ( the presence ) ( of ( a ( strong acid ) ) ) ) ) ) ) ) ) ( , ( ( the ( major product ) ) ( ( is ( ( ( an alkene ) or ) ( ( a mixture ) ( of alkenes ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT an) (NN alcohol)) (VP (VBZ is) (VP (VBN heated) (PP (IN in) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (DT a) (JJ strong) (NN acid))))))))) (, ,) (NP (DT the) (JJ major) (NN product)) (VP (VBZ is) (NP (NP (DT an) (NN alkene)) (CC or) (NP (NP (DT a) (NN mixture)) (PP (IN of) (NP (NNS alkenes)))))) (. .)))
When an alcohol is heated in the presence of a strong acid, the major product is an alkene or a mixture of alkenes.
(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))))))))) (. .)))