( He ( ( wants ( ( ( a reaction ) , ) ( ( positive or ) negative ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBZ wants) (NP (NP (DT a) (NN reaction)) (, ,) (ADJP (JJ positive) (CC or) (JJ negative)))) (. .)))
He wants a reaction, positive or negative.
(ROOT (S (S (VP (VBZ Is) (NP (NP (DT the) (NN heat)) (PP (IN of) (NP (NP (NN reaction)) (PP (IN for) (NP (DT an) (JJ endothermic) (NN reaction)))))))) (VP (VBZ is) (ADJP (JJ positive))) (. .)))