( ( ( Substitution reaction ) ( -LRB- ( ( also ( known ( as ( ( ( single ( displacement reaction ) ) or ) ( single ( replacement reaction ) ) ) ) ) ) -RRB- ) ) ) ( ( is ( ( a ( chemical reaction ) ) ( ( during which ) ( ( ( one ( functional group ) ) ( in ( a ( chemical compound ) ) ) ) ( is ( replaced ( by ( another ( functional group ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN Substitution) (NN reaction)) (PRN (-LRB- -LRB-) (VP (ADVP (RB also)) (VBN known) (PP (IN as) (NP (NP (JJ single) (NN displacement) (NN reaction)) (CC or) (NP (JJ single) (NN replacement) (NN reaction))))) (-RRB- -RRB-))) (VP (VBZ is) (NP (NP (DT a) (JJ chemical) (NN reaction)) (SBAR (WHPP (IN during) (WHNP (WDT which))) (S (NP (NP (CD one) (JJ functional) (NN group)) (PP (IN in) (NP (DT a) (NN chemical) (NN compound)))) (VP (VBZ is) (VP (VBN replaced) (PP (IN by) (NP (DT another) (JJ functional) (NN group))))))))) (. .)))
Substitution reaction (also known as single displacement reaction or single replacement reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group.
(ROOT (S (ADVP (RB Replace)) (NP (NP (DT another)) (PP (IN in) (NP (DT a) (NN molecule)))) (VP (VBZ happens) (PP (TO to) (NP (NNS atoms))) (PP (IN during) (NP (DT a) (NN substitution) (NN reaction)))) (. .)))
Replace another in a molecule happens to atoms during a substitution reaction.