( ( A ( -RRB- Substitution ) ) ( ( ( does not ) ( occur ( when ( ( the ( carbon atom ) ) ( is ( doubly ( bonded ( to ( a ( nitrogen atom ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NNP -RRB-) (NNP Substitution)) (VP (VBZ does) (RB not) (VP (VB occur) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN carbon) (NN atom)) (VP (VBZ is) (ADJP (RB doubly) (JJ bonded) (PP (TO to) (NP (DT a) (NN nitrogen) (NN atom))))))))) (. .)))
A) Substitution does not occur when the carbon atom is doubly bonded to a nitrogen atom.
(ROOT (S (NP (NNS Amines)) (VP (VBP are) (VP (VBN classified) (PP (VBG according) (PP (TO to) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NN carbon) (NNS atoms)) (VP (VBG bonded) (ADVP (RB directly)) (PP (TO to) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (JJ nitrogen) (NN atom))))))))))) (. .)))