Chapter 6
Q. 6.1
Identifying Electrophiles and Nucleophiles
Which of the following species is likely to behave as a nucleophile and which as an electrophile?
(a) {NO_2}^{+} (b) CN^{-} (c) CH_3NH_2 (d) (CH_3)_3S^+
S t r a t e g y
A nucleophile has an electron-rich site, either because it is negatively charged or because it has a functional group containing an atom that has a lone pair of electrons. An electrophile has an electron-poor site, either because it is positively charged or because it has a functional group containing an atom that is positively polarized.
Step-by-Step
Verified Solution
(a) {NO_2}^+ (nitronium ion) is likely to be an electrophile because it is positively charged.
(b) :C≡N^- (cyanide ion) is likely to be a nucleophile because it is negatively charged.
(c) CH_3NH_2 (methylamine) might be either a nucleophile or an electrophile depending on the circumstances. The lone pair of electrons on the nitrogen atom makes methylamine a potential nucleophile, while positively polarized N–H hydrogens make methylamine a potential acid (electrophile).
(d) (CH_3)_3S^+ (trimethylsulfonium ion) is likely to be an electrophile because it is positively charged.