Question

In nucleophilic addition reaction only nucleophile is the caused for addition by attacking not positive part (like hydrogen) of the reagent?

why Hydrogen is not caused for addition reaction by attacking?

HINT: May be due to small size of Hydrogen.​

Answer 1

Answer:

The carbonyl compounds undergo nucleophilic addition reaction because oxygen is more electronegative than carbon. The addition of hydrogen halides is one of the easiest electrophilic addition reactions because it uses the simplest electrophile: the proton. Hydrogen halides provide both a electrophile (proton) and a nucleophile (halide). First, the electrophile will attack the double bond and take up a set of π electrons, attaching it to the molecule (1). This is basically the reverse of the last step in the E1 reaction (deprotonation step). The resulting molecule will have a single carbon- carbon bond with a positive charge on one of them (carbocation). The next step is when the nucleophile (halide) bonds to the carbocation, producing a new molecule with both the original hydrogen and halide attached to the organic reactant (2). The second step will only occur if a good nucleophile is used.