Question

Determine the type of each of the reactions:

Short answer

The reaction a is an elimination reaction while b is an addition reaction.

Step-by-step solution

Introduction

Since, the given compounds are organic compounds, the reactions are organic reactions. Basically, organic reactions can be of many types like addition reaction, elimination reaction, substitution reaction, photochemical reactions, pericyclic reactions, rearrangement reactions.

  Reaction a)

In the first reaction given, it is clear that there is an elimination of H and Br followed by the generation of a double bond, so the reaction is an elimination reaction. An elimination reaction is a reaction in which two substituents are removed from the molecule or substrate in one or two steps. If the elimination is a one step process it is known as E2 elimination while, if it is a two step process, it is known as E1 elimination.

  Reaction b)

The second reaction is catalytic hydrogenation of pentene which is an electrophilic addition reaction which converts an unsaturated pentene to a saturated pentane.

Electrophilic Addition reactions are addition reactions where a pi bond is broken to generate two new sigma bonds.