Question

Propene □(→┴HBr) A □(→┴(i) Mg/ether) B
In the above sequence of reactions, B is
(a) propane (b) butane
(c) propene (d) ethane

Answer 1

Let us answer it

Explanation:

Let us complete it first

Propene + HBr --------> A ---------> B

                                        Mg/ether

The complete reaction is :

CH₃CHCH₂  + HBr ---> CH₃CH(Br)CH₃             ---Mg---->  CH₃CH(MgBr)CH₂

  propene                        (2 Bromo propane )    dry ether

CH₃CH(MgBr)CH₂  ----------> CH₃CH₂CH₃

                               (H₂O)        Propane

The propene on reacting with hydrogen bromide obeys Markov's rule and forms 2 bromopropane .This on reacting with Mg in presence of dry ether forms grignard reagent which further on hydrolysis forms propane .

So, the answer is : (a) propane