Problem 15
What effect does branching of an alkane chain has on its boiling point?
Problem 16
Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism.
Problem 17
Write down the products of ozonolysis of 1,2 -dimethylbenzene (o-xylene). How does the result support Kekulé structure for benzene?
Problem 18
Arrange benzene, \(n\) -hexane and ethyne in decreasing order of acidic behaviour. Also give reason for this behaviour.
Problem 19
Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?
Problem 21
Write structures of all the alkenes which on hydrogenation give 2-methylbutane.
Problem 22
Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, \(\mathrm{E}\) (a) Chlorobenzene, 2,4-dinitrochlorobenzene, \(p\) -nitrochlorobenzene (b) Toluene, \(p-\mathrm{H}_{3} \mathrm{C}-\mathrm{C}_{6} \mathrm{H}_{4}-\mathrm{NO}_{2}, p-\mathrm{O}_{2} \mathrm{~N}-\mathrm{C}_{6} \mathrm{H}_{4}-\mathrm{NO}_{2}\).
Problem 23
Out of benzene, \(m\) -dinitrobenzene and toluene which will undergo nitration most easily and why?
Problem 24
Suggest the name of a Lewis acid other than anhydrous aluminium chloride which can be used during ethylation of benzene.
Problem 25
Why is Wurtz reaction not preferred for the preparation of alkanes containing odd number of carbon atoms? Illustrate your answer by taking one example.
