Explain why the rate of bromination of methane decreases if HBr is added to the reaction mixture.

Predict the major products of the following alkane halogenation reactions. [The number of products shown ignores the formation of racemic mixtures.]

(c)

Other molecules can be used as initiators in radical reactions. One such molecule is 2, 2'-azobisisobutyronitrile (AIBN). Show an arrow-pushing mechanism that rationalizes the formation of the following radical species. What are the driving forces of this reaction?

Cyclizations can be carried out under radical conditions involving Bu₃SnH and a catalytic amount of AIBN. Suggest a mechanism for this reaction. [Pay close attention to the bonds formed and broken in developing your mechanism. It may be helpful to number the carbons.]

What alkane, with molecular formula C₅H₁₂, forms only one monochlorinated product when it is heated with Cl₂?

How many alkyl halides are obtained from monochlorination of the alkanes in Problem 4 if stereoisomers are included?

c.

How many monochlorination products would be obtained if all stereoisomers are included?

What is the major product obtained from treating an excess of each of the following compounds with Cl₂ in the presence of ultraviolet light at room temperature? Disregard stereoisomers.

a.

In the presence of an acid catalyst, acetaldehyde forms a trimer known as paraldehyde. Because it induces sleep when it is administered to animals in large doses, paraldehyde is used as a sedative or hypnotic. Propose a mechanism for the formation of paraldehyde.