Q 14-14-43 E - Organic Chemistry (Mcmurry)

Question

Tires whose sidewalls are made of natural rubber tend to crack and

weather rapidly in areas around cities where high levels of ozone and

other industrial pollutants are found. Explain.

Step-by-Step Solution

Answer

Ozone causes oxidative cleavage of the double bond in rubber and breaks the polymer chain due to which cracks are occur to the tires whose sidewalls made of natural rubber.

Ozonolysis

Ozonolysis is a method of oxidatively cleaving alkenes or alkynes using ozone, a reactive allotrope of oxygen. The process allows for carbon-carbon double or triple bonds to be replaced by double bonds with oxygen.

Oxidation of alkenes with the help of ozone can give alcohols, aldehydes, and ketones.

This is also known as oxidative cleavage reaction, a reaction in which carbon-carbon bond is cleaved, with simultaneous oxidation of carbon that had formed the carbon-carbon bond. 

Oxidative cleavage reaction

Ozone is a very reactive allotrope of oxygen. The reaction of ozone with alkenes and alkynes causes the oxidative cleaving of alkene or alkyne. The carbon-carbon triple bonds are replaced with carbon-oxygen double bonds, giving the required carbonyl product as shown below:

                          Formation of carbonyl products

Oxidative cleavage of double bond in rubber

Ozone causes oxidative cleavage of the double bond in rubber and breaks the polymer chain due to which cracks are occur to the tires whose sidewalls made of natural rubber.

                                        Oxidative cleavage