11. Radical Reactions

What is the percentage yield of the major product?

What is the percentage yield of the major product?

The chlorination of pentane gives a mixture of three monochlorinated products.

b. Predict the ratios in which these monochlorination products will be formed, remembering that a chlorine atom abstracts a secondary hydrogen about 4.5 times as fast as it abstracts a primary hydrogen.

Given the ratio of products obtained in the bromination of propane, calculate the relative reactivity of a 1° C–H bond to a 2° C–H bond under these conditions.

A chemist wanted to determine experimentally the relative ease of removing a hydrogen atom from a tertiary, a secondary, and a primary carbon by a chlorine radical. He allowed 2-methylbutane to undergo chlorination at 300 °C and obtained as products 36% 1-chloro-2-methylbutane, 18% 2-chloro-2-methylbutane, 28% 2-chloro-3-methylbutane, and 18% 1-chloro-3-methylbutane. What values did he obtain for the relative ease of removing a hydrogen atom from tertiary, secondary, and primary hydrogen carbons by a chlorine radical under the conditions of his experiment?

When 2-methylpropane is monochlorinated in the presence of light at room temperature, 36% of the product is 2-chloro-2-methylpropane and 64% is 1-chloro-2-methylpropane. From these data, calculate how much easier it is to remove a hydrogen atom from a tertiary carbon than from a primary carbon under these conditions.

Would chlorination or bromination be a better way to make 1-halo-2,2-dimethylpropane?

Would chlorination or bromination produce a greater yield of 2-halo-2,3-dimethylbutane?

Would chlorination or bromination produce a greater yield of 1-halo-2,3-dimethylbutane?

What is the anticipated percent yield of the major product?

Which product would be obtained in greatest yield? Explain.

The following are all substitution reactions, two of which we study in later chapters. With no knowledge of mechanism, what would you expect the ratio of products to be for each reaction, based on a random statistical distribution?

(a) Replacing a hydrogen (H) with chlorine (Cl):

What would be the product ratio in the chlorination of propane if all the hydrogens were abstracted at equal rates?

Suppose you intend to synthesize the secondary alkyl halide from each reaction shown.

(a) What is the atom economy of each reaction?

(c) Which reaction would you consider greener? Why?

Suppose you intend to synthesize the secondary alkyl halide from each reaction shown.

(b) What is the E-factor, effective mass yield, and process mass intensity?

(c) Which reaction would you consider greener? Why?