4.7: Nitration of Alkanes

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Another reaction of commercial importance is the nitration of alkanes to give nitroparaffins. Such reactions usually are carried out in the vapor phase at elevated temperatures using nitric acid (\(HNO_3\)) or nitrogen tetroxide (\(N_2O_4\)) as the nitrating agent:

R H plus H N O 3 goes to R N O 2 plus H 2 O at approximately 425 degrees.

All available evidence points to a radical mechanism for nitration, but many aspects of the reaction are not fully understood. Mixtures are obtained; nitration of propane gives not only 1- and 2-nitropropanes but nitroethane and nitromethane:

C H 3 C H 2 C H 3 plus H N O 3 goes to four different products. 25% 1-nitropropane, 40% 2-nitropropane, 10% nitroethane and 25% nitromethane.

In commercial practice, the yield and product distribution in nitration of alkanes is controlled as far as possible by the judicious addition of catalysts (e.g., oxygen and halogens), which are believed to raise the concentration of alkyl radicals. The products are separated from the mixtures by fractional distillation.

Contributors and Attributions

John D. Robert and Marjorie C. Caserio (1977) Basic Principles of Organic Chemistry, second edition. W. A. Benjamin, Inc. , Menlo Park, CA. ISBN 0-8053-8329-8. This content is copyrighted under the following conditions, "You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format."