Problem 22P
When n-heptane burns in a gasoline engine, the combustion process takes place too quickly. The explosive detonation makes a noise called knocking. When 2,2,4-trimethylpentane (isooctane) is burned, combustion takes place in a slower, more controlled manner. Combustion is a free-radical chain reaction, and its rate depends on the reactivity of the free-radical intermediates. Explain why isooctane has less tendency to knock than does n-heptane.
Alkoxy radicals are generally more stable than alkyl radicals. Write an equation showing an alkyl free radical (from burning gasoline) abstracting a hydrogen atom from tert-butyl alcohol, \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}\). Explain why tert-butyl alcohol works as an antiknock additive for gasoline.
Use the information in Table 4-2 (page 143) to explain why toluene \(\left(\mathrm{PhCH}_{3}\right)\) has a very high octane rating of 111. Write an equation to show how toluene reacts with an alkyl free radical to give a relatively stable radical.
Equation Transcription:
Text Transcription:
(CH_3)_3COH
(PhCH_3)
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Chapter 4, Problem 22P is Solved
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