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One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light

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Science  19 Dec 2014:
Vol. 346, Issue 6216, pp. 1495-1498
DOI: 10.1126/science.1259684

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Abstract

Nitric acid oxidation of cyclohexane accounts for ~95% of the worldwide adipic acid production and is also responsible for ~5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N2O). Here we report a N2O-free process for adipic acid synthesis. Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid.

Using ozone below may conserve it above

The accumulation of laughing gas in the atmosphere isn't a laughing matter: Nitrous oxide (N2O) is a powerful greenhouse gas and a depleter of ozone. The manufacture of nylon releases substantial N2O as a byproduct during preparation of the precursor adipic acid. Hwang and Sagadevan now demonstrate an alternate route to adipic acid that involves treating cyclohexane with ozone under concurrent ultraviolet irradiation, generating no N2O. Thus, ironically, the application of ozone as a chemical reagent could ultimately help conserve its concentration in the atmosphere.

Science, this issue p. 1495

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