Copper-induced activation of dioxygen and hydrogen peroxide for the dehydrogenation and oxygenation of organic substrates /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | In acetonitrile/pyridine bis(bipyridine)copper(I) [Cu^I(bpy)2[^+1]] catalyzes the reaction of HOOH with hydrocarbons. With one-to-one combinations the primary product is the alcohol of the hydrocarbon substrate, via a Fenton process, and the reactivity correlates with their C-H bond-dissociation energies (ΔH[DBE])- The presence of H2O does not affect the reactivity. When dioxygen (O2) is present (or with a 20-fold excess of HOOH) the system selectively ketonizes methylenic carbon centers. In acetonitrile/pyridine bis(bipyridine)copper(H) [Cu^II(bpy)2[^2+]] is an effective catalyst for the activation of HOOH or O2 to dehydrogenate amines. This system also demethylates N-methyl anilines via a dioxygenase mechanism. The primary product of benzylamine is benzaldehyde [PhCH(O)], which reacts with excess substrate to form a Schiff base product. The catalyst demethylates N-methyl anilines through the dioxygenation of the methyl carbon center and a subsequent decarboxylation. The reaction efficiency relative to HOOH for benzylamine is 36%. The product yields with O2 are normally lower than those for HOOH. However, for N,N-dimethylbenzylamine, the product yield with O2 is almost two times that which results with HOOH. The combination of bis(bypyridine)copper(II) [Cu^II(bpy)2[^2+]] and two equivalents of base [HO- or HOC(O)O ] with excess alcohol (e.g., PhCH2OH) in an O2 -saturated acetonitrile solution results in the rapid, catalytic transformation of the alcohol to its aldehyde (or ketone for secondary alcohol). The rate of the process is first-order each in substrate, catalyst, and O2 concentrations with an apparent rate constant, k, for PhCH2OH of 62 M^-2s^-1. Aliphatic primary alcohols react 4-20 times slower, and a-allylic alcohols react 2-4 times slower than PhCH2OH. Secondary alcohols react 2-10 times slower than primary alcohols. Substitution on the benzene ring of benzyl alcohol (nucleophilic or electrophilic) has a negative effect on the yield of the benzaldehyde. In the absence of alcohol the catalyst initiates the auto-oxygenation of aldehydes to carboxylic acids. |
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| Item Description: | Vita. "Major subject: Chemistry." |
| Physical Description: | xii, 89 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |