Despite their atmospheric abundance, heterogeneous and multiphase reactions of carbonyl compounds are poorly understood. In this study, we investigate the surface adsorption and surface chemistry of methyl ethyl ketone (MEK), the second most abundant ketone in the atmosphere, with several mineral oxide surfaces including SiO 2 , α-Fe 2 O 3 and TiO 2 . In particular, the chemistry of MEK with these common components of mineral dust, under both dry and high relative humidity (RH%) conditions, has been investigated. Furthermore, reactions of adsorbed MEK with gas-phase NO 2 were also examined. We show that MEK molecularly and reversibly adsorbs on SiO 2 whereas irreversible adsorption occurs on both α-Fe 2 O 3 and TiO 2 surfaces, followed by the formation of higher molar mass species resulting from dimerization and oligomerization reactions. Isotope labeling experiments confirmed the incorporation of H atoms from surface hydroxyl groups and strongly adsorbed water into these oligomer products. Most interesting is that at 80% RH, oligomer formation on α-Fe 2 O 3 shifts toward a higher relative abundance of MEK tetramer relative to the dimer while on TiO 2 there was no change in product distribution. In the presence of gas-phase NO 2 , MEK undergoes degradation to formaldehyde and acetaldehyde, followed by the formation of aldol condensation products of these aldehydes on the α-Fe 2 O 3 surface. Overall, this study provides mechanistic insights on mineralogy-specific heterogeneous chemistry of a prevalent and atmospherically abundant ketone.
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Graphene oxide catalyzed ketone α-alkylation with alkenes: enhancement of graphene oxide activity by hydrogen bonding
Direct α-alkylation of carbonyl compounds represents a fundamental bond forming transformation in organic synthesis. We report the first ketone-alkylation using olefins and alcohols as simple alkylating agents catalyzed by graphene oxide. Extensive studies of the graphene surface suggest a pathway involving dual activation of both coupling partners. Notably, we show that polar functional groups have a stabilizing effect on the GO surface, which results in a net enhancement of the catalytic activity. The method represents the first alkylation of carbonyl compounds using graphenes, which opens the door for the development of an array of protocols for ketone functionalization employing common carbonyl building blocks and readily available graphenes.
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- Award ID(s):
- 1650766
- NSF-PAR ID:
- 10146144
- Date Published:
- Journal Name:
- Chemical Communications
- Volume:
- 55
- Issue:
- 37
- ISSN:
- 1359-7345
- Page Range / eLocation ID:
- 5379 to 5382
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Catalytic asymmetric α-alkylation of carbonyl compounds represents a long-standing challenge in synthetic organic chemistry. Herein, we advance a dual biocatalytic platform for the efficient asymmetric alkylation of α-keto acids. First, guided by our recently obtained crystal structures, we develop SgvMVAVas a general biocatalyst for the enantioselective methylation, ethylation, allylation and propargylation of a range of α-keto acids with total turnover numbers (TTNs) up to 4,600. Second, we mine a family of bacterial HMTs from
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c9cc02578b
