Glass surface as strong base, ‘green’ heterogeneous catalyst and degradation reagent

Li, Yangjie; Huang, Kuan-Gen; Morato, Nicolás M.; Cooks, R. Graham

doi:10.1039/d1sc02708e

Cited by 21 publications

(9 citation statements)

References 54 publications

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“…Glass surfaces can act as strong bases and degradation reagents. [52] Experiments using a Teflon container with a similar volume of trapped oxygen from the air above the mixture did not result in significant differences in yields, as the data in Table 4 illustrate. Under these experimental conditions, many products were observed with styrene as substrate, none for 1-pentene, and indene afforded 7(2)% of indanone (Table 7).…”

Section: Discussionmentioning

confidence: 81%

Free‐radical catalyzed oxidation reactions with cyclohexene and cyclooctene with peroxides as initiators

Luck

Newberry

2022

J of Physical Organic Chem

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The free‐radical oxidation reaction of cyclohexene is accomplished at 80°C in a 10:1 1,2‐dichloroethane:acetonitrile mixture under an air atmosphere using 0.05 molar equivalents of either tBuOOH or H2O2 and results in a 33.7% conversion yielding 23.7% 2‐cyclohexen‐1‐one, 8.0% 2‐cyclohexen‐1‐ol, and 2.0% cyclohexene oxide. With cyclooctene under similar conditions, a 42.3% conversion is obtained, 40.3% cyclooctene oxide, 0.4% of 1,2‐cyclooctanediol, and 1.2% of 2‐cycloocten‐1‐one. The reaction is dependent on dioxygen as reduced yields are obtained under a nitrogen atmosphere. It is initiated best with H2O2 and tBuOOH and does not work with ammonium persulfate as a radical initiator. This free‐radical reaction was not useful for three other alkenes tested under similar reaction conditions. Transition states and activation energies were calculated with the APFD functional and 6‐311 + G(d) basis set for possible reaction pathways involving radicals produced from the homolysis of the peroxide OO bond followed by abstraction of an alkyl H atom, forming a cyclic alkene radical. This can react rapidly with dioxygen forming a cyclic‐alkene peroxide radical. This intermediate may result in ketone products via a unimolecular pathway, whereas the formation of epoxides requires a bimolecular route. This was confirmed experimentally as lower epoxide yields for reaction with cyclooctene were obtained if the reaction solution was diluted. It is suggested that reactions involving cyclohexene where similar yields of products were obtained may also involve free‐radical pathways.

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Section: Discussionmentioning

confidence: 81%

Free‐radical catalyzed oxidation reactions with cyclohexene and cyclooctene with peroxides as initiators

Luck

Newberry

2022

J of Physical Organic Chem

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“…The compatibility of DESI-MS with automated high-throughput screening enables chemical analysis at throughputs better than one sample per second using high-density arrays (50 nL samples, up to 6,144 samples per array) ( Morato et al, 2021 ). Applications include screening of organic reactions ( Wleklinski et al, 2018 ; Jaman et al, 2019 , 2020 ; Loren et al, 2019 ; Biyani et al, 2020 ; Ewan et al, 2020 ; Sobreira et al, 2020 ; Li et al, 2021a ; Morato et al, 2021 ), label-free enzymatic assays ( Morato et al, 2020 ; Kulathunga et al, 2022 ), and the generation of spectral libraries ( Le et al, 2021 ). Here, we take advantage of high-throughput DESI to investigate adduct formation by water radical cations in a large compound set.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets

et al. 2022

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Spontaneous oxidation of compounds containing diverse X=Y moieties (e.g., sulfonamides, ketones, esters, sulfones) occurs readily in organic-solvent microdroplets. This surprising phenomenon is proposed to be driven by the generation of an intermediate species [M+H2O]+·: a covalent adduct of water radical cation (H2O+·) with the reactant molecule (M). The adduct is observed in the positive ion mass spectrum while its formation in the interfacial region of the microdroplet (i.e., at the air-droplet interface) is indicated by the strong dependence of the oxidation product formation on the spray distance (which reflects the droplet size and consequently the surface-to-volume ratio) and the solvent composition. Importantly, based on the screening of a ca. 21,000-compound library and the detailed consideration of six functional groups, the formation of a molecular adduct with the water radical cation is a significant route to ionization in positive ion mode electrospray, where it is favored in those compounds with X=Y moieties which lack basic groups. A set of model monofunctional systems was studied and in one case, benzyl benzoate, evidence was found for oxidation driven by hydroxyl radical adduct formation followed by protonation in addition to the dominant water radical cation addition process. Significant implications of molecular ionization by water radical cations for oxidation processes in atmospheric aerosols, analytical mass spectrometry and small-scale synthesis are noted.

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“…This review collects important results from the scientic literature or the past century which shows that the surface of regular laboratory glassware should not be considered inert during chemical reactions. It is evident that the vast majority of reported vessel effects concern organouorine chemistry, but a signicant number of reports involving Brønsted acid/base catalysis (most notably in recent reports by Cooks and coworkers 117,118 ) should inspire our peers to probe the impact of vessel material as a standard variable during reaction development. In fact, we believe that the ramications of vessel effects throughout the scientic literature are more far-reaching than has previously been reported, since vessel effects are typically not probed during reaction development or optimization.…”

Section: Discussionmentioning

confidence: 99%

“…The ability for glass to act as a strong base heterogeneous catalyst has recently been further studied by Cooks and co-workers ( Scheme 14 ). 117 In a systematic study using ESI-MS and high-throughput experimentation, it became evident that various base-catalyzed reactions were catalyzed at the solid/solution interface. The reaction types found to be catalyzed included eliminations, condensations, oxidations and solvolysis reactions, which clearly indicates the broad scope of reactions potentially influenced by the choice of reaction vessel.…”

Section: Glass Surface As a Heterogeneous Brønsted Base-catalystmentioning

confidence: 99%

Vessel effects in organic chemical reactions; a century-old, overlooked phenomenon

Nielsen

Pedersen

2022

Chem. Sci.

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Glass surface as strong base, ‘green’ heterogeneous catalyst and degradation reagent

Abstract: Systematic screening of accelerated chemical reactions at solid/solution interfaces has been carried out in high-throughput fashion using desorption electrospray ionization mass spectrometry and it provides evidence that glass surfaces accelerate...

Cited by 21 publications

References 54 publications

Free‐radical catalyzed oxidation reactions with cyclohexene and cyclooctene with peroxides as initiators

Free‐radical catalyzed oxidation reactions with cyclohexene and cyclooctene with peroxides as initiators

Spontaneous Water Radical Cation Oxidation at Double Bonds in Microdroplets

Vessel effects in organic chemical reactions; a century-old, overlooked phenomenon

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