1
|
Udagawa T, Murphy RB, Darwish TA, Tachikawa M, Mori S. H/D Isotope Effects in Keto-Enol Tautomerism of β-Dicarbonyl Compounds —Importance of Nuclear Quantum Effects of Hydrogen Nuclei—. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Taro Udagawa
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Rhys B. Murphy
- Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights NSW 2234, Australia
| | - Tamim A. Darwish
- Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights NSW 2234, Australia
| | - Masanori Tachikawa
- Graduate School of NanobioScience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Seiji Mori
- Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| |
Collapse
|
2
|
Murphy RB, Staton J, Rawal A, Darwish TA. The effect of deuteration on the keto-enol equilibrium and photostability of the sunscreen agent avobenzone. Photochem Photobiol Sci 2020; 19:1410-1422. [PMID: 32966538 DOI: 10.1039/d0pp00265h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The remarkable properties of deuterium have led to many exciting and favourable results in enhancing material properties, for applications in the physical, medical, and biological sciences. Deuterated isotopologues of avobenzone, a sunscreen active ingredient, were synthesised to examine for any changes to the equilibrium between the diketone and enol isomers, as well as their UV photostability and photoprotective properties. Prior to UV irradiation, deuteration of the diketone methylene/enol moiety (i.e. avobenzone-d2) led to an increase in the % diketone compared to non-deuterated, determined by 1H NMR experiments in CDCl3 and C6D12. This can be rationalised from two angles; mechanistically by a deuterium kinetic isotope effect for the CH vs. CD abstraction step during tautomerisation from the diketone to the enol, and a weaker chelating hydrogen bond for the enol when deuterated allowing increased equilibration to the diketone. Avobenzone-d2 was further examined by solid state 13C NMR. The higher % diketone for avobenzone-d2 was postulated to favour increased photodegradation by a non-reversible pathway. This was investigated by UV irradiation of the avobenzone isotopologues in C6D12, both in real time in situ within the NMR by fibre optic cable as well as ex situ using sunlight. An increase in the relative amount of photoproducts for avobenzone-d2 compared to non-deuterated was observed by 1H NMR upon UV irradiation ex situ. Overall, the study demonstrates that deuteration can be applied to alter complex equilibria, and has potential to be manifested as changes to the properties and behaviour of materials.
Collapse
Affiliation(s)
- Rhys B Murphy
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.
| | - John Staton
- Eurofins Dermatest, 20 King Street, Rockdale, New South Wales 2216, Australia
| | - Aditya Rawal
- Nuclear Magnetic Resonance Facility, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia
| | - Tamim A Darwish
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.
| |
Collapse
|
3
|
Anania M, Jašíková L, Zelenka J, Shcherbachenko E, Jašík J, Roithová J. Monoaurated vs. diaurated intermediates: causality or independence? Chem Sci 2019; 11:980-988. [PMID: 34084352 PMCID: PMC8146099 DOI: 10.1039/c9sc05662a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Diaurated intermediates of gold-catalysed reactions have been a long-standing subject of debate. Although diaurated complexes were regarded as a drain of active monoaurated intermediates in catalytic cycles, they were also identified as the products of gold-gold cooperation in dual-activation reactions. This study shows investigation of intermediates in water addition to alkynes catalysed by [(IPr)Au(CH3CN)(BF4)]. Electrospray ionisation mass spectrometry (ESI-MS) allowed us to detect both monoaurated and diaurated complexes in this reaction. Infrared photodissociation spectra of the trapped complexes show that the structure of the intermediates corresponds to α-gold ketone intermediates protonated or aurated at the oxygen atom. Delayed reactant labelling experiments provided the half life of the intermediates in reaction of 1-phenylpropyne (∼7 min) and the kinetic isotope effects for hydrogen introduction to the carbon atom (KIE ∼ 4-6) and for the protodeauration (KIE ∼ 2). The results suggest that the ESI-MS detected monoaurated and diaurated complexes report on species with a very similar or the same kinetics in solution. Kinetic analysis of the overall reaction showed that the reaction rate is first-order dependent on the concentration of the gold catalyst. Finally, all results are consistent with the reaction mechanism proceeding via monoaurated neutral α-gold ketone intermediates only.
Collapse
Affiliation(s)
- Mariarosa Anania
- Department of Organic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 12843 Prague 2 Czech Republic
| | - Lucie Jašíková
- Department of Organic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 12843 Prague 2 Czech Republic
| | - Jan Zelenka
- Institute for Molecules and Materials, Radboud University Heyendaalseweg 135 6525 AJ Nijmegen Netherlands
| | - Elena Shcherbachenko
- Department of Organic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 12843 Prague 2 Czech Republic
| | - Juraj Jašík
- Department of Organic Chemistry, Faculty of Science, Charles University Hlavova 2030/8 12843 Prague 2 Czech Republic
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University Heyendaalseweg 135 6525 AJ Nijmegen Netherlands
| |
Collapse
|
4
|
Jensen PR, Taarning E, Meier S. Probing the Lewis Acid Catalyzed Acyclic Pathway of Carbohydrate Conversion in Methanol by
In Situ
NMR. ChemCatChem 2019. [DOI: 10.1002/cctc.201901241] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Pernille Rose Jensen
- Department of Health TechnologyTechnical University of Denmark Ørsteds Plads 349 2800 Kgs. Lyngby Denmark
| | - Esben Taarning
- Haldor Topsøe A/S Haldor Topsøes Allé 1 2800 Kgs. Lyngby Denmark
| | - Sebastian Meier
- Department of ChemistryTechnical University of Denmark Kemitorvet Bygning 207 2800 Kgs. Lyngby Denmark
| |
Collapse
|
5
|
Affiliation(s)
- Charles L. Perrin
- Department of Chemistry & Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, United States
| | - Kuei-Lin Chang
- Department of Chemistry & Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, United States
| |
Collapse
|
6
|
Giovani S, Singh R, Fasan R. Efficient conversion of primary azides to aldehydes catalyzed by active site variants of myoglobin. Chem Sci 2015; 7:234-239. [PMID: 26900445 PMCID: PMC4754990 DOI: 10.1039/c5sc02857d] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/28/2015] [Indexed: 12/19/2022] Open
Abstract
The oxidation of primary azides to aldehydes constitutes a convenient but underdeveloped transformation for which no efficient methods are available. Here, we demonstrate that engineered variants of the hemoprotein myoglobin can catalyze this transformation with high efficiency (up to 8,500 turnovers) and selectivity across a range of structurally diverse aryl-substituted primary azides. Mutagenesis of the 'distal' histidine residue was particularly effective in enhancing the azide oxidation reactivity of myoglobin, enabling these reactions to proceed in good to excellent yields (37-89%) and to be carried out at a synthetically useful scale. Kinetic isotope effect, isotope labeling, and substrate binding experiments support a mechanism involving heme-catalyzed decomposition of the organic azide followed by alpha hydrogen deprotonation to generate an aldimine which, upon hydrolysis, releases the aldehyde product. This work provides the first example of a biocatalytic azide-to-aldehyde conversion and expands the range of non-native chemical transformations accessible through hemoprotein-mediated catalysis.
Collapse
Affiliation(s)
- Simone Giovani
- Department of Chemistry , University of Rochester , 120 Trustee Rd , Rochester , New York 14627 , USA .
| | - Ritesh Singh
- Department of Chemistry , University of Rochester , 120 Trustee Rd , Rochester , New York 14627 , USA .
| | - Rudi Fasan
- Department of Chemistry , University of Rochester , 120 Trustee Rd , Rochester , New York 14627 , USA .
| |
Collapse
|
7
|
Lounasvuori MM, Rosillo-Lopez M, Salzmann CG, Caruana DJ, Holt KB. The influence of acidic edge groups on the electrochemical performance of graphene nanoflakes. J Electroanal Chem (Lausanne) 2015. [DOI: 10.1016/j.jelechem.2015.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
8
|
A theoretical investigation on the proton transfer tautomerization mechanisms of 2-thioxanthine within microsolvent and long range solvent. J Mol Model 2013; 19:3279-305. [DOI: 10.1007/s00894-013-1858-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 04/17/2013] [Indexed: 11/26/2022]
|
9
|
Abstract
Linear relations of the form DeltapK = pK(D) - pK(H) = a + b pK(H) relating ionization constants of acids in light and heavy water must have the same slope b for any kind of acid unless the previously unconsidered charge type is important or this equation is not valid.
Collapse
|
10
|
|
11
|
The Brønsted α and the Primary Hydrogen Isotope Effect. A Test of the Marcus Theory. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470143698.ch17] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|
12
|
Claramunt R, López C, Lott S, Santa María M, Alkorta I, Elguero J. Solid-State NMR Study of the Tautomerism of Acetylacetone Included in a Host Matrix. Helv Chim Acta 2005. [DOI: 10.1002/hlca.200590148] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
13
|
Iglesias E. Tautomerization of 2-acetylcyclohexanone. 1. Characterization of keto-enol/enolate equilibria and reaction rates in water. J Org Chem 2003; 68:2680-8. [PMID: 12662038 DOI: 10.1021/jo026629x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The keto-enol tautomerism of 2-acetylcyclohexanone (ACHE) was studied in water under different experimental conditions. By contrast with other previously studied beta-diketones, the keto-enol interconversion in the ACHE system is a slow process. Under equilibrium conditions, the analysis of the absorbance readings of ACHE aqueous solutions yielded more than 40% of enol content at 25 degrees C; nevertheless, in aprotic solvents such as dioxane, ACHE is almost completely enolized. In alkaline medium, the enolate ion is the only existing species; the study of the effect of pH on the UV-absorption spectrum of ACHE yielded a value of 9.85 for the overall pK(a) of ACHE. Under nonequilibrium conditions, the keto-enol tautomerization was studied in water. Several factors affecting the reaction have been investigated, which include H(+)-catalysis, ionic strength effect, buffer catalysis, deuterium isotope effects, temperature effect, or solvent effects.
Collapse
Affiliation(s)
- Emilia Iglesias
- Dpto de Química Física e E. Q. I. Facultad de Ciencias, Universidad de La Coruña, 15071-La Coruña, Spain.
| |
Collapse
|
14
|
|
15
|
Francalanci F, Gardano A, Abis L, Fiorani T, Foà M. Cobalt-catalyzed carbonylation of optically active and α-deuterated phenethyl halides. J Organomet Chem 1983. [DOI: 10.1016/0022-328x(83)80224-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
16
|
Abstract
The ionization kinetics of carbon acids are slow relative to those of classical acids and bases. Phenindione (2-phenyl-1,3-indandione) is a 1,3-diketone carbon acid of macroscopic experimental pKa 4.09 at 25 degrees and ionic strength 0.1. The ionization kinetics of phenindione were determined at an ionic strength of 0.1 and 25 degrees using stopped-flow spectrophotometry and a pH jump technique. A log k'obs-pH profile for the approach to the ionization equilibrium was determined, and a mechanism consistent with the profile was postulated. The percent enol versus diketo form of phenindione and the pKaenol and pKadiketo were calculated from the kinetic data. Phenindione acid deprotonation kinetics by various oxygen and nitrogen bases suggested that, with bases of pKa 4.7--8.5 and in the pH 5--8.5 range, the acidic phenindione proton as approximately 45% transferred in the rate-determining transition state.
Collapse
|
17
|
Chapter 2 Proton Transfer to and from Carbon. ACTA ACUST UNITED AC 1977. [DOI: 10.1016/s0069-8040(08)70090-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
|
18
|
|
19
|
Pitman IH, Higuchi T, Alton M, Wiley R. Deuterium isotope effects on degradation of hydrocortisone in aqueous solution. J Pharm Sci 1972; 61:918-20. [PMID: 5046110 DOI: 10.1002/jps.2600610619] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
20
|
Developments in the study of A-SE2 Reactions in Aqueous Solution. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 1968. [DOI: 10.1016/s0065-3160(08)60254-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|