Heteropolyvanadates as catalysts for oxygenation of 3,5-Di-t-butylcatechol

Tatsuno, Yoshitaka; Nakamura, Chitose; Saito, Taro

doi:10.1016/0304-5102(87)85039-3

Cited by 23 publications

(9 citation statements)

References 17 publications

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“…Entries I − IV and VII , Table , show that the vanadium-containing polyoxoanions, with or without iron, are the best catalyst precursors; only vanadium is required for dioxygenase catalysis, however (i.e., the non-vanadium containing polyoxoanions in entries VIII and IX are inactive, as is Fe II (CH 3 CN) 6 2+ alone, entry XI ; the control in entry XII demonstrates the expected lack of reaction in the absence of any catalyst). Entry V shows that the single vanadium-containing polyoxoanion is inactive, while entry VI reveals that V IV (O)(acac) 2 is active as previously reported. ,11a A significant finding, however, is that V IV (O)(acac) 2 reproducibly (two tries) fails to evolve into a high-activity catalyst when sufficient DTBC is available for 100 000 total turnovers (TTOs), conditions where the polyoxoanion III , for example, evolves (in six independent experiments, see Table S13 of the Supporting Information) into a highly active, long-lived catalyst. As mentioned in the Introduction, the adamantane oxygenation catalyst developed by Neumann, entry X , is inactive for the dioxygenase catalysis reported herein over a period of 25 h, and even though a control showed that the Neumann catalyst was active in our hands, and as reported, for adamantane oxidation (11% 1-admantanol and 4% 2-adamantone in 24 h at 85 °C, 1 atm O 2 and in 1,2-dichloroethane solvent, comparable to the literature's ∼10% 1-admantanol after 18 h at 80 °C) 12c.…”

Section: Resultssupporting

confidence: 73%

An All-Inorganic, Polyoxometalate-Based Catechol Dioxygenase That Exhibits >100 000 Catalytic Turnovers

1999

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Following a critical analysis of the dioxygenase literature and injection of the insights therein into the development of new dioxygenase catalysts, two new, of four total exemplary, polyoxoanion precatalysts have been synthesized, characterized, and then discovered to exhibit record catalytic lifetime 3,5-di-tertbutylcatechol (DTBC; 1) dioxygenase activity using molecular oxygen as the terminal oxidant. A total of 24 additional polyoxoanion and other precatalysts have also been surveyed for their DTBC dioxygenase activity. The four exemplary precatalyst complexes are the trivanadium(V)-containing, orange-red parent polyoxoanions (n-Bu 4 N) 7 [SiW 9 V 3 O 40 ], I, and (n-Bu 4 N) 9 [P 2 W 15 V 3 O 62 ], II, and their previously unknown polyoxoanionsupported, dark green iron complexes (n-Bu 4 N) 5 [(CH 3 CN) x Fe‚SiW 9 V 3 O 40 ], III, and (n-Bu 4 N) 5 [(CH 3 CN) x Fe‚ P 2 W 15 V 3 O 62 ], IV. Careful, high (95 ( 5%) mass balance studies are reported, studies rare in the dioxygenase literature, but studies made possible in the case of I-IV by their high activity and long lifetimes which yielded sizable amounts of isolable, and thus unequivocally characterizable, products (the characterization of products 2, 3, 4, and 6 includes single-crystal X-ray crystallography structures): 3,5-di-tert-butyl-1-oxacyclohepta-3,5diene-2,7-dione (muconic acid anhydride), 2; 4,6-di-tert-butyl-2H-pyran-2-one, 3; a new, previously unidentified product (once misidentified in the literature), spiro[1,4-benzodioxin-2(3H), 2′-[2H]pyran]-3-one, 4′,6,6′,8tetrakis(1,1-dimethylethyl), 4; 3,5-di-tert-butyl-5-(carboxymethyl)-2-furanone, 5; and the autoxidation product, 3,5-di-tert-butyl-1,2-benzoquinone, 6. Quantitative yields for each of the above products are also reported. Solvent effects on the dioxygenase reaction are evaluated by survey studies in 5 solvents; the highest yields are observed in non-coordinating solvents such as 1,2-dichloroethane. Oxygen uptake studies are reported; the results confirm the 1 O 2 :1 DTBC stoichiometry which defines a catechol dioxygenase and address, for the first time, the details of how this ∼1:1 stoichiometry actually arises from the linear combination of the individual stoichiometries of the five, formally parallel, major reactions yielding the five major products. Initial kinetic studies are also reported; the O 2 uptake kinetics reveal a novel product and catalyst evolution mechanism consisting of an A f B induction period, followed by an A + B f 2 B autocatalytic step for complexes I and III, where A ) O 2 and B is a product of the DTBC plus O 2 reaction. Catalyst lifetime experiments with (n-Bu 4 N) 5 [(CH 3 CN) x Fe‚SiW 9 V 3 O 40 ], III, as a prototype precatalyst reveal a DTBC dioxygenase catalytic lifetime of >100 000 total catalytic turnovers (TTOs), a record compared to any reported dioxygenase, man-made or enzymic. A Summary and Conclusions section is presented, as is a list of the needed additional, in-progress, kinetic, mechanistic, and catalyst isolation and characterization studies. The l...

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Section: Resultssupporting

confidence: 73%

An All-Inorganic, Polyoxometalate-Based Catechol Dioxygenase That Exhibits >100 000 Catalytic Turnovers

1999

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“… a Inactive vanadium-containing precatalysts omitted from the above table, but listed here for the sake of completeness are [V(salen)(cat)]·0.1CH 2 Cl 2 and [V(salen)(4-Bcat)]·H 2 O; Na[VO(DBcat) 2 ] and Na 2 [VO(OCH 3 )(DBcat) 2 ]; VO(acac)(cat) and VO(acac)(3-Bcat); [VW 5 O 19 3- ]; VO(NTA); and [SiW 11 VO 40 5- ] …”

Section: Resultsmentioning

confidence: 99%

“…Isolation and characterization of the actual catalyst, if possible, would of course provide direct evidence of the identity of the true catalyst, although the obvious caveat here is that good catalysts are often metastable transients that are not readily isolable (see “Halpern's Rules” as detailed elsewhere). Nevertheless, it was important to attempt to isolate an active catalyst (or even a deactivated form of the active catalyst) from the vanadium-containing polyoxometalate precatalysts, especially in light of earlier indications that this might be possible. , However, in the end, we were not able to isolate analytically pure catalysts from these particular studies, so that we turned to the use of in situ spectroscopic studies (vide infra). Details of the attempted isolation studies are in the Supporting Information, along with figures showing IR, negative ion ESI-MS, or EPR of the resultant materials (Figures S11−S14).…”

Section: Methodsmentioning

confidence: 99%

“…Tatsuno and co-workers reported catechol oxygenation catalysis using the heteropolyvanadates, PV 14 O 42 9- , MnV 13 O 38 7- , and NiV 13 O 38 7- . Isolation of the reaction intermediate afforded a blue compound, tentatively assigned as the dimer complex “[V(DBSQ)(DBCatH)] 2 ” by elemental analysis, IR, EPR results, and a cryoscopic measurement of the approximate molecular weight (DBCatH ≡ monoprotonated di- tert -butylcatecholate anion) …”

Section: Introductionmentioning

confidence: 99%

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Vanadium-Based, Extended Catalytic Lifetime Catechol Dioxygenases: Evidence for a Common Catalyst

Yin

Finke

2005

J. Am. Chem. Soc.

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In 1999, a catechol dioxygenase derived from a V-polyoxometalate was reported which was able to perform a record >100 000 total turnovers of 3,5-di-tert-butylcatechol oxygenation using O2 as the oxidant (Weiner, H.; Finke, R. G. J. Am. Chem. Soc. 1999, 121, 9831). An important goal is to better understand this and other vanadium-based catechol dioxygenases. Scrutiny of 11 literature reports of vanadium-based catechol dioxygenases yielded the insight that they all proceed with closely similar selectivities. This, in turn, led to a "common catalyst hypothesis" for the broad range of vanadium based catechol dioxygenase precatalysts presently known. The following three classes of V-based compounds, 10 complexes total, have been explored to test the common catalyst hypothesis: (i) six vanadium-based polyoxometalate precatalysts, (n-Bu4N)4H5PV14O42, (n-Bu4N)7SiW9V3O40, (n-Bu4N)5[(CH3CN)(x)Fe(II).SiW9V3O40], (n-Bu4N)9P2W15V3O62, (n-Bu4N)5Na2[(CH3CN)(x)Fe(II).P2W15V3O62], and (n-Bu4N)4H2-gamma-SiW10V2O40; (ii) three vanadium catecholate complexes, [V(V)O(DBSQ)(DTBC)]2, [Et3NH]2[V(IV)O(DBTC)2].2CH3OH, and [Na(CH3OH)2]2[V(V)(DTBC)3]2.4CH3OH (where DBSQ = 3,5-di-tert-butylsemiquinone anion and DTBC = 3,5-di-tert-butylcatecholate dianion), and (iii) simple VO(acac)2. Product selectivity studies, catalytic lifetime tests, electron paramagnetic resonance spectroscopy (EPR), negative ion mode electrospray ionization-mass spectrometry (negative ion ESI-MS), and kinetic studies provided compelling evidence for a common catalyst or catalyst resting state, namely, Pierpont's structurally characterized vanadyl semiquinone catecholate dimer complex, [VO(DBSQ)(DTBC)]2, formed from V-leaching from the precatalysts. The results provide a considerable simplification and unification of a previously disparate literature of V-based catechol dioxygenases.

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“…Although a semiquinone ligand was clearly evident, shifting electronic charge from V III to one or two semiquinone ligands would give catecholate ligands and the metal in a higher oxidation state. Similarly, the reaction of 3,5-di-tert-butylcatechol with the heteropolyvanadate [PV V 14 O 42 ] 9in anaerobic acetonitrile gave a product formulated as the V III dimer [V III (DBSQ)-(DBcatH) 2 ] 2 ; however, proof of structure was not given for this complex either (Tatsuno et al, 1987).…”

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confidence: 99%

Reactions between Tunichrome Mm-1, a Tunicate Blood Pigment, and Vanadium Ions in Acidic and Neutral Media

1996

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Tunichromes are yellow, polyphenolic tripeptides prevalent in blood cells of tunicates (suborders phlebobranchia and stolidobranchia). Spectrophotometric studies of reactions between tunichrome Mm-1 and VV or VIV ions were conducted in vitro in various media to crudely approximate cellular conditions: deionized water, aqueous methanol, and aqueous buffers at pH 2 and 7. Catechol was used in parallel studies for comparison to tunichrome and was found to be a good model for tunichrome reactivity. For VIV in pH 7 buffer, both catechol and Mm-1 formed complexes with VIV ions, and no redox products were found. For VV in pH 2 buffer, both catechol and Mm-1 were oxidized by VV ions. Room temperature EPR qualitatively showed that Mm-1 in pH 2 buffer reduced VV ions to free VIV ions. For VV in pH 7 buffer, Mm-1 was oxidized by VV ions and formed VIV complexes. At higher concentrations, the VIV complexes were observed by low temperature EPR [Grant, K. B. (1994) Dissertation, Columbia University; Grant, K. B., et al. (1996) J. Inorg. Biochem. (manuscript in preparation)]. Using a colorimetric assay for VIII, we found that reactions between Mm-1 and VV or VIV ions in pH 7 buffer clearly did not generate appreciable quantities of VIII products. Thus, the colorimetric VIII assay resolved the issue of VIII product formation raised in EPR studies of Mm-1 [cf. Ryan, D. E., et al. (1992) Biochemistry 35, 8651-8661]. Overall, the results provide insights into tunichrome-vanadium chemistry and identify conditions which promote complexation and/or redox reactions in vitro.

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Heteropolyvanadates as catalysts for oxygenation of 3,5-Di-t-butylcatechol

Cited by 23 publications

References 17 publications

An All-Inorganic, Polyoxometalate-Based Catechol Dioxygenase That Exhibits >100 000 Catalytic Turnovers

An All-Inorganic, Polyoxometalate-Based Catechol Dioxygenase That Exhibits >100 000 Catalytic Turnovers

Vanadium-Based, Extended Catalytic Lifetime Catechol Dioxygenases: Evidence for a Common Catalyst

Reactions between Tunichrome Mm-1, a Tunicate Blood Pigment, and Vanadium Ions in Acidic and Neutral Media

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