On the first equilibrium steps in the acidification of the molybdate ion

Sasaki, Yoh; Lindqvist, Ingvar; Sillén, Lars Gunnar

doi:10.1016/0022-1902(59)80016-6

Cited by 82 publications

(16 citation statements)

References 9 publications

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“…The chemistry of molybdenum(VI) in aqueous solutions has been an area of intense activity since the late 1950s (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Because of the existence of anionic, cationic, and polymeric species, the behavior of molybdenum in the extraction experiments is complicated to understand.…”

Section: Introductionmentioning

confidence: 99%

EXTRACTION OF MOLYBDENUM FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYL-PHOSPHINE OXIDE

Fujii

Yamana

Watanabe³

et al. 2001

Solvent Extraction and Ion Exchange

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The extraction behavior of molybdenum(VI) under the conditions of transuranium extraction (TRUEX) process was studied by using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide. The extraction behavior of molybdenum(VI) under the condition of PUREX process was also investigated for comparison. The extraction of molybdenum with the copresence of uranium(VI), dysprosium(III), and the effect of oxalic acid were examined. Under the PUREX conditions, molybdenum was less extractable, while under the TRUEX process conditions, a higher distribution ratio of molybdenum was observed. Under the TRUEX conditions, the addition of oxalic acid was effective in depressing molybdenum extraction. It was concluded that, at the concentration of nitric acid ORDER REPRINTS 128FUJII ET AL.around 1 mol dm −3 or higher, Mo(VI) is extracted predominantly as cationic species, while at lower concentration of nitric acid, the coextraction of anionic molybdenum as a mixed complex with other metal, that is, UO 2+ 2 , occurs.

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Section: Introductionmentioning

confidence: 99%

EXTRACTION OF MOLYBDENUM FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYL-PHOSPHINE OXIDE

Fujii

Yamana

Watanabe³

et al. 2001

Solvent Extraction and Ion Exchange

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“…17 The nucleophilicity of molybdate is remarkable, given its low basicity (pK a 4.1). 19 To determine if molybdate could also act as a catalyst of imido-group hydrolysis, we incubated succinimide 2 with varying concentrations of Na 2 MoO 4 in 0.50 M HEPES-NaOH buffer at pH 7.5, containing NaCl (0.10 M). 20 The resulting kinetic traces were indicative of substantial catalysis ( Figure 1A).…”

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confidence: 99%

Catalysis of imido group hydrolysis in a maleimide conjugate

Kalia

Raines

2007

Bioorganic & Medicinal Chemistry Letters

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Maleimides are often used for biomolecular conjugation with thiols. An underappreciated aspect of the imido group in a maleimide conjugate is its susceptibility to spontaneous hydrolysis, resulting in undesirable heterogeneity. Here, a chromophoric maleimide is used to demonstrate that both molybdate and chromate catalyze the hydrolysis of an imido group near neutral pH. Tungstate and 4-(dimethylamino)pyridine are less effective as catalysts. This work reveals a new mode of chemical reactivity for molybdate and chromate, and provides a strategy for decreasing the heterogeneity of bioconjugates derived from maleimides.Chemoselective bioconjugation has revolutionized functional genomics, proteomics, and glycomics 1 . Reactions, such as the Staudinger ligation, 2 the Huisgen 1,3-dipolar cycloaddition, 3 carbonyl group condensation reactions, 4 and maleimide conjugation 5 enable the site-specific labeling of biomolecules, and their uniform immobilization to generate microarrays.Bioconjugation via maleimides is especially common. This reaction involves the Michael addition of a biomolecular thiolate, often from the side chain of a cysteine residue, to a maleimide to form a succinimidyl thioether. 6, 7 The reaction proceeds rapidly and in high yield in neutral aqueous solutions at room temperature, making it ideal for biological applications.An underappreciated aspect of maleimides and succinimides is the tendency of their imido groups to undergo spontaneous hydrolysis. 8, 9 As water can attack either of the two carbons of the imido group, hydrolysis of a succinimidyl thioether produces isomeric succinamic acid thioethers. Accordingly, a thiol-conjugated maleimide actually consists of a mixture of many species, some having an additional carboxylic acid that can ionize near neutral pH. As hydrolysis proceeds over time, the concentrations of these species change, introducing yet another complexity.The heterogeneity of succinimidyl thioethers can alter the activity of bioconjugates and convolute the interpretation of experimental data. For example, an N-(1-pyrene)maleimideconjugate of α,α-tropomyosin was observed to hydrolyze in aqueous solution, causing a timedependent increase in fluorescence. 10 The cellular internalization of some peptides and proteins relies on their cationic charge, 11 and the presence of a hydrolyzed succinimidyl thioether could complicate data analysis by reducing that charge. Surface-based assays can be especially sensitive to heterogeneity within the immobilized species. For example, the *Corresponding author at present address: Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706-1544; e-mail: raines@biochem.wisc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable for...

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“…In the solutions with pH lower than 7, there is evidence from pH data for the following equilibria eq. 1-4 [4]: …”

Section: Molybdates (Vi)mentioning

confidence: 99%

“…(NH 4 The precatalyst was filtered and washed with distilled water to remove all ionic co-products. The precatalyst was insoluble and unreactive in water.…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…After half an hour reaction time, at a pressure of 12 bar, and at a temperature of 573ok , less than 8% of carbon dioxide converted into products (CO %7 and CH 4 <1). At the same condition when temperature was raised up to 973 o k; about 49% of carbon dioxide was converted into products (CO 44.2% and CH 4 4.6%). The reaction compositions including CO 2 , CO, H 2 and CH 4 with temperature were demonstrated in Figure 6.…”

Section: Nova Journal Of Engineering and Applied Sciences Page: 4 Co mentioning

confidence: 99%

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Hydrogenation of Carbon Monoxide and Carbon Dioxide over Nano γ-Alumina Supported Cobalt (III)/Molybdenum Catalyst

Takassi

Helalizadeh

Rad

2016

Nova J Eng Appl Sci

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Ligated dicobalt (III) heptamolybdate (CoL 6 ) 2 (Mo 7 O 24 ) multitransition-metal complex was prepared. This complex was deposited evenly on nano γ-alumina catalyst support. The partial reduction of cobalt (III)/ molybdate pre-catalyst was performed in a batch reactor with hydrogen gas at a pressure of 20 bars and temperature of 873 o K for 5 hours. The catalyst was characterized using FTIR, XRD, BET and TEM. The nano cobalt (III)/molybdenum catalyst was employed for hydrogenation reaction of carbon monoxide and carbon dioxide. The assessment of the catalyst was carried out at different temperature over a pressure range of 10-50 bars with various H 2 /CO ratios. This catalyst was found to be active, and stable for usage at high temperature and moderate pressure. The catalyst gave an excellent conversion of carbon monoxide to hydrocarbons (95%); it also converted 78% of carbon dioxide to carbon monoxide (73) and methane (5%). TEM image demonstrated catalyst has nearly spherical morphology with the average particle size of 46.86 nm.

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On the first equilibrium steps in the acidification of the molybdate ion

Cited by 82 publications

References 9 publications

EXTRACTION OF MOLYBDENUM FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYL-PHOSPHINE OXIDE

EXTRACTION OF MOLYBDENUM FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYL-PHOSPHINE OXIDE

Catalysis of imido group hydrolysis in a maleimide conjugate

Hydrogenation of Carbon Monoxide and Carbon Dioxide over Nano γ-Alumina Supported Cobalt (III)/Molybdenum Catalyst

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