Continuous Coulometric Titration of Unsymmetrical Dimethylhydrazine.

Buck, Richard P.; Eldridge, R. W.

doi:10.1021/ac60229a018

Cited by 16 publications

(6 citation statements)

References 10 publications

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“…When the receptor and substrate form a complex (16) the molecular recognition phenomenon dictates that there will be some size/shape selectivity in RH 2 's preference for various species. On the other hand, the proton transfer reaction (17) would seem to involve no such recognition.…”

Section: Resultsmentioning

confidence: 97%

“…17 It controls the potential difference between two reference electrodes by passing current through two auxiliary electrodes. It can compensate, by positive feedback, up to 10 kΩ of uncompensated resistance between the reference electrodes.…”

Section: Methodsmentioning

confidence: 99%

“…The circuit used for the four-electrode potentiostat is based on the work of Figaszewski, 16 which in turn derives from work of Buck. 17 It controls the potential difference between two reference electrodes by passing current through two auxiliary electrodes. It can compensate, by positive feedback, up to 10 kΩ of uncompensated resistance between the reference electrodes.…”

Section: Methodsmentioning

confidence: 99%

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Direct Observation of Chloride Transfer across the Water/Organic Interface and the Transfer of Long-Chain Dicarboxylates

and

Weber

1996

J. Phys. Chem.

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We have extended the negative side of the potential window by using the organic reference electrode Ag/ AgTPB and a low supporting electrolyte concentration in the aqueous phase. We have observed directly, for the first time, the voltammetric wave of chloride transferring across the water(W)/1,2-dichloroethane (1,2-DCE) and the water/nitrobenzene (NB) interfaces. The standard potentials (and the standard Gibbs free energies of transfer) have been evaluated by consideration of half-wave potentials, the variations of the activity coefficients in both phases, and ion-pair formation. Our best estimate for the free energy of Cl -transfer to water-saturated 1,2-DCE is 45-46 kJ/mol, and for NB 38 ( 2 kJ/mol. The Gibbs free energies of transfer of a homologous series of long-chain dicarboxylates have also been obtained for the first time. They show a similar dependence on carbon number as monocarboxylates. The transfers of the singly and doubly ionized dicarboxylic acids can also be observed simultaneously when the pH of the aqueous phase is controlled in the range of 5.5-6.6. Shorter chain dicarboxylates, such as glutarate, -OOC(CH 2 ) 3 COO -, cannot be transferred across either the W/1,2-DCE or W/NB interface because it is more thermodynamically uphill than the transfer of the aqueous electrolyte anion or the organic electrolyte cation. One way to overcome some of the thermodynamic barrier is to use a receptor in the organic phase that would result in facilitated transfer. Our data show that a receptor for glutarate that had a formation constant of about 10 3 for a receptor-glutarate complex would allow for facilitated transfer. Through use of literature data for the transfer of the neutral dicarboxylic acids and H + , we can estimate the difference in pK a values between the aqueous phase and the water-saturated nonaqueous phases. In 1,2-DCE we estimate the differences for first and second ionizations as 18.5 and 19.5, respectively, while for NB they are 13.8 and 14.4.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Direct Observation of Chloride Transfer across the Water/Organic Interface and the Transfer of Long-Chain Dicarboxylates

and

Weber

1996

J. Phys. Chem.

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“…To predict voltammetric curves at small interfaces, it is useful to assume that the transport area of a minute disk interface is equal to the surface of the hemisphere, which would enclose the disk. A solution for the limiting case of the interfacial radius r-~ 0 using this model yields for the maximum limiting current an expression I(approx) : 27rnF Dc*r [3] r~0 This relationship gives a larger value than the exact expression derived for a disk microelectrode by Aoki and Osteryoung (26) and by Shoup and Szabo (27) I~o = 4nFDc*r [4] The merit of using the approximation based on the spherical term from (25) is that it allows simulation of the entire voltammetric curve at an arbitrary potential, whereas (26) gives results only for the limiting steady-state current.…”

Section: U (Mv)mentioning

confidence: 93%

“…One problem that often hinders experimental work on ITIES is the low conductivity of the system, which results in high ohmic IR drop. Several techniques for the ohmic drop elimination, typically based on a special four-electrode potentiostat, were proposed (4)(5)(6)(7)(8). Another method * Electrochemical Society Active Member.…”

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confidence: 99%

Ion Transport across a Microscopic Interface between two Immiscible Electrolytes

Vanýsek

Hernandez

1990

J. Electrochem. Soc.

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Voltammetric characteristics of a small interface (microinterface) formed between two immiscible solutions of electrolytes was examined. Comparison was made with the results obtained with a larger size liquid/liquid interface on which the charge-transfer behavior has been studied. The response observed with the microinterface generally resembles that observed with solid microelectrodes in redox systems. The transport across the water-nitrobenzene interface has been investigated by addition of semihydrophobic ions such as tetramethylammonium, tetraethylammonium, picrate, choline, and dodecylsulfate. The microinterface reduces the effect of IR ohmic drop in the system and makes it possible to work with two electrode systems without a potentiostat.Voltammetric studies on interfaces between two immiscible electrolyte solutions (ITIES) have seen a steady increase in interest in the past years. Our contribution is oriented toward the possibilities and advantages of a scaled down interface (1). The interest in ITIES.is not entirely new; a few works date back at least a century (2). The modern experimental approach was undertaken after 1976 when Koryta et al. (3) had shown that an interface between

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Alkylpyridines and Miscellaneous Organic Nitrogen Compounds

Trochimowicz¹,

Kennedy²,

Krivanek³

2001

Patty's Toxicology

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This chapter covers additional aliphatic and aromatic compounds that contain one or more nitrogen atoms in their structures and follows those discussed in Chapter 59. Pyridine and its many modified structures are described because they serve as a backbone for many industrial compounds. Several pesticides and herbicides, as well as their precursors, are included: the pyridinethiones, the substituted uracils herbicides: bromacil, lenacil, terbacil; the quaternary herbicides: paraquat, diquat, and difenzoquat; the s ‐triazines: atrazine and propazine and other triazine herbicides, such as ametryn, prometryne, and simazine. Simple nitrogen compounds such as azides, nitrosamines, and hydrazines are described because of important toxicological effects they can produce. Finally, two important industrial solvents, dimethylacetamide and dimethylformamide are included because they have a long history of use and have been well studied in the occupational environment.

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Continuous Coulometric Titration of Unsymmetrical Dimethylhydrazine.

Cited by 16 publications

References 10 publications

Direct Observation of Chloride Transfer across the Water/Organic Interface and the Transfer of Long-Chain Dicarboxylates

Direct Observation of Chloride Transfer across the Water/Organic Interface and the Transfer of Long-Chain Dicarboxylates

Ion Transport across a Microscopic Interface between two Immiscible Electrolytes

Alkylpyridines and Miscellaneous Organic Nitrogen Compounds

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