Chloranil electrode

USE Fungicide. In manuf of chloranil electrodes for pH measurements. As reagent for pamaquine (Plasmochin) in urine (blue color) Schulemann et ai, Chem. Zentr. 1928, I, 2193. Two of the chlorine atoms in para position are easily subetituted, and compds such as 2,5-dianitino-3,6-dichloro-quinone are much used in the dye industry. Caution May ba irritating to skin, mucous membranes. 

For electromotive force measurements there are many suitable electrodes, and only the most novel features can be summarised here. The glass electrode is generally usable in these solvents. It has been found that in solutions of hydrochloric acid in anhydrous acetic acid, the glass electrode is subject to acid errors of as much as 70 mV relative to the chloranil electrode, owing to the incorporation of chloride ions in the surface gel layer of the glass. ° Since ethylenediamine reacts with calomel but not with mercury (II) chloride, a suitable reference electrode for this solvent can be constructed of a mercury pool in contact with ethylenediamine saturated with respect to both HgClg and LiCl. °... 

The relative pK values of the ring nitrogen atoms may be estimated from the HCl numbers. Or they may be determined directly by titrating the weak bases potentiometrically in glacial acetic acid with perchloric acid using the chloranil electrode (18). In a comprehensive analysis of this... 

Mercury(II) chloranilate 700 Mercury(II) nitrate standard soln. of, 359 Mercury/mercury( II )-EDTA electrode (mercury electrode) 586 potentiometric titration of metallic ions with EDTA and, 588 prepn. of, 587 Mercury thiocyanate 700 Metaphosphoric acid in homogeneous precipitation, 426 Metal apparatus 93 Metal ion buffer 53... 

The oxidation of N ADH has been mediated with chemically modified electrodes whose surface contains synthetic electron transfer mediators. The reduced form of the mediator is detected as it is recycled electrochemically. Systems based on quinones 173-175) dopamine chloranil 3-P-napthoyl-Nile Blue phenazine metho-sulphatemeldola blue and similar phenoxazineshave been described. Conducting salt electrodes consisting of the radical salt of 7,7,8,8-trtra-cyanoquinodimethane and the N-methylphenazium ion have been reported to show catalytic effects The main drawback to this approach is the limited stability... 

In fact, it is based on an equimolar mixture of tetrachloroquinone (chloranil) and tetra-chlorohydroquinone (hydrochloranil) at a white Pt electrode. 

In the paper from V. Matveyev of the Ukrainian State University of Chemical Engineering, an examination of the role of conductive carbon additives in a composite porous electrode is conducted. A model for calculation of the local electrochemical characteristics of an electrode is presented. A comparison on the polarization of the electrode as a function of the redox state of the electroactive species is emphasized in the model. The electrochemical reaction of chloranil (tetrachlorobenzoquinone) was measured and results compare favorably to calculations derived from the model. 

Theoretical model porous electrode solid reagent dissolution electrochemical reaction crystallization polarization characteristic chloranile carbon black. 

Lobacz et al. [52] have described partial adsorption ofTl+-cryptand (2,2,2) complex on mercury electrode. From voltocoulom-etry, cyclic voltammetry, and chrono-coulometry, it has been deduced that electroreduction of this complex proceeds via two parallel pathways from the solution and from the adsorbed states, which are energetically close. Also, Damaskin and coworkers [53] have studied adsorption of the complexes of alkali metal cations with cryptand (2,2,2) using differential capacity measurements and a stationary drop electrode. It has been found that these complexes exhibit strong adsorption properties. Novotny etal. [54] have studied interfacial activity and adsorptive accumulation of U02 " "-cupferron and UO2 - chloranilic acid complexes on mercury electrodes at various potentials in 0.1 M acetate buffer of pH 4.6 and 0.1 M NaCl04, respectively. 

The behavior of 4,4 -dimethoxystilbene on the electrode and with p-chloranil in solutions was compared (Todres Ionina 1992). It was found that the cis and trans isomers of the compound form different charge-transfer complexes with chloranil that are unlike in color and can be converted conversion was found to be in the cis-to-trans direction. Reverse conversion is not observed, and cyclization is also not detected (which takes place in the case of 4-methylstilbene) (Scheme 2-6). 

Si/BDD electrodes are able to achieve faster oxidation and better incineration efficiency than Ti/Pb02 in the treatment of naphthol (Panizza and Cerisola 2004b) (Fig. 2.12), 4-chlorophenol (Gherardini et al. 2001), and chloranilic acid (Martinez-Huitle et al. 2004b). 

Martinez-Huitle, C. A., Quiroz, M. A., Comninellis, C., Ferro, S. and De Battisti, A. (2004b) Electrochemical incineration of chloranilic acid using Ti/Ir02, Pb/Pb02 and Si/BDD electrodes. Electrochim. Acta 50, 949-956. 

Data based on tables in Ref. [2] and references therein values in eV obtained in acetonitrile, H20, or other polar solvents redox potentials are reported vs. standard calomel electrode calculation of AGeI performed with Eq. (13). Abbreviations CA = chloranil CN = 1-cyanonaphthalene bpy = 2,2 -bipyridine, MV2+ = methylviologen dicp = 1,3-diisocya-nopropane and TMB = N,N,iV, N -tetramethylbenzidine... 

The quinhydrone electrode has been adapted for pH measurements in non-aqueous media, such as alcohols, acetone, formic acid, benzene and liquid ammonia. For the determination of hydrogen ion activities in solutions in pure acetic acid a form of quinhydrone electrode involving tetrachloroquinone (chloranil) and its hydroquinone has been used. ... 

Starting with a quinone electrode (No. 1), the copper salt/diaphragm/hydro-quinone r.b. is claimed in a patent [543]. The cyclability is excellent, but the voltage is less than 0.5 V. One advantage is the impossibility of generation of H2, a gas which cannot easily be recycled in an r.b. An alternative to the quinone accumulator (cf. Sections 2 and 9.3) is the Zn/chloranil cell [71-74]. 

The tetrachloroquinone (chloranil)/tetrachlorohydroquinone system has been used as a reference electrode in alcohols and acetic acid [222], often in the presence of an excess mineral acid. The half-cell consisted of a platinum electrode in a solution saturated with respect to both chloranil and the hydroquinone. The electrode is well poised, and at constant temperature and constant hydrogen ion activity the potential is stable. 

Reduction of 1,3-thiazinium salts in acetonitrile yield 6,6 -bi-l,3-thiazinyls the 6,6 -bi-l,3-thiazinyls are oxidized to thiazinium salts at a platinum electrode, whereas dehydrogenation by chloranil affords 6,6 -bi-l,3-thiazinylidene [293]. 

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