Methanesulfonic acid, electrolyte

Figure 1.20 SEM image of Zn deposit on Sn layer deposited from a methanesulfonic acid electrolyte. Reproduced from reference [11].

Ferret, P, Z. Khani, T. Brousse, D. Belanger, and D. Guay. 2011. Carbon/PbOj asymmetric electrochemical capacitor based on methanesulfonic acid electrolyte. Electrochimica Acta 56 8122-8128. 

A novel kind of flow lead-acid battery with no separator and single electrolyte, lead(II) in methanesulfonic acid has been proposed recently [373]. 

The selective reduction of cyclic imidates (63) to the aldehyde oxidation level has been demonstrated by Shono et al. As shown in Scheme 19, the imidate is first alkylated on nitrogen and then reduced electrolytically in DMF in the presence of methanesulfonic acid. Unfortunately the scope of the method is unclear, as the main purpose of the work was to generate intermediate (64) in the presence of alkylating agents, leading to 2,2-disubstituted imidazolidines. Nonetheless, it was reported that decanal and dodecanal could be obtained in 82% and 70% yields, respectively. 

Figure 1.10. Schematic representation of EG40 electrolytic production of methanesulfonic acid (MSA) eluent (courtesy of Dionex Corp).

An analogous system can be used to generate methanesulfonic acid (MSA) eluent for the separation of cations (Fig. 1.10). In this case, the anode generates for eluent production. The cathode generates OH anion that combines with the H in the MSA electrolyte reservoir. MSA anion migrates across the anion exchange membrane to combine with the eluent cation (maintaining electric neutrality). 

An alternative electrolyte composed of methanesulfonic acid (CH3SO3H) and lead methanesulfonate has been proposed to address this problem [96], In this case, the redox reaction at the Pb02 electrode becomes solid/solvated ions in methanesulfonic acid-based electrolyte instead of a solid/solid couple in H2SO4 electrolyte [96] ... 

Dionex offers a just add water system for electrolyte generation and purification of commonly used eluents such as KOH and methanesulfonic acid. Eluents are generated from deionized water using an Eluent Generator (EG) cartridge and then polished of contaminants using a continuous-regeneration trap column. 

In the zinc/cerium system, methanesulfonic acid has been widely used as a supporting electrolyte. It is less corrosive than sulphuric acid, and its sufficient acid strength can dissolve a high concentration of cerium ions. Moreover, researchers suggested that the zinc dendritic growth can be inhibited by the methanesulfonic acid [50]. 

SC-CSRS 300 is a postcolumn electrolytic eluent suppressor package consisting of an eluent suppressor component (ES) and an analyte converter (AC) component that enables the suppressed conductivity detection of low-level ammonium and other amines. Figure 4.48 illustrates the ion movement through a SC-CSRS 300 in detail. The eluent and the ammonium analyte (an example of the cation analytes) exit the analytical column as methanesulfonic acid (H" MSA ) and ammonium methanesulfonate (NH4 MSA ). In the eluent suppressor component, the majority of the eluent is suppressed to water and the analyte is converted to the base form, NH4" OH . However, a small amount of MSA reenters the eluent chamber near the exit, which converts the analyte back to the salt form, so that the analyte exits the eluent suppressor component... 

In 2001, a third type of suppressor -Atlas Electrolytic Suppressor (AES) - was introduced. The Atlas suppressor is a continuously regenerated suppressor operated in the recycle mode and designed for optimal performance with conventional methanesulfonic acid (MSA) eluents. Able to suppress up to 25mmol/L... 

When comparing the level of development of ion chromatography in the year of publication of the third edition of this book with the development stage more than 10 years later, one cannot help seeing another quantum step in the development of this method. Pioneering developments such as the contamination-free electrolytic preparation of hydroxide and methanesulfonic acid eluents with the related simplification of gradient techniques, the new trend toward 4 pm... 

The a values obtained in this manner have an uncertainty of 0.08 and are listed in Table 3.9 adopted from [3]. Water has a large value of a = 1.17, but certain phenols and halogen-substituted alkanols and carboxylic acids are considerably more acidic hexafluoro-i-propanol has a = 1.96, dichloroacetic add has a = 2.24, and trifluoro-methanesulfonic acid has AN = 131.7, much higher than the value for water, 54.8, but these are rarely used as solvents for electrolytes and therefore are not dealt with further here. 

Methanesulfonic acid is preferentially used as the electrolyte on both sides to increase the solubility of the metal cations [111]. Zinc-cerium chemistries enable a very high cell voltage. However, the concomitant parasitic reactions such as HER and OER must be avoided or minimized to achieve acceptable cell efliciencies. 

Investigation of electrochemical characteristics of Cr(III) methanesulfonate complexes draws a special attention in view of ecological and technical benefits concerning production of metal electrodeposits [32, 33], The electrochemical systems comprising methanesulfonic acid (MSA) and its salts are known to have many advantages [34]. However, kinetics of Cr(III) electroreduction in MSA containing electrolytes has yet been studied insufficiently. 

The Cr(III) electroreduction process on the lead, cadmium and tin electrodes has been shown to be irreversible in electrolytes containing methanesulfonic acid [17, 35] the corresponding voltammograms obey satisfactorily Equations (23) and (34). The electroreduction of Cr(III)-MSA complexes proved to proceed via an outer-sphere mechanism. Some kinetic parameters of one-electron Cr(III) electroreduction in methanesulfonate and sulfate electrolytes (i.e. standard rate constant and transfer coefficient) were determined at the standard temperature (298 K) in works [17, 35]. 

In dry acetonitiile/sodium perchlorate, however, sodium methanesulfonate and CO is obtained. A methylthiomethyl cation 159, (Eq. (220) ), is believed to be an intermediate, which is hydrolyzed to formaldehyde and methyl mercaptane. Both products are subsequently oxidized by C1207, formed by dehydration of perchloric acid, to CO and NaS03CH3 465 In spite of the fact that epe was conducted well below the discharge potential of the supporting electrolyte complications arose (Eq. (220) ), that were attributed to anodically generated C104 This observation asks for caution in the use of perchlorates as supporting electrolytes in apro-tic solvents. If possible, tetrafluoroborates or hexafluorophosphates should be used instead. 

Martyak, N.M. and Seefeldt, R. (2004) Additive-effects during plating in acid tin methanesulfonate electrolytes. Electrochim. Acta, 49 (25), 4303 -4311. 

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