Electrolytes, supporting lithium chloride

The carbon-nitrile bond in cyanoalkanes is cleaved by reduction at very negative potentials. This is the route for decomposition of acetonitrile at tlie limit for its use as an aprotic solvent in electrochemistry [114, 115]. Preparative scale reduction of cyanoalkanes is best carried out in anhydrous ethylamine containing lithium chloride as supporting electrolyte and gives 60-80 % yields of the alkane plus cyanide ion. 

The above explanation of acclimatisation is supported by the results obtained on adding mixtures of electrolytes to the hydrosol. Hydrolysis of the coagulating electrolyte has a pronounced influence and the presence of one electrolyte may diminish the coagulating power of another. More magnesium chloride is required to coagulate a sol containing lithium chloride than is required in the absence of lithium chloride. Also in the presence of sodium benzoate or sodium nitrite, more than the calculated quantity of potassium or barium chloride is required for precipitation. 

Electrolytic preparation of sym-triazines has been reported electrolysis at a mercury cathode of N,AT-dimethylcyanamide (45) containing lithium chloride as supporting electrolyte produced... 

Amides may be reduced to aldehydes electrochemically in methylamine, with lithium chloride as the supporting electrolyte.Despite the apparent similarity between this and the foregoing method, the results are rather different. With no added proton donor, overreduction occurs leading to the corresponding alcohol. It is only in the presence of ethanol that aldehydes are obtained in reasonable yields. Another difference is that secondary amides give satisfactory yields, as shown in Table 8 where this and the foregoing method can be compared. 

A number of 1,1-dihalocyclopropanes have been reduced electrochemically to monohalides using a mercury cathode in an appropriate solvent containing a supporting electrolyte, e.g. reduction of 38 (Table 4)112,130 ggg j.gj-g 128-130, 132, 133, 745, 758), but few reactions have been carried out on a preparative scale. One exception is 9,9-dibromobicyclo[6.1.0]nonane which is converted stereospecifically to exo-9-bromobicyclo[6.1.0]nonane (39) in better than 80% yield at a mercury cathode at 0°C using methanol as solvent and lithium chloride as supporting electrolyte. A reaction resulting in 17% asymmetric yield is described in ref 886. 

The supporting electrolytes (when used) were 0.01-mol/L lithium chloride in aqueous phase and 0.01-mol/L tetrabutylammonium tetraphenylborate (TBATPB) in nitrobenzene. 

TPAs+), and crystal violet (CV+) with tetraphenylborate as the counterion. Lithium chloride is the aqueous phase supporting electrolyte. 

Addition methods were used for the determination of m-saturated compounds and olefins. The methods are based on the additions of bromine to unsaturated bonds, and the waves for the brominated compounds corresponding to the reduction of o, j8-dibromides (involving elimination) are measured. Their heights are proportional to the concentration of the unsaturated compound. Thus vinylchloride and 1,2-dichloroethylene were transformed into l-chloro-l,2-dibromoethane and l,2-dichloro-l,2-dibromoethane, by the action of a 3 M solution of bromine in methanol saturated with sodium bromide. The excess of bromine was removed with ammonia and the polarographic analysis was performed with sodium sulphite or lithium chloride as a supporting electrolyte. On the other hand, acetylene, vinyl-chloride, 1,2-dichloroethylene and 1,1,2-trichloroethylene were determined ) after a 24 hr reaction with bromine in glacial acetic acid (1 1). The excess bromine was removed with a stream of nitrogen or carbon dioxide. An aliquot portion is diluted (1 10) with a 3 M solution of sodium acetate in 80 per cent acetic acid and after deaeration the curve is recorded. 

Oxygen derivatives. A methanol-benzene (1 1) mixture containing 0-3 M lithium chloride as supporting electrolyte, was first... 

A supporting electrolyte that produces negligible alkaline error, such as salts of magnesium, calcium, barium, or organic cations, should be used. Lithium chloride or sodium perchlorate are recommended for alcoholic media. Some common solvents in which tetrabutylammonium iodide (BU4NI) and tetraethylammonium perchlorate (Et4NC104) are soluble are listed in Chapter 3. 

Fig. 12. Dependence of heights of first (1), second (2), and total (3) wave of maleic acid in dimethylformamide with 0.1 N lithium chloride solution as supporting electrolyte on concentration of lithium hydroxide added.

Fig. 13. Semilogarithmic curves for wave in dimethylformamide solution of mono-lithium maleate (0.7 mmole/liter) with 0.1 N lithium chloride as supporting electrolyte. 1) Without additions 2)-4) with addition of 0.3 mmole/liter and 0.7 mmole/liter formic acid (2,3) and 1,0 mmole/liter phenylacetic acid (4).

Tetraalkylammonium tosylates [74] and trifluoromethanesulfonates [72] are also excellent electrolytes. Although tetraalkylammonium ions are favored as the cations for supporting electrolytes because of their wide potential range, other cations are sometimes used for special applications—for example, methyltri-phenyl phosphonium, whose tosylate is freely soluble in methylene chloride, and other fairly nonpolar solvents [74] or metal ions (lithium salts tend to have the best solubility in organic solvents) where undesirable reactions of the tetraalkylammonium ion might occur [13,75]. The properties of many electrolytes suitable for nonaqueous use have been surveyed [76]. 

If the reactions are carried out in a nitrile as solvent, rather than dichloromethane, using triflic acid as catalyst, a modified Ritter reaction takes place, and the intermediate nitrilium ion traps the liberated amine, forming an amidine (Scheme 67). In an earlier reaction cf. Scheme 67) the lithium perchlorate catalyzed reaction of sulfenyl chlorides with alkenes in the presence of nitriles had also given l-amido-2-sulfenyl adducts. Ritter products are also obtained in good yields by anodic oxidation (Pt or C, 1.2-1.4 V) of disulfides in acetonitrile, in the presence of excess alkene, using B114NBF4 as supporting electrolyte (Scheme 68). ... 

Carbon and graphite are often used as supports for electrocatalysts, but they also have an electrocatalytic function in electrode reactions such as oxygen reduction in alkaline electrolytes, chlorine alkali industry, and SOCI2 reduction in lithium-thionyl chloride batteries. 

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