Fractional electrolysis

CONCENTRA TION OF THE ISOTOPE OF HYDROGEN B Y THE FRACTIONAL ELECTROLYSIS OF WATER ... 

Shortly after the discovery of deuterium by H. C. Urey, Gilbert Newton Lewis prepared 1 ml of nearly pure deuterium oxide by the continued fractional electrolysis of ordinary water. Since then heavy water has been very carefully studied and new" methods have been developed for its isolation which permit it to be made in large quantities. Its density at 20 is 1.1059 g Vm ", its freezing point is 3.82°, its boiling point 101.42°, and its temperature of maximum density 11.6° C. 

Separation of isotopes of Li is another example of the application of fractional electrolysis for separating isotopes. Taylor and Urey (1933) carried out repeated electrolysis of a solution of LiOH using mercury as the cathode, when an amalgam rich in 6Li was obtained. 

Fractional electrolysis has also been applied to the study of hormones. Freeman, Gulland, and Randall (1935) reported that the oxytocic hormone of the posterior lobe of the pituitary gland remained in the center compartment of an electrodialysis cell at reactions more alkaline than pH 8, but moved toward the cathode at more acid reactions. They were unable to purify the hormone by electrodialyas since the removal of a proteoselike material seemed to reduce the stability of the hormone toward alkali. Das, Ghosh, and Guha (1936) used a three-chambered apparatus with two additional chambers carrying reversible electrodes for the determination of the isoelectric point of the hormone they con-... 

Deuterium.— A heavy isotope of hydrogen, H, was discovered in 1932, by H. M. Urey and his colleagues, and subsequently termed deuterium, D. Deuterium oxide, DgO, occurs in all natural waters, the proxmrtion being about 1 6,000 in rain water. This heavy tmter fraction can be concentrated by evaporation, and by fractional electrolysis the HgO can be removed. 

Although isotopes have similar chemical properties, their slight difference in mass causes slight differences in physical properties. Use of this is made in isotopic separation pro cesses using techniques such as fractional distillation, exchange reactions, diffusion, electrolysis and electromagnetic methods. 

Myristic acid from hexanoic acid and methyl hydrogen sebacate). Dissolve 23 -2 g. of redistilled hexanoic acid (re caproic acid), b.p. 204-6-205-5°/760 mm., and 21-6 g. of methyl hydrogen sebacate in 200 ml. of absolute methanol to which 0 13 g. of sodium has been added. Electrolyse at 2 0 amps., whilst maintaining the temperature between 30° and 40°, until the pH is about 8 0 (ca. 6 hours). Neutralise the contents of the electrolysis cell with a little acetic acid and distil off the methyl alcohol on a water bath. Dissolve the residue in 200 ml. of ether, wash with three 50 ml. portions of saturated sodium bicarbonate solution, once with water, dry with anhydrous magnesium sulphate, and distil with the aid of a fractionating column (see under Methyl hydrogen adipate). Collect the re-decane at 60°/10 mm. (3 0 g.), the methyl myristate at 158-160°/ 10 mm. (12 5g.) and dimethyl hexadecane-1 16-dicarboxylate at 215-230°/ 7 mm. (1 -5 g.)... 

Industrially, it is manufactured either by fractional distillation of air, or by electrolysis of sodium hydroxide and it is distributed as a non-liquefied gas in pressurized black cylinders at ca 2200 psig at 21°C. Since it is non-corrosive no special materials of construction are required. 

Pyridine has been phenylated with the following free-radical sources benzenediazonium chloride with aluminum trichloride the Gomberg reaction " phenylhydrazine and metal oxides A -nitroso-acetanilide dibenzoyl peroxide phenylazotriphenylmethane di-phenyliodonium hydroxide and electrolysis of benzoic acid. ° Although 2-phenylpyridine usually accounts for over 50% of the total phenylated product, each of the three phenyl derivatives can be obtained from the reaction by fractional recrystallization of the... 

During the deposition step, some fraction of the total analyte is deposited into the mercury electrode by electrolysis for a given length of time. An exhaustive electrolysis, in which all of the analyte is deposited into the electrode, is time consuming and generally unnecessary, since adequate concentrations can usually be deposited into... 

The volume of the metal produced depends on the current density, the electrolysis time, the cathode area, and the electrochemical equivalent. Yt is usually expressed as a function of the current density. The interrelationship among Yt, the specific area of the cathode, As (m2/m3), i.e., the area of the cathode per unitvolume of the reactor (cathode area/volume of the cell), the fractional current efficiency, T, and the current density, I, is given by ... 

Two other concepts are of importance in electrolysis, viz., the current density, i.e., the current per unit surface area, j = i/A, and the current efficiency, i.e., the amount of ion converted as a fraction of that which, according to... 

Fig. 35. Mole fractions of intermediates and product during electrolysis of PCP (290)...

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