Electrolytic reduction, apparatus

Electrolytic reduction, apparatus, 52, 23 Enol acetates, acylation of, 52,1 Enol esters, preparation, 52, 39 Epichlorohydrin, with boron trifluoride diethyl therate and dimethyl ether to give trimethyloxonium tetra-fluoroborate, 51,142 ESTERIFICATION OF HINDERED ALCOHOLS f-BUTYL p-TOLUATE,... 

See Amphetamine Syntheses Industrial for a detailed description of the electrolytic reduction apparatus. 

Method B 180 g tropine or pseudotropine is dissolved with 70 g ammonium sulphate in 720 g water, on which sulfuric acid up to the neutralization is added. This solution is made alkaline with ammonia poured into the anode region of the electrolytic reduction apparatus, while in the cathode area a solution of 280 g ammonium sulfate in 800 g water. The further procedure is then exactly the same, as described 1 in the example. Source Merck 1901... 

Schmieder(5) said that in the presence of hydrazine in a common cathode-anode space, there happens only the formation of U(IV) on the cathode without any reoxidation of it on the anode until the course of electrolysis reaches the stage of oxygen evolution on the anode. He said that this is due to the fact that oxidation of U(IV) has a high oyerpotential on the anode. Then it should be possible to construct an electrolytic reduction apparatus without a diaphragm. 

Sne electrolytic reduction apparatus as described in Airiphetamine Syntheses. 

The process is one of electrolytic reduction and the apparatus is similar to that shown in Fig. 77, p. 144. It consists of a small porous cell (8 cm. x 2 cm. diam.) surrounded by a narrow beaher (ii cm. X 6 cm. diam.). The oxalic acid, mixed w lth too c.f. 10 per cent sulphuric acid (titrated against standard baryl.a solution] forms the cathode liquid and is placed in Iht beakei. The porous cell is filled with the same strength of siilphuiic acid and foims the anode liquid. The electrodes ara made from 01 dinary clean sheet lead. The anode consists of i thiu strip projecting about two inches from the cell and tliu... 

Azoxybenzene from Nitrobenzene by Electrolysis.— Nitrobenzene can be conveniently converted into azoxybenzene by electrolytic reduction. The apparatus required is shown in Fig. 77. 

Electrolytic apparatus, 35, 22 Electrolytic reduction of e-chloronitroben-zene, 35, 23... 

The apparatus for electrolytic reductions (Fig. 5) may be an open vessel for work with non-volatile compounds, or a closed container fitted with a reflux condenser for work with compounds of high vapor pressure. Since the elec-... 

Electrolytic apparatus, 35, 22 Electrolytic reduction of o-chloronitro-benzene, 35, 23 Enanthaldehyde, 34, 51 Enanthaldehyde, 6-METHYL-/3-0X0-, dimethyl acetal, 32, 79... 

In addition to these procedures, electrolytic reduction of the nitro group has been accomplished, as illustrated by the preparation of o-amino-cyclohexylbenzene (85%) however, the procedure is rarely employed. An apparatus for large-scale runs has been described, and a comprehensive review of electrolytic reactions has been given. ... 

The first consideration is the choice of model system, and this may involve an aqueous electrolyte or nonaqueous media such as an organic electrolyte or molten salt. The selection of electrolyte and scavenger will depend on the energetics of the electrolyte reduction (good stability to reduction is needed) and upon the acceptor reactivity. Apparatus and electrochemical cells for metal/ electrolyte and semiconductor/electrolyte systems are similar generally. Some guidelines are presented below to assist with experimental practice (see also Chapter 3 in Ref. 10). Theses, also, are a good source of practical information, e.g., Refs. 20, 21, and 81. 

Chromium (II) chloride solutions can be prepared by any one of several different procedures. If pure electrolytic chromium is available, the procedure of Holah-Fackler (see synthesis 4) is recommended. Some modification as noted at the end of this procedure may be desirable. If metallic chromium is not available, commercial chromium(III) chloride may be reduced electrolytically (a suitable divided cell is needed), or the reduction may be effected by zinc and hydrochloric acid. The latter procedure, which starts with the most commonly available reagents and apparatus, is described here. 

It is a well-known fact that bubbles produced by mechanical force in electrolyte solutions are much smaller than those in pure water. This can be explained by reduction of the rate of bubble coalescence due to an electrostatic potential at the surface of aqueous electrolyte solutions. Thus, k a values in aerated stirred tanks obtained by the sulfite oxidation method are larger than those obtained by physical absorption into pure water, in the same apparatus, and at the same gas rate and stirrer speed [3]. Quantitative relationships between k a values and the ionic strength are available [4]. Recently published data on were obtained mostly by physical absorption or desorption with pure water. 

In general, in an electrolytic process, oxygen is evolved at the anode, and hydrogen at the cathode. If these electrodes are in different compartments, with a suitable electrolyte we may expect to have reactions of oxidation taking place in the anode compartment and reactions of reduction in the cathode compartment. In inorganic chemistry, the more successful electrolytic preparations are chiefly those of oxidation while in organic chemistry, reactions of both oxidation and reduction are often successful. In inorganic chemistry, reactions of reduction are usually effected in simple ways. The several units of the necessary apparatus are connected as shown in Fig. 10. 

The purification techniques have been refined so that the alumina is contained in a separate compartment of the apparatus and the impurities are removed by repeated cycling of the electrolyte through the alumina column and the cell (Lines et al., 1978). A diagram for the apparatus used to prepare stable solutions of radical anions by cathodic reduction in DMF is illustrated in Fig. 9. More recently further refinements have been made and water contents of acetonitrile solutions as low as 10- M have been estimated (Kiesele, 1981). 

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