Potassium hydroxide, hydrogenation with

In the absence of potassium hydroxide hydrogenation of vinylic and allylic chlorides to the saturated chlorides (with only partial or no hydrogenolysis of chlorine) is accomplished over 5% platinum, 5% palladium and, best of all, 5% rhodium on alumina [40]. 

Azoxybenzene has been prepared by reduction of nitrobenzene with alcoholic potassium hydroxide,1 with sodium amalgam,2 with hydrogen in the presence of lead oxide,3 with methyl alcohol and sodium hydroxide,4 with sodium methylate and methyl alcohol,5 and by electrolytic reduction 6 by oxidation of azobenzene with chromic anhydride 7 by treatment of /9-phenylhydroxylamine with alkaline potassium permanganate,8 with nitrobenzene,9 with mineral adds,10 and with mercury acetamide,11 and by oxidation of aniline with hydrogen peroxide,12 and with acid permanganate solution in the presence of formaldehyde.13 The procedure described above is a slight modification of one described in the literature.14... 

It seems to be necessary to convert the primary fuel into hydrogen or carbon monoxide first after this the cell functions well. The best-known application is in the combustion of hydrogen in aqueous potassium hydroxide electrolyte with nickel electrodes at 200°C, as used in the Apollo series space flights. 

Both anhydrous and hydrated sodium or potassium sulfide in ethanol have been used in the synthesis of thietanes. A common procedure is to use a solution of sodium or potassium hydroxide saturated with hydrogen sulfide. Liquid ammonia has been used as a solvent for the preparation of thietane (32%) from sodium sulfide and 1,3-dibromopropane. Phase-transfer catalysis has been used to good effect.A variation in which l,3-dichloro-3-methylbutane 3 is treated with aluminium chloride and hydrogen sulfide followed by aqueous sodium hydroxide gave 2,2-dimethylthietane 4 in 90% yield. An intermediate aluminium chloride-alkene complex, 5 or 6, was proposed. 

The reverse of this reaction also takes place for, when an alkyl halide, especially the iodide, is heated with alcoholic potassium hydroxide, or is passed over heated potassium hydroxide, hydrogen iodide is lost, and ethylene is obtained, as follows ... 

Tri-p-tolylstibine dihydroxide, (CHg.CgH4)oSb(OH)2/ is formed by treating a solution or suspension of tn-p-tolylstibme with 3 per cent, hydrogen peroxide in the presence of dilute potassium hydroxide, or with sodium peroxide. It is a crystalline product, M.pt. 225° C. 

In contrast to PEM electrolysis, which has only been utilized for around 25 years, alkaline electrolysis systems of various dimensions and types with outputs of up to 750 Nm h hydrogen have been available for some decades. For alkaline electrolysis, usually a potassium hydroxide solution with a concentration of 20-40 wt% is used. This is determined by the operating temperature, which is usually at 80 °C, since the ohmic losses can be minimized by a suitable concentration of the alkaline solution and thus optimal electrical conductivity [8]. The current density ranges from 0.2 to 0.4 A cm. The state of the art of large alkaline electrolyzers has not changed much over the last 40 years [9]. This becomes apparent in the fact that since the introduction of water electrolysis more than 100 years ago, only a few thousand systems have been produced and put into operation. Some of the systems listed in Table 11.3 are no longer produced, or their manufacturers have vanished from the market. 

The electronic structure of pyrrole allows us to understand not only the very weak basic properties of pyrrole but also its acidic character (p. 17). Pyrrole reacts with fused potassium hydroxide, or with potassium, to give potassium pyrrole, G4H4NK. The reaction with potassium proceeds smoothly, with evolution of hydrogen, in ligroin solution. Sodium pyrrole has not been obtained under such conditions, but pyrrole reacts with sodamide in liquid ammonia to give a compound C4H4lWa,NH3. This loses ammonia at 20°. Calcium and silver pyrrole can be prepared in the same way . 

Place 50 g. (57 ml.) of dry A.R. benzene and 0 5 ml. of dry p rridine (1) (dried over potassium hydroxide pellets) in a 500 ml. round-bottomed flask. Attach a reflux condenser to the flask and an inverted funnel (just dipping into some water in a beaker) to the top of the condenser (Fig. II, 13, 8, b). Partially immerse the flask in a bath of cold water, supported upon a tripod and gauze. Carefully pour 125 g, (40 ml.) of bromine (for precautions to be taken with bromine, see Section 111,35, Note 1) through a condenser and immediately insert the absorption device into the upper end of the condenser. A vigorous reaction soon occurs and hydrogen bromide is evolved which is absorbed by the water in the beaker when the reaction slackens, warm the bath to 25-30° for... 

Phenylpropiolic acid. This is an example of an aromatic acetylenic acid, and is made by adding bromine to the ethylenio linkage in ethyl cinnamate, and treating the resulting dibromide with alcohobc potassium hydroxide which eliminates two molecules of hydrogen bromide ... 

Oxidation of diphenylcarbazide (Section VII,3) with hydrogen peroxide in the presence of alcohoUo potassium hydroxide affords diphenylcarbazone ... 

---