Potassium ethyl-carbonate

Habermann, on electrolyzing the alcohol in alkaline solution, obtained, besides carbon dioxide, an aldehyde resin (Ludersdorf and Connel 6) from which he isolated a body closely related to cinnamic aldehyde. In aqueous solution, on the addition of potassium acetate, the alcohol was split up into ethane, potassium ethyl-carbonate, carbon dioxide, and acetic ester. 

A glass reactor placed in a steel autoclave was charged with phenol (2.35 g, 0.025 mol) and potassium ethyl carbonate (3.46 g, 0.027 mol). The autoclave was closed, and carbon dioxide was fed to a pressure of 25 atm in two steps. The reaction mixture was stirred at this pressure, and its temperature was raised for 6 h to 215 °C (heating rate 32 °C/h) and then kept at this temperature for 1 h. After cooling to room temperature, the reaction mixture was treated with water. The aqueous solution was treated with toluene to... 

Into a 500 ml. round-bottomed flask, fitted with a reflux condenser, place 42 g. of potassium hydroxide pellets and 120 g. (152 ml.) of absolute ethyl alcohol. Heat under reflux for 1 hour. Allow to cool and decant the liquid from the residual solid into another dry 500 ml. flask add 57 g. (45 ml.) of A.R. carbon dtsulphide slowly and with constant shaking. Filter the resulting almost solid mass, after cooling in ice, on a sintered glass funnel at the pump, and wash it with two 25 ml. portions of ether (sp. gr. 0-720), followed by 25 ml. of anhydrous ether. Dry the potassium ethyl xanthate in a vacuum desiccator over silica gel. The yield is 74 g. If desired, it ma be recrystallised from absolute ethyl alcohol, but this is usually unneceasary. 

For the manufacturiag of potassium ethyl xanthate, 400% excess of alcohol and equimolar quantities of 50 wt % aqueous potassium hydroxide and carbon disulfide were used (77). After 30 min at 40°C, the mixture was vacuum dmm dried. The product was obtained ia near quantitative yield and assayed at 95%. It is claimed that potassium amyl xanthate can be made with almost the same ratio of reactants and 80 wt % caustic potash (78). 

Ethyl Phenylmalonate (16, 33) By condensing ethyl phenylacetate with ethyl carbonate using a sodium-potassium alloy. Skinner, J. Am. Chem. Soc. 59, 322... 

Kiba et al. propose the separation of technetium from rheniiun by carbon tetrachloride extraction using potassium ethyl xanthate as reducing agent. 

Ethyl pyridine-2-acetate and ethyl 6-methylpyridine-2-acetate have previously been prepared by carboxylation of the lithio derivatives of a-picoline and lutidine, respectively. Use of ethyl carbonate to acylate the organometallic derivative avoids the intermediacy of the (unstable) carboxylic acid, and the yields are better. In the present procedure potassium amide is used as the metalating agent the submitters report that the same esters may be formed by metalation with sodium amide (43% yield) or with w-butyllithium (39% yield). The latter conditions also yield an appreciable amount of the acid (which decarboxylates). 

Previous preparations of 2-naphthalenethiol have included reduction of 2-naphthylsulfonyl chloride with zinc and acid4,5 or phosphorus and iodine.6-7 Alternatively, 2-naphthyldia-zonium chloride has been converted to the thiol using potassium ethyl xanthate and sodium carbonate.8 1 2 3 4... 

Apart from the reaction of diazomethane with benzoyl chloride,5-6 diazoacetophenone has been prepared by the reaction of 2-aminoacetophenone hydrochloride with sodium nitrite,7 from the mixed anhydride of benzoic acid and ethyl carbonate with diazomethane,8 from benzoyl chloride and potassium methyldiazotate,9 by treating the enamine formed from 2-formylacetophenone and N-methylaniline with p-toluenesulfonyl azide,10 and from the reaction of the sodium enolate of 2-formylacetophenone with p-toluenesulfonyl azide.11... 

Clavulanic acid may be extracted from the culture medium. Normally the cells of the Streptomyces clavuligerus are first removed from culture medium by filtration or centrifugation. Then clavulanic acid is extracted into an organic solvent, for example, n-butanol or ethyl acetate, or n-butyl acetate, or methyl isobutyl ketone. Then n-butanol fraction are treated with new aqueous phase using potassium hydrogen carbonate and then this aqueous phase is washed with n-butanol. This aqueous extract, after separation of the phases, is concentrated under reduced pressure. Freeze-drying at -20°C may also be... 

In the studies of the synthesis of the ansamycin antibiotic rifamycin S (13S), Corey and Clark [76] found numerous attempts to effect the lactam closure of the linear precursor 132 to 134 uniformly unsuccessful under a variety of experimental conditions, e.g. via activated ester with imidazole and mixed benzoic anhydride. The crux of the problem was associated with the quinone system which so deactivates the amino group to prevent its attachment to mildly activated carboxylic derivatives. Cyclization was achieved after conversion of the quinone system to the hydroquinone system. Thus, as shown in Scheme 45, treatment of 132 with 10 equiv of isobutyl chloroformate and 1 eqtuv of triethylamine at 23 °C produced the corresponding mixed carbonic anhydride in 95% yield. The quinone C=C bond was reduced by hydrogenation with Lindlar catalyst at low temperature. A cold solution of the hydroquinone was added over 2 h to THF at 50 °C and stirred for an additional 12 h at the same temperature. Oxidation with aqueous potassium ferricyanide afforded the cyclic product 134 in 80% yield. Kishi and coworkers [73] gained a similar result by using mixed ethyl carbonic anhydride. 

The replacement of an amino group by a mercapto group on an aromatic nucleus is effected by treating the diazotized amine with potassium ethyl xanthate and hydrolyzing the resulting aryl ethyl xanthate (Leuckart). Yields of 40-80% are reported for thiophenols containing methyl, halo, and methoxyl groups. Potassium ethyl xanthate is readily prepared from alcoholic potassium hydroxide and carbon disulfide. ... 

One hundred grams of crushed ice is added to a solution of 53 g. (0.50 mole) of o-toluidine in 97 g. of concentrated hydrochloric acid. The resulting mixture is diazotized by the addition of a solution of 36 g. (0.52 mole) of sodium nitrite in 60 g. of water. The temperature of the reaction mixture is maintained below 2° during this operation. A solution of 120 g. (0.75 mole) of potassium ethyl xanthate in 150 ml. of water is heated to 40° and stirred while the solution of the diazonium salt is added dropwise. The temperature is not allowed to rise above 45°. The cooled mixture is extracted with ether, and the ethereal solution is washed with 10% aqueous sodium carbonate, then with water. After the solution has been dried over calcium chloride. 

Analogous methods lead to benzimidazolethiones when o-phenylene-diamine.s arc treated with carbon disulfide, ihiophosgene, l.l -thiocarbonyldi-imidazolc, thioureas, thiocyanates or potassium ethyl xanthate [123, 126-129]. The reactions with carbon disulfide take place in basic media, e.g. with KOH or pyridine. Again, microwave irradiation offers advantages 1123]. 

The 4,5-di(thien-3-yl)-l,3-dithiol-2-one 517 was prepared from the thiophene-3-carboxaldehyde 513 which was first converted into the benzoin derivative 514. Subsequent Appel s reaction of the latter with PPhs and carbon tetrachloride afforded the chloride 515, which underwent reaction with potassium ethyl xanthate to form 516, from which the l,3-dithiol-2-one derivative 517 was obtained in overall 50% yield from 514 upon treatment with HBr/ AcOH (Scheme 74). The unsymmetrical 522 was prepared by transformation of the carboxylic acid 518 to the corresponding acid chloride which took part in a Friedel-Grafts reaction with thiophene in the presence of AIGI3 to... 

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