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Potassium cyanide conversion

The most important reaction of the sulphonic acids is their conversion into phenols by fusion with caustic alkalis. When they are fused with potassium cyanide, nitriles are obtained, e.g. benzonitriie from ben-zenesulphonic acid. [Pg.378]

Dry potassium cyanide in sealed containers is stable for many years. An aqueous solution of potassium cyanide is slowly converted to ammonia and potassium formate the decomposition rate accelerates with increasing temperature. However, at comparable temperatures the rate of conversion is far lower than that for sodium cyanide only about 25% as great. [Pg.385]

Reagent grade potassium cyanide was purchased from Matheson, Coleman and Bell, and dried at IIB C (0.5 itm) for 24 hr. The checkers found it necessary to use newly purchased potassium cyanide. The use of potassium cyanide which was several years old gave incomplete reaction even at extended reaction times. The large excess of potassium cyanide is used simply to obtain convenient reaction times. For comparison, use of 1.5 equiv of KCN gave 38% conversion under conditions where 3 equiv produced 100% conversion. [Pg.197]

Schemes 15 and 16 summarize the syntheses of intermediates that represent rings A and D of vitamin Bi2 by the Eschenmoser group. Treatment of lactam/lactone 51, the precursor to B-ring intermediate 8 (whose synthesis has already been described, see Scheme 8), with potassium cyanide in methanol induces cleavage of the y-lac-tone ring and furnishes intermediate 76 after esterification of the newly formed acetic acid chain with diazomethane. Intermediate 76 is produced as a mixture of diastereomers, epimeric at the newly formed stereocenter, in a yield exceeding 95%. Selective conversion of the lactam carbonyl in 76 into the corresponding thiolactam... Schemes 15 and 16 summarize the syntheses of intermediates that represent rings A and D of vitamin Bi2 by the Eschenmoser group. Treatment of lactam/lactone 51, the precursor to B-ring intermediate 8 (whose synthesis has already been described, see Scheme 8), with potassium cyanide in methanol induces cleavage of the y-lac-tone ring and furnishes intermediate 76 after esterification of the newly formed acetic acid chain with diazomethane. Intermediate 76 is produced as a mixture of diastereomers, epimeric at the newly formed stereocenter, in a yield exceeding 95%. Selective conversion of the lactam carbonyl in 76 into the corresponding thiolactam...
Potassium cyanide, reaction with N,N-dimethylaminomethyl ferrocene methiodide to yield ferrocenyl-acetonitrile, 40, 45 Potassium ethoxide for conversion of... [Pg.64]

Sandmeyer s synthesis of aromatic nitriles is far more elegant than the removal of water from the ammonium salts of carboxylic acids, which latter reaction is also applicable to benzene derivatives. In particular, the former synthesis permits of the preparation of carboxylic acids via the nitriles, and so provides a complete substitute for Kolbe s synthesis (alkyl halide and potassium cyanide), which is inapplicable to aromatic compounds. The simplest example is the conversion of aniline into benzoic add. The converse transformation is Hofmann s degradation (benzamide aniline, see p. 152). [Pg.293]

Another approach for determination of the absolute configuration of the monosaccharide components69 involves their interaction with radioactive potassium cyanide and conversion of the products into a mixture of heptonamides. Isotopic-dilution experiments showed the presence of D-gfi/cero-L-manno-heptonamide, thus establishing the D-galacto configuration of the starting hexose. [Pg.320]

In addition to their thermodynamic stability, complexes of macrocyclic ligands are also kinetically stable with respect to the loss of metal ion. It is often very difficult (if not impossible) to remove a metal from a macrocyclic complex. Conversely, the principle of microscopic reversibility means that it is equally difficult to form the macrocyclic complexes from a metal ion and the free macrocycle. We saw earlier that it was possible to reduce co-ordinated imine macrocycles to amine macrocyclic complexes in order to remove the nickel from the cyclam complex that is formed, prolonged reaction with hot potassium cyanide solution is needed (Fig. 6-24). [Pg.157]

The palladium-catalyzed, microwave-assisted conversion of 3-bromopyridine to 3-cyanopyridine using zinc cyanide in dimethylformamide (DMF) has been reported <2000JOC7984>. Substoichiometric quantities of copper or zinc species improve both conversion rate and efficiency of Pd-catalyzed cyanation reactions <1998JOC8224>. A modification of this procedure uses a heterogeneous catalyst prepared from a polymer-supported triphenylphosphine resin and Pd(OAc)2 the nitriles were obtained from halopyridines in high yields <2004TL8895>. The successful cyanation of 3-chloropyridine is observed with potassium cyanide in the presence of palladium catalysts and tetramethylethylenediamine (TMEDA) as a co-catalyst <2001TL6707>. [Pg.65]

Volumetric Methods.—Nickel may be conveniently estimated volu-metrically in the absence of cobalt, copper, silver, gold, and the platinum metals by means of potassium cyanide.4 The solution containing the nickel is, if acid, neutralised with ammonia and some ammonium sulphate is added to render the indicator more sensitive. A little ammonia is now added, and a few drops of potassium iodide and silver nitrate. The solution becomes turbid in consequence of the precipitation of silver iodide. The liquid is now titrated with potassium cyanide solution until the turbidity just disappears. The reaction consists in converting the nickel salt into the double cyanide, Ni(CN)a.2KCN, after which any excess of potassium cyanide attacks the silver iodide, yielding the soluble double cyanide, AgCN.KCN. The disappearance of the turbidity therefore indicates the complete conversion of the nickel salt. A slight correction is necessary for the silver introduced. [Pg.135]

The formation of cyano ketones by this method is illustrated by the conversion of phenacyl halides to the corresponding nitriles. Ring closure to cyclopropane derivatives is a side reaction which has been encountered with y-halo ketones. Benzalacetophenone dibromide is converted by alcoholic potassium cyanide to the fi-cyaao ketone, the a-halogen atom being reduced. Several a-chloro ketones have been found to yield a-cyano epoxides. ... [Pg.748]

This can be explained by the fact that these syntheses all consist of two separate steps. In the first step the molybdenum is reduced in acid medium from the +6 to the +5 oxidation state. In the second step potassium cyanide is introduced, and formation of the molybdenum (IV) cyanide complex takes place in alkaline medium as a result of disproportionation of the molybdenum (V) into the +4 and -1-6 oxidation states. As a result of the disproportionation, the conversion cannot possibly exceed 50%. One method described in the literature is not subject to this limitation however, the procedure is rather lengthy and complex. ... [Pg.54]

The immobilized silacrovm wets added to a two phase mixture containing concentrated aqueous potassium cyanide and substrate dissolved in acetonitrile. The mixture was stirred at 600-1000 rpm. Results are shown in Table IV. The immobilized sila-crown catalyzed cyanide displacement reactions in the three cases. The conversion of benzyl chloride to benzyl cyanide proceeded to 100% conversion, similar to the soluble silacrovm. [Pg.288]

The conversion of benzyl chloride to benzyl cyanide proceeded further than the soluble silacrovm. There is insufficient data to determine whether this is a general phenomenon. It has been pointed out by other workers7 that silica provides an adsorptive surface that can provide assistance in phase transfer. The reaction of potassium cyanide with allyl bromide under liquid/liquid phase transfer conditions produced a mixture of allyl cyanide and crotononitrile. This may be compared to the cataysis exhibited by another new phase transfer catalyst, immobilized trimethoxysilyloctyltributylammonium bromide, which produced only allyl cyanide. [Pg.288]

A concentrated aqueous solution of potassium cyanide was prepared containing lg of KCN in 2ml of solution. Q.05M of organic reactant was combined with 0.1M of aqueous KCN and 2g of silacrown treated porous glass. The reaction mixtures were stirred at 600-1000 rpm with a magnetic stirrer. Product conversion was determined by gas chromatography. [Pg.291]

Mix 10 grammes of benzaldehyde with 20 grammes of alcohol and treat the mixture with a solution of 2 grammes of potassium cyanide and 5 c.c. of water. Boil on the water-bath for one hour (reflux condenser). The hot solution is poured into a beaker and allowed to cool slowly the crystals separating out are filtered off, washed with alcohol, and dried on the water-bath. For conversion into benzil (see next preparation), they need not be recrystallised. In order to obtain perfectly pure benzoin, a small portion of the crude product is recrystallised from a little alcohol in a test-tube. Melting-point, 1340- Yield, about 90% of the theory. [Pg.276]

In contrast to allyl halides substituted with one ASG, the cyclopropanation reaction proceeds relatively smoothly when a second ASG is present. Generally, the best results are obtained with sodium borohydride, sodium cyanide, potassium cyanide, and the sodium salts of alcohols or thiols as the nucleophilic species (Table 22, entries 3-26). Even spiroalkanes can be synthesized with the nucleophiles described above (Table 23). Examples illustrating this route are the conversion of a tetracyclic enamino ester with potassium cyanide to the corresponding electrophilic cyclopropane 2, and the facile one-pot synthesis of 1,1 -bis(hydroxymethyl)cyclo-propanes 3 by reduction of halogenated alkylidene malonates with lithium aluminium hydride. ... [Pg.89]


See other pages where Potassium cyanide conversion is mentioned: [Pg.11]    [Pg.342]    [Pg.339]    [Pg.280]    [Pg.259]    [Pg.268]    [Pg.328]    [Pg.581]    [Pg.583]    [Pg.1701]    [Pg.125]    [Pg.101]    [Pg.405]    [Pg.90]    [Pg.437]    [Pg.415]    [Pg.224]    [Pg.289]    [Pg.414]    [Pg.169]    [Pg.532]    [Pg.259]    [Pg.414]    [Pg.9]    [Pg.362]    [Pg.252]    [Pg.402]    [Pg.259]    [Pg.522]    [Pg.211]   


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