Potassium reaction with hydrazones

The first step involves the formation of the (mesitylenesulfonyl)hydrazone A (mechanism Table 9.2), and the second comprises its reaction with potassium cyanide in acetonitrile. Being... 

Unsolvated potassium cyanide and hydrazone dissolve as the reactants are converted to the thermodynamically favored trans-nitrile. Shortly after all of the solid dissolves, a second solid precipitates from solution. This solid is presumed to be potassium mesitylenesulfinate and is usually accompanied by some foaming. An oversize flask used with efficient stirring keeps the reaction mixture from foaming into the condenser. 

Hydrazones. A useful procedure for preparation of hydrazones free from azines is exemplified by the preparation of acetone hydrazone.1 Acetone is first converted into acetone azine (b.p. 128-131°) by reaction with 100% hydrazine hydrate and potassium hydroxide this product is then converted into acetone hydrazone by reaction with anhydrous hydrazine2 and sodium hydroxide. 

Once again, new reagents for the direct conversion of aldehydes into nitriles have been reported,probably the most useful of which is the modified reductive cyanation procedure which now allows the preparation of nitriles from aldehydes with the addition of one C-atom (Scheme 20). An analogous procedure involves the reaction of potassium cyanide with the 2,4,6-tri-isopropylbenzenesulphonyl (trisyl) hydrazones of both aliphatic aldehydes and ketones (Scheme 21). 

An interesting approach to the synthesis of alkylphosphonates from A-tosylhydrazones has been presented (Scheme 4.63) [95]. The overall reaction was essentially a coupling reaction between the A-tosylhydrazones and a secondary phosphite. The catalyst system for this chemistry consisted of copper iodide along with a mineral base. For the hydra-zones derived from ketones, the most effective base was potassium carbonate however, for analogous reactions involving hydrazones derived from aldehydes, the most effective... 

To prepare fervenulin 4-oxides 12 or toxoflavine 4-oxides 146, it is convenient to use the reaction of l,3-dimethyl-2,4-dioxopyrimidin-6-yl hydrazone 147 or N-(3-methyl-2,4-dioxopyiimidin-6-yl) iV-methylhydrazone 148 with potassium nitrate in acetic acid [75CPB1885,76CPB338,76JCS(CC)658,82JHC1309,93CPB362]. Diethyl azodicarboxylate can be used instead of potassium nitrate [76JCS(P1 )713]. 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C—has been replaced almost completely by the modified procedure after Huang-Minlon The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tcrt-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

Lucifer Yellow CH is soluble in aqueous solution, and it should be stable for awhile if protected from light. The reagent is available as three different salts of the sulfonate groups. The ammonium salt of the fluorophore is soluble to a level of 9 percent in water, while the lithium and potassium salts have a solubility of 5 and 1 percent, respectively. A concentrated stock solution of the fluorophore may be prepared in water and an aliquot added to a buffered reaction medium to facilitate the transfer of small quantities. For aqueous reactions, a pH range of 5-9 will result in efficient hydrazone formation with aldehyde or ketone residues. 

The Neber reaction of 1 with the hydrazone salts in tetrahydrofuran containing potassium /m-butoxide gave 5 (77JOC2514), where azirines... 

An unusual one-pot intramolecular sulfoxide alkylation-elimination reaction was found by Gibson et al. <2001SL712>. These authors found that treatment of 459 with potassium bis-trimethylsilylamide resulted in a ring closure to 460 in acceptable yield. Furthermore, Batori and Messmer found an effective method for preparation of [l,2,3]triazolo[l,5- ]pyrimidinium salts <1994JHC1041> oxidative cyclization of hydrazones 461 by 2,4,4,6-tetrabromo-2,5-cyclohexadienone gave rise to the quaternary salts 462. Under certain reaction conditions, the formation of 6-bromo-salts 462 (R6 = Br) was also experienced. As neither the starting compound nor the quaternary triazolopyridinium salt underwent bromination in this position, the authors assumed that this bromination process occurred on one of the intermediates in the course of the above-mentioned cyclization reaction. 

The presence of the double bond (carbonyl group C 0) markedly determines the. chemical behavior of the aldehydes. The hydrogen atom connected directly to the carbonyl group is not easily displaced. The chemical properties of the aldehy des may be summarized by (1) they react with alcohols, with elimination of H2O, to form ace t i (2) they combine readily with HCN to form cyanohydrins, (3) they react with hydroxylamine to yield aldoximes (4) they react with hydrazine to form hydrazones (5) they can be oxidized lulu fatty acids, which contain die same [lumber of carbons as in the initial aldehyde 5) they can be reduced readily to form primary alcohols. When bcnzaldchydc is reduced with sodium amalgam and HjO, benzyl alcohol C,f l - -C f I Of I is obtained. The latter compound also may be obtained by treating benzaldehyde with a solution of cold KOH in which benzyl alcohol and potassium benzoate are produced. The latter reaction is known as Cannizzaro s reaction. 

Reaction of cyanide ion with an alkyl halide is often the most convenient route to a nitrile, but in those cases where the corresponding aldehyde or ketone is more readily available than the alkyl halide, the following procedure is very convenient. The carbonyl compound is first converted into its 2,4,6-triisopropyl-benzenesulphonyl hydrazone (1) (Expt 6.42 gives the method for the preparation of the reagent, TBSH), which without isolation is then reacted with potassium cyanide under gentle reflux.169... 

Aryl alkyl ketones are readily prepared by the Friedel-Crafts acylation process (see Section 6.11.1, p. 1006) and their Clemmensen reduction constitutes a more efficient procedure for the preparation of monoalkylbenzenes than the alternative direct Friedel-Crafts alkylation reaction (see below). Alternatively aldehydes and ketones may be reduced to the corresponding hydrocarbon by the Wolff-Kishner method which involves heating the corresponding hydrazone or semicarbazone with potassium hydroxide or with sodium ethoxide solution. 

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