Hydrazides decomposition

The conversion of esters to hydrazides and of hydrazides to the sulfonyl derivatives occurs in good yield in the McFadyen-Stevens synthesis, but the decomposition of sulfonyl derivatives gives low yields of the desired products, for example, thiazole hydrazide (28) with 10% excess of PhSOjCl in pyridine gave a 75% yield of l-phenylsulfonyl-2-(4-methyl-5-thiazo ecarbonyl)hydrazine (29) (66). The Newman-Caflish modification of the McFadyen-Stevens synthesis gave 37% 4-methyl-5-thiazole-carboxaldehyde (30) (Scheme 27). 

A most widely used decomposable chemical blowing agent is azodicarbonamide. Its decomposition temperature and rate of evolution of gaseous components are greatly influenced by the stabilizers containing zinc. Lead and cadmium are considered moderate activators for, -oxybis benzenesulfonyl hydrazide (OBSH). OBSH can also be used as a blowing agent for PVC foams. 

A useful reaction in early preparations of parent pyridopyrimidines was the McFadyen-Stevens decomposition of tosyl hydrazides, e.g. (93) -> (3) (62JCS4094). 

Oxybis(benzenesulphono hydrazide) (IV) Hydrazide N2,H20 150 120-180 Faster decomposition rate than azodicarbonamide but low blowing power limits use. 

Solution studies of the complexes outlined in Table 3 are in general agreement that they remain aggregated in solution, with the most common form being dimers.325 Solution studies of 300 in arene solvent indicate that at least two independent aggregates coexist.322 The most likely scenario from the data available is that a dimer-hexamer equilibrium is present in solution. Gas-phase studies of the hydrazides have proved to be problematic due to decomposition of the complexes on volatilization. 

ABH is relatively insoluble when directly added to water or buffer, and therefore it should be pre-dissolved in DMSO prior to addition of an aliquot to an aqueous reaction medium. Stock solutions at a concentration of 50 mM ABH in DMSO work well. Since both reactive groups on ABH are stable in aqueous environments as long as the solution is protected from light, a secondary stock solution may be made from the initial organic preparation by adding an aliquot to the hydrazide reaction buffer (0.1 M sodium acetate, pH 5.5 O Shannessy et al., 1984 O Shannessy and Quarles, 1985). Make a 1 10 dilution of the ABH/DMSO solution in the reaction buffer. This solution may be stored in the dark at 4°C without decomposition. 

Texas Red hydrazide is soluble in DMF and may be dissolved as a concentrated stock solution in this solvent prior to the addition of a small aliquot to an aqueous reaction medium. The solid and all solutions made from it must be protected from light to avoid photo-decomposition. Prepare the stock solution fresh immediately before use. A suggested protocol on the use of this fluorescent probe may be obtained by following the method outlined for fluorescein-5-thi-osemicarbazide in Section 1 of this chapter. Optimization may be necessary to achieve the best level of fluorescent modification (F/P ratio) for a particular application. 

Chemical blowing agents undergo decomposition at the vulcanisation temperature to form a gaseous species such as nitrogen or carbon dioxide, e.g., azo compounds, nitroso compounds, sulphonyl hydrazide compounds, ammonium carbonate, ammonium bicarbonate and sodium bicarbonate. 

Special review articles published since 1968 on these topics are one by E. H. White and D. F. Roswell 2> on hydrazide chemiluminescence M. M. Rauhut 3) on the chemiluminescence of concerted peroxide-decomposition reactions and D. M. Hercules 4 5> on chemiluminescence from electron-transfer reactions. The rapid development in these special fields justifies a further attempt to depict the current status. Results of bioluminescence research will not be included in this article except for a few special cases, e.g. enzyme-catalyzed chemiluminescence of luminol, and firefly bioluminescence 6>. 

The emission spectra match the fluorescence of the corresponding acid. Methane was detected as a major product in the chemiluminescent oxidation of 57 a and it was suggested that it resulted from the decomposition of methyl-diimine formed after dehydrogenation of the hydrazide 57a ... 

The reaction of Curtius, which is especially to be preferred in the case of the higher members on account of the favourable solubilities of the intermediate products, involves as its first stage the preparation of the hydrazide from an ester (or acid chloride). The hydrazide is then converted, usually very readily, by the action of nitrous acid into the azide. In many cases it is more convenient to prepare the azide by treating an acid chloride with sodium azide previously activated with hydrazine hydrate.1 Azides easily undergo thermal decomposition, the two azo nitrogen atoms being eliminated as elementary nitrogen. In this way, however, the same radicle is formed as was invoked above to explain the Hofmann reaction ... 

Since diimide exists as a transient intermediate and cannot be isolated under normal conditions, procedures for reduction by diimide necessarily involve generation of the reagent in situ1 1 11. Diimide can be generated by (i) oxidation of hydrazine, (ii) acid decomposition of azodicarboxylate salts and (iii) thermal or base-catalyzed decomposition of substituted benzenesulfonyl hydrazides. 

The hydrazide of 2,2-diphenyl-3-hydroxypropanoic acid was reduced with lithium aluminum hydride in 7V-ethylmorpholine at 100° to 3-amino-2,2-di-phenylpropanol in 72.5% yield [1145], Much more useful is reduction of N-arenesulfonylhydrazides of acids to aldehydes McFadyen-Stevens reduction) [284, 285] based on an alkali-catalyzed thermal decomposition according to Scheme 174. 

DNPT)) were studied using a gas evolution apparatus. The decomposition temperature of ADC decreased with both DNPT and 4,4-oxybis(benzenesulphonyl hydrazide) (OBSH) blending and this affected the structure and properties of the resulting foams. Using a tube mould for an extrudate to vulcanise the NR/EPDM extradate in a hot air oven was found to control the expansion and foam dimensions. The NR compositions affected the foam structure and properties. 16 refs. 

The carbon-carbon double bond can be reduced by diimide prepared in solution in a number of ways.34 183,184 Oxidation of hydrazine with oxygen (air) or H202 in the presence of a catalytic amount of Cu(II) ion was the first method to generate and use diimide in hydrogenation.183-185 Acid-catalyzed decomposition of alkali azido-dicarboxylates,185,186 as well as thermal or base-catalyzed decomposition of aromatic sulfonyl hydrazides,183,184 are also useful methods for preparing the diimide reducing agent. 

Malic and citric acids have been adequately identified from molasses as their crystalline hydrazides.119 It is probable that at least the former is a normal juice constituent. Lactic acid was identified as its zinc salt in molasses119 it arises from bacterial action. Formic acid is present119 it probably has an origin, at least in part, in sugar decomposition. Acetic and propionic acids are components and their amounts serve as a rough index of the activity of the microorganisms introduced into the molasses. The microbial count of cane juice, molasses and related products has been determined (Table IV).190... 

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