Hydrazides and Azides

Special reactions of hydrazides and azides are illustrated by the conversion of the hydrazide (205) into the azide (206) by nitrous acid (60JOC1950) and thence into the urethane (207) by ethanol (64FES(19)105Q) the conversion of the same azide (206) into the N-alkylamide (208) by ethylamine the formation of the hydrazone (209) from acetaldehyde and the hydrazide (205) and the IV-acylation of the hydrazide (205) to give, for example, the formylhydrazide (210) (65FES(20)259). It is evident that there is an isocyanate intermediate between (206) and (207) such compounds have been isolated sometimes, e.g. (211). Several of the above reactions are involved in some Curtius degradations. 

A series of amides, hydrazides, and azides of phosphoric, phosphonic, and phosphinic acids were synthesized via the corresponding pyrazolides. 

Hydrolysis of the ester with 1 equivedent of NaOH, at room tempera-tme, gives the free acid. Its chloride, amide, hydrazide and azide are also knovm (62a). 

The conversion of hydrazides and azides to amines has been described in Section VIII. 1A(6). 

Curtius, T. Hydrazides and azides of organic acids. J. Prakt. Chem. 1894, 50, 275. 

Some bis (sulfonyl) hydrazides and azides are used as blowing agents in the plastics industry to obtain plastic foams. 

Chlorides, amides, esters, hydrazides, and azides of both of the isomeric methylfuroxancarboxylic acids have been described.93,94,96,260 The Curtius rearrangement of the azides has received particular attention.94 The cyano-... 

Enzymes have also been immobilized on collagen membrane after its stepwise modification to esters, hydrazides and azides [171]. Another method of enzyme electrode preparation consists of enzyme immobilization on polyacryl acid modified with p-nitroaniline and by a subsequent reduction of N02-groups with titanous chloride and following diazota-tion of resulting aromatic amines [150]. An enzyme electrode has also been prepared by the direct immobilization of an enzyme on the surface of a Pt-electrode which was formerly modified first with 3-aminopropyl triethoxysilane and secondly with glutaraldehyde and bovine serum albumin [172]. Enzymes can also be immobilized on p-benzoquinone-carbon paste[173] or on the graphite electrode after its activation with cyanuric chloride [174]. In a similar way an enzyme electrode has been prepared by using iridium diiodide electrode as a support [175]. 

Saturated Monocarboxylic Acids. Azides of saturated acids can be prepared almost equally well by reaction of the hydrazides with nitrous acid or by reaction of the acid chlorides with sodium azide. The latter method is superior for very low-molecular-weight acids, whose hydrazides and azides are difficult to extract from water by this method acetyl chloride is converted to methyl isocyanate through the azide in 60-72% yields. From lauroyl chloride, 86% of undecyl isocyanate is obtained by the sodium azide method. The reaction of acid an-... 

Nitro Groups. The Curtius d radation has been applied to only one nitro aliphatic azide ethyl nitrocyanoacetate is converted through its hydrazide and azide to a urethan. In the aromatic series, nitro-... 

A number of hydrazides and azides are listed in the column headed Starting Material. This is done when the structure of the precursor does not supply the identity of the hydrazide or azide obtained from it the precursor is then identified in a footnote. 

Chloro-3-nitrobenzenesulfonyl chloride 100, by condensation with hydrazine and sodium azide in the cold, afforded the corresponding hydrazide and azide which possessed herbicidal and flmgicidal activity. ... 

The two isomeric sulfonyl chlorides 134 and 135 were obtained in approximately equal amounts and the additional o-sulfonation may occur by an intramolecular mechanism. The chlorosulfonation of 2,6-dihalophenols by chlorosulfonic acid and the subsequent condensation of the 4-sulfonyl chloride with secondary amines, e.g. A/-methylaniline, yields sulfonjunides, like 3,5-dibromo-4-hydroxy-iV-methylphenylsulfonamide, which is an effective herbicide against wild oats. The various dichlorohydroxybenzenesulfonyl chlorides were converted into sulfonamides, hydrazides and azides for screening as novel biocides. o-Chlorophenol 136, by heating with chlorosulfonic acid (eight equivalents) at 100°C (1 hour), gave the 1,3-disulfonyl chloride 137 (59%) (Equation 44). 

The chemistry of sulfonyl hydrazides and azides has been discussed and both derivatives are used as blowing and cross-linking agents in the manufacture of foam rubbers and plastics. Some of the best hydrazides for this purpose are diphenyl ether-4,4 -disulfonyl hydrazide 59 together with the corresponding thio analogue 60. These hydrazides are respectively prepared by reaction of diphenyl ether or diphenyl sulfide with excess chlorosulfonic acid as previously described (Chapter 4, p 74, 76), followed by condensation of the appropriate disulfonyl chloride with excess hydrazine hydrate. ... 

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