Hydrazodicarboxylate

In the examples above the sulfur dichloride links together two carbon atoms. It is equally possible to link two nitrogen atoms, as illustrated by the formation of a 1,4,2,3,5,6-dithiatetrazine (25) from a hydrazodicarboxyl-ate ester.30 Amidinium salts afford 1,2,3,5-dithiazolium salts (26).31... 

The reaction of a pyridazine, 5 dicarboxylic acid derivative with hydrazine remains a favored approach for the preparation of pyridazino[4,5-4 pyridazines <2000TL2863, 2002JCCS217>, and di- /t-butyl hydrazodicarboxylate has been used as a hydrazine substitute in the presence of perhydro derivatives, as illustrated in Equation (6) <1993JPC13408>. 

After the addition of the reactants is complete, the reaction is allowed to stir for an additional 30 min while the solution warms to room temperature. The reaction mixture is then transferred to a separatory funnel. The viscous organic bottom layer is separated from the aqueous layer and is dissolved in 200 mL of ether. The reaction vessel is washed with 100 mL of ether, and this ether portion is used to extract further the aqueous layer. The ether layers are combined, dried over magnesium sulfate, and filtered, and the solvent is removed under reduced pressure. The viscous oil is allowed to crystallize in an ice bath (0°C). The crystals are collected on a Buchner funnel, washed with 500 mL of water, and dried in a vacuum desiccator at 0.5 mm for 48 hr. 80.8 g (93%) of white crystalline bis(2,2,2-trichloroethyl) hydrazodicarboxylate (mp 85-89°C) is obtained. This material is sufficiently pure for the next preparation. However, further purification can be achieved using an Abderhalden drying apparatus (refluxing 95% EtOH for 12 hr at 0.05 mm MgS04 desiccant). Material purified in this way melted at 96.5-97.5°C (Notes 4 and 5). 

In a 500-mL, three-necked flask equipped with mechanical stirrer, thermometer, pressure-equalizing dropping funnel, and gas outlet tube is added 78.55 g (0.21 mol) of bis(2,2,2-trichloroethyl) hydrazodicarboxylate dissolved in 180 mL of chloroform (Note 6). The solution is cooled to 0°C and 53.2 mL (1.26 mol) of fuming nitric acid (Notes 7 and 8) is added so that the temperature of the solution does not rise above 5°C. The reaction mixture is then allowed to warm slowly to room temperature over 4 hr (Note 9). After an additional 2 hr at room temperature, the material is transferred to and shaken in a 1-L separatory funnel half filled... 

Bis(2,2,2-trichloroethyl) azodicarboxylate has been prepared by oxidation of bis(2,2,2-trichloroethyl) hydrazodicarboxylate with dinitrogen tetroxide.3... 

A. Bis(2,2,2-trichloroethyl) hydrazodicarboxylate. In a 500-mL, three-necked flask equipped with mechanical stirrer, thermometer, and 250-mL and 125-mL dropping funnels (Note 1) is placed a solution of 13.34 g (0.23 mol) of 64% hydrazine hydrate (Note 2) in 60 mL of 95% ethanol. The reaction flask is cooled in an ice bath and 96 g (0.46 mol) of 2,2,2-trichloroeihyl chloroformate (Note 3) is added dropwise so that... 

Both saturated and benzylic alcohols are dehydrogenated by refluxing with diethyl azodicarboxylate in benzene for 10 h. The azodicarboxylate is converted into hydrazodicarboxylate, while the alcohols give ketones in 51-87% yields [977. ... 

Diethyl and di-ter/-butyl hydrazodicarboxylate are dehydrogenated to diethyl- and di-tert-butylazodicarboxylate, respectively, by nitric acid [1184] and by iV-bromosuccinimide [1185] (equation 493). 

It is decomposed by hydrochloric acid into ethyl hydrazodicarboxyl-ate, mercuric chloride, carbon monoxide, and alcohol by piperidine into ethyl hydrazodiearboxylate, mercury, and piperylurethane by bromine into ctliyl azodicarboxylate, mercuric bromide, and ethyl bromoforni ate. 

A. Ethyl hydrazodicarboxylate. In a 2-1. three-necked flask, equipped with a mechanical stirrer, two 500-ml. dropping funnels, and a thermometer (Note 1), is placed a solution of 59 g. (1 mole) of 85% hydrazine hydrate in 500 ml. of 95% ethanol. The reaction flask is cooled by means of an ice bath. When the temperature of the solution has dropped to 10°, 217 g. (2 moles) of ethyl chloroformate is added dropwise with stirring at a rate sufficient to maintain the temperature between 15° and 20°. After one-half of the ethyl chloroformate has been introduced, a solution of 106 g. (1 mole) of sodiiun carbonate in 500 ml. of water is added dropwise simultaneously with the remaining ethyl chloroformate. The addition of these two reactants is regulated so that the temperature does not rise above 20° and so that the addition of the chloroformate is completed slightly in advance of the sodium carbonate in order to ensure a slight excess of ethyl chloroformate in the reaction mixture at all times. 

B. Ethyl azodicarboxylate. A mixture of 100 g. (0.57 mole) of ethyl hydrazodicarboxylate, 500 ml. of benzene, and 500 ml. of water is placed in 2-1. three-necked flask equipped with a mechanical stirrer and a gas inlet tube. The flask and contents are tared, the flask is placed in an ice bath, and a slow stream of chlorine is bubbled into the mixture with stirring. The temperature is maintained below 15°, and chlorine is introduced until the increase in weight amounts to 50-55 g. (Note 3). The flow of chlorine is stopped and the reaction mixture is stirred imtil a clear, orange-colored benzene layer forms when the mixture is allowed to settle. 

Ethyl hydrazodicarboxylate may be purified by crystallization from dilute ethanol m.p. 134-135°. 

Ethyl hydrazodicarboxylate can be prepared by the reaction of ethyl chloroformate with hydrazine hydrate or hydrazine sulfate in the presence of potassium hydroxide. It can be prepared also by the treatment of symmetrical hydrazinedicarboxylic acid diazide with ethyl alcohol. ... 

Ethyl azodicarboxylate can be prepared by treating ethyl hydrazodicarboxylate with concentrated nitric acid or a mixture of concentrated and fuming nitric acid. ... 

New Diels-Alder adducts of thebaine with aromatic nitroso-compounds of structure (118 R = H, Me, Cl) have been prepared. These are unstable and can be hydrolysed to 14-aryIhydroxylaminocodeinones (119), which can be reduced to derivatives of the hitherto inaccessible 14-aminodihydrocodeinone (120). The base (119 R = H) is susceptible to base-catalysed displacement of the oxide bridge, the product being the 5,14-bridged thebainone derivative (121). ° The reaction between thebaine and excess of ethyl azodicarboxylate involves Diels-Alder addition and addition of the N-CH3 group to a second molecule of azo-ester. The primary product (122) has not been isolated pure, but yields ethyl hydrazodicarboxylate and the substituted codeinone (123) on hydrolysis. ... 

Oxidation of various nitrogen compounds. Primary aromatic amines are oxidized slowly to azobenzenes in yields on the order of 40-50%. Esters of hydrazodicarboxylic acid are oxidized rapidly and in high yield in refluxing... 

Engineering resins and their blends have been foamed using mainly chemical foaming agents, e.g., hydrazodicarboxylates, benzazimides or 5-phenyltetrazole. However, products of decom-... 

Ethyl hydrazinecarboxylate, 24, 58 Ethyl hydrazodicarboxylate, 28, 58 Ethyl hydrogen adipate, 25, 21 Ethyl hydrogen sebacate, 21, 48 26, 21 electrolysis of, 21, 48 Ethyl 4-hydro benzoate, 29, 35 Ethyl a-ISOPROPYLACETOACETATE, 27, 35... 

Ring closures via N,N -dicarbalkoxy-N-methylenehydrazinium salts Cyclic hydrazodicarboxylic acid esters... 

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