Reagents hydrazine

The usual carbonyl reagents (hydrazines, semicarbazone, hydroxyl-amine) do not give the normal derivatives, but lead to ring contraction and formation of pyrazoles or isoxazoles. However, a semicarbazone and an oxime of 2,6-diphenylpyrone has been obtained by Arndt et al., indirectly, through the intermediacy of the more reactive 4-thiopyrone. 

A nonexplosive form of hydrazine is used as the limiting reagent. Hydrazine is completely consumed after the addition of trifluoroacetate. In this manner, no hazardous waste containing hydrazine is generated. 

To negate the need to use the harsh and potentially hazardous deprotection reagent hydrazine, a superior alternative, which is particularly compatible for use in Fmoc/rBu solid phase synthesis, is Af-Fmoc-hydroxylamine, which can be used to effect a nucleophilic displacement reaction of 2-chlorotrityl chloride resin (33) (Figure 9). The resultant N-Fmoc-aminooxy-2-chlorotrityl polystyrene resin can be used for the synthesis of peptide hydroxamates as described in Protocol 8. 

Silver acetate has also been used as the oxidizing reagent Hydrazine analogues of the pyridone imines have been obtained as... 

Step 1. We can see topologically that the N2 unit in the reagent hydrazine, H2NNH2, has been added across the /3-dicarbonyl function (Chapter 23) in some way. Comparison of the respective molecular... 

Reagent A. Dissolve 0 5 g. of the powdered dinitropheny I hydrazine in a mixture of 80 ml. of concentrated hydrochloric acid and 100 ml. of distilled water by gently heating the mixture on a water-bath. Cool the solution and add 120 ml. of water. If necessary, filter the pale yellow solution. 

Prepare a solution of phenylhydrazine by dissolving 1 0 g. of phenyl-hydrazine hydrochloride and 1 5 g. of crystallised sodium acetate in 10 ml. of water if the resulting solution is turbid, filter. Add a solution of 0 5 ml. of cycZohexanone in 8 ml. of water to the reagent... 

This method cannot be applied to polynitro amines, since these are so weakly basic that they can be diazotised only under special conditions in strongly acidic solutions. In such cases use may, however, be made of the mobility oonfared upon halogen atoms by the presence of nitro groups in the orlko and para positions. Thus the valuable reagent 2 4-dinitrophenylhydrazine is readily prepared by the condensation of 2 4-dinitrochlorobenzene with hydrazine ... 

Aromatic ketones usually have relatively high boiling points, but distil with little or no decomposition. Many are solids. The vapours generally burn with a smoky flame. They react with the 2 4-dinitrophenyll hydrazine reagent (Section 111,74,/) or with the phenylhydrazine reagent... 

Method 2. Drop 10 g. of hydrazine hydrate (85 per cent, aqueous solution see Section 11,49,Id) into a hot solution of 35 g. of benzil (Section IV,126) in 70 ml. of alcohol with stirring. When about three-fourths of the hydrazine hydrate has been introduced, the product begins to separate. After all the reagent has been added, heat the solution under reflux for 5 minutes, cool to 0°, filter at the pump, and wash twice with 20 ml. portions of alcohol. The yield of benzil monohydrazone, m.p. 149-151° (decomp.), is almost quantitative. 

The acetone test reagent consists of a 0 1 per cent, solution of 2 4-dinitro-phenylhydrazine and is prepared as follows Dissolve 0-25 g. of 2 4-dinitrophenyl-hydrazine in 60 ml. of water and 42 ml. of concentrated hydrochloric acid by warming on a water bath cool the clear yellow solution and dilute to 250 ml. with water. The acetone test is considered negative when 5 ml. of the reagent and 4-5 drops of the distillate give no cloudiness or precipitate of acetone 2 4-dinitro-phenylhydrazone within 30 seconds. After a negative test is obtained, it is stron y recommended that the mixture in the flask be refluxed for 5-10 minutes with complete condensation and then to collect a few drops of distillate for another test. If no acetone is now detected, the reduction is complete. 

Girard s reagent T is carbohydrazidomethyltrimethylammonium chloride (I) and is prepared by the reaction of the quaternary ammonium salt formed from ethyl chloroacetate and trimethylamine with hydrazine hydrate in alco-hoUc solution ... 

Girard s reagent P , C5H5NCH2C0NHNH2 C1. In a 1-htre threenecked flask, equipped as in the previous preparation, place 200 ml. of absolute ethyl alcohol, 63 g. (64 -5 ml.) of pure anhydrous pyridine and 98 - 5 g. (84 5 ml.) of ethyl chloroacetate. Heat the mixture under reflux for 2-3 hours until the formation of the quaternary salt is complete acidify a small test-portion with dilute sulphuric acid it should dissolve completely and no odour of ethyl chloroacetate should be apparent. Cool the mixture in ice and salt. Replace the thermometer by a dropping funnel, and add a solution of 40 g. of 100 per cent, hydrazine hydrate in 60 ml. of absolute ethanol all at once. A vigorous exothermic reaction soon develops and is accompanied by vigorous effervescence. The pro duct separates almost immediately. When cold, filter with suction, wash... 

It must be remembered, however, that nitroso, azoxy and azo compounds (which are usually more highly coloured than nitro compounds) may bo reduced by zinc powder to the corresponding hydroxylamino, hydrazo and hydrazine compounds respectively, all of which reduco Tollen s reagent in the cold. 

The phthaloyl (Phth) derivatives of amines, formed from amines and N-ethoxy-carbonylphthalimide (G.H.L. Nefkens, 1960), are acid-resistant imides, which can be easily deblocked by nucleophilic reagents, most conveniently by hydrazine. 

Aluminum chloride [7446-70-0] is a useful catalyst in the reaction of aromatic amines with ethyleneknine (76). SoHd catalysts promote the reaction of ethyleneknine with ammonia in the gas phase to give ethylenediamine (77). Not only ammonia and amines, but also hydrazine [302-01-2] (78), hydrazoic acid [7782-79-8] (79—82), alkyl azidoformates (83), and acid amides, eg, sulfonamides (84) or 2,4-dioxopyrimidines (85), have been used as ring-opening reagents for ethyleneknine with nitrogen being the nucleophilic center (1). The 2-oxopiperazine skeleton has been synthesized from a-amino acid esters and ethyleneknine (86—89). 

The aminolysis of esters of pyrimidine occurs normally to yield amides. The reagent is commonly alcoholic ammonia or alcoholic amine, usually at room temperature for 20-24 hours, but occasionally under refiux aqueous amine or even undiluted amine are used sometimes. The process is exemplified in the conversion of methyl pyrimidine-5-carboxylate (193 R = Me) or its 4-isomer by methanolic ammonia at 25 °C into the amide (196) or pyrimidine-4-carboxamide, respectively (60MI21300), and in the butylaminolysis of butyl ttracil-6-carboxylate (butyl orotate) by ethanolic butylamine to give A-butyluracil-5-carboxamide (187) (60JOC1950). Hydrazides are made similarly from esters with ethanolic hydrazine hydrate. 

In forcing conditions with excess of reagents the 5,8-bis derivative was obtained in the above cases, with hydrazine and with sulfur nucleophiles. Other authors have also observed selective reactions in the pyrido[2,3-[Pg.242]

The decomposition of (536) with hydrogen sulfide yields pyrazole (76T1909). The 1-phosphorylpyrazoles (537) are suitable reagents for the phosphorylation of alcohols, amines, hydrazines and azides (76AG(E)378). 

The organic reagents are used extensively for determinations series of elements by different methods of analysis. We carry out the systematical investigation of organic derivatives of hydrazine as a reagent for determinations ion of metals by photometric and extractive-photometric methods or analysis, as well as methods of atomic absorption spectrometry. Series procedure determinations ion of metals in technical and environmental objects have been developed. 

Carboxymethyl)tr(methy(ammonlum chloride hydrazlde (Reagent T ). A cooled soKilion of ethyl chioroacetate (984 g, 6.65 mol) was treated with irimethylamine (200 g, 3.39 mol). After 12-24 h a second portion of trimethylamlne (200 g, 3.39 mol) was added. After complete consumption of ethyl chioroacetate, hydrazine (4C0 g) was added. The product was tillered and dryed under vacuum (H2SO4) to afford 1100 g of T (90%). 

Benzyl carbamates of pyrrole-type nitrogens can be cleaVfed with nucleophilic reagents such as hydrazine hydrogenation and HF treatment are also effective. ... 

---