Hydrazines, preparation

Yield of 1-alkjd-diaziridine, calculated on the diazirine which was not isolated. A ield of the alkyl hydrazine prepared by hydrolysis of the l-alkyl-diaziridine (calculated on diazirine). 

Hydrazine is an endothermic compound and the vapour is exceptionally hazardous in that once it is ignited, it will continue to bum by exothermic decomposition in complete absence of air or other oxidant [1]. Distillation of anhydrous hydrazine (prepared by dehydrating hydrazine hydrate with solid sodium... 

A variety of one-carbon cyclizing agents have been used (71JOC10) to prepare 3-substituted l,3-thiazolo[2,3-c] 1,2,4-triazoles (111) from 2-hydrazino-l,3-thiazoles (110). The acid hydrazides (113) of these hydrazines, prepared either directly from 110 and carboxylic acid derivatives or indirectly from 1-acylthiosemicarbazides (112) and a-haloketones, also undergo facile dehydrative cydization to 111. [71JOC10 78JHC401 ... 

Excellent reviews of azeotropic and extractive distillation, oxo process, polymers, fractionating trays, separation by crystallization radioisotopes, radiation processing, detergents, hydrazine preparation, liquid thermal diffusion, isomerization, acetylene manufacture, etc. 

Solid-liquid phase-transfer-catalyzed phosphorylation of hydrazine, preparation of dialkyl phosphorohydrazidates and N,N -bis[dialkoxyphosphoryl]hydrazines. 

C HgNjOjS. Colourless needles, with iH20. Prepared by reducing diazotized sulphanilic acid with an excess of sodium sulphite. It is a typical hydrazine in its reactions with ketones, and with acetoacetic ester. The latter reaction gives rise to the tartrazine dyestuffs, and is much used commercially. 

Hydrazine is prepared, anhydrous and in good yield, by glow discharge electrolysis of liquid ammonia a platinum cathode is immersed in liquid and a platinum wire anode is mounted just... 

H—N—N=N. It is prepared by the oxidation of hydrazine in strongly acid solution the oxidising agent used is usually nitrous acid (i.e. sodium nitrite is added to the acid solution of hydrazine) ... 

This can be extracted from impure phosphine prepared by the action of sodium hydroxide on phosphorus. Unlike hydrazine, it has no basic properties. It is a powerful reducing agent and burns spontaneously in air, this reaction explaining why impure phosphine containing traces of diphosphane ignites spontaneously in air. 

Osazone formation. The preparation of glucosazone has already been given (p. 137). It may be carried out on a small scale by either of the following methods, according as (a) the phenyl hydrazine base, or (Z>) one of its salts, is used. 

Hydrazine hydrate of 60 per cent, and 100 per cent, are available commercially. The preparation from hydrazine sulphate is hardly worth while. 

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... 

The independent preparation of potassium phthabmide (from a solution of phthalimide in absolute ethanol and potassium hydroxide in 75 per cent, ethanol) may be avoided in many cases by boiling phthalimide with the halide in the presence of anhydrous potassium carbonate. The N-substituted phthalimide (I) is frequently cleav with difficulty this is often facilitated by reaction with hydrazine hydrate to give an intermediate product, which is easily decomposed by hydrochloric acid to 3deld the insoluble hydrazide of phthaUc acid (II) and the primary amine (III) ... 

The modified procedure involves refluxing the N-substituted phthaUmide in alcohol with an equivalent quantity of hydrazine hydrate, followed by removal of the alcohol and heating the residue with hydrochloric acid on a steam bath the phthalyl hydtazide produced is filtered off, leaving the amine hydrochloride in solution. The Gabriel synthesis has been employed in the preparation of a wide variety of amino compounds, including aliphatic amines and amino acids it provides an unequivocal synthesis of a pure primary amine. 

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 ... 

Suspend 35 g. of finely-powdered hydrazine sulphate in 125 ml. of hot water contained in a 400 ml. beaker, and add, with stirring, 118 g. of crystallised sodium acetate or 85 g. of potassium acetate. Boil the mixture for 5 minutes, cool to about 70°, add 80 ml. of rectified spirit, filter at the pump and wash with 80 ml. of hot rectified spirit. Keep the filtered hydrazine solution for the next stage in the preparation. 

The following alternative method of preparation is recommended. Dissolve 50 g. of purified 2 4-dinitrochlorobenzene (1) in 100 ml. of triethylene glycol (gentle warming nia be necessary alternatively, 125 ml. of warm diethylene glycol may be used) in a 600 ml. beaker and cool, with mechanical stirring, in an ice bath to 15-18°. Place 15 ml. of commercial 60-65 per cent, hydrazine solution in a small separatory funnel supported over the beaker. Add the hydrazine solution to the stirred solution in the beaker at such a rate that the temperature is maintained between 15° and 20° (20-30 minutes). When... 

Azines, Aldehydes react with hydrazine to yield azines the reaction cannot usually be arrested at the hydrazone stage. This reaction may be illustrated by the preparation of bevzalazine from benzaldehyde ... 

Dimethylpyrazole (III) may be prepared from acetylacetone (I) and hydrazine (II) (produced from hydrazine sulphate and aqueous alkali). The reaction may be represented as ... 

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... 

Pyridyl)hydrazine (Aldrich), 4-acetylpyridine (Acros), N,N,N -trimethylethylenediamine (Aldrich), methylrhenium trioxide (Aldrich), InQj (Aldrich), Cu(N0j)2-3H20 (Merck), Ni(N03)2-6Il20 (Merck), Yb(OTf)3(Fluka), Sc(OTf)3 (Fluka), 2-(aminomethyl)pyridine (Acros), benzylideneacetone (Aldrich), and chalcone (Aldrich) were of the highest purity available. Borane dimethyl sulfide (2M solution in THE) was obtained from Aldrich. Methyl vinyl ketone was distilled prior to use. Cyclopentadiene was prepared from its dimer immediately before use. (R)-l-acetyl-5-isopropoxy-3-pyrrolin-2-one (4.15) has been kindly provided by Prof H. Hiemstra (University of Amsterdam). 

This set of compounds is the most thoroughly studied among derivatives of 2-aminothiazole, thanks to the Beyer group. Heterocychzation methods are most commonly used for their preparation (see Chapter II and Refs. 37, 341, and 513-520). Reaction of 2-diazothiazoles (277) with organometallics provides another synthetic method (Scheme 1711 (521). 2-Hydrazinothiazoles may also be obtained by the action of hydrazine on 2-bromothiazoles (388) or on 2-mercaptothiazoles (522). 

Thiazolyloxy)propanediol-1.2-acetonide (198) has been prepared from 4-Br-thiazole (197) (Scheme 101) (440). Thiazolopyridazines (199) or thiazolooxazines (200) can be obtained from the 4-alkoxyderivalives (201) by treatment with hydrazine or hydroxylamine, respectively (Scheme 102) (441). 

Thiazolecarboxylic acid hydrazides are prepared by the same general methods used to prepare amides, that is, by treating acids, esters, amides, anhydrides, or acid halides with hydrazine or substitued hydrazines. For example, see Scheme 21 (92). The dihydrazides are obtained in the same way (88). With diethyl 2-chloro-4,5-thiazoledicarboxylate this reaction gives the mono hydr azide monoester of 2-hydrazine-4,5-... 

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