Preparation of 65 Hydrazine

Preparation of Hydrazine. Assemble an apparatus as shown in Fig. 85b. Put an amount of potassium hydroxide into a two-neck flask provided with a reflux condenser such that there is a 2-3-mm layer of hydrazine hydrate over it. Cool the flask in a bath with ice and transfer the previously prepared hydrazine hydrate into it wear eye protection ). Pass a stream of dry nitrogen through the reaction mixture. Carefully heat the flask until the alkali dissolves completely, then cool the flask to room temperature, and, without stopping the nitrogen stream, replace the reflux condenser with a dephlegmator. Assemble an apparatus for fractional distillation (see Fig. 20) and distil off the anhydrous hydrazine in a nitrogen stream at 112-114 °C. 

Pour 2-3 ml of hydrazine on a watch glass and ignite it. The hydrazine should burn with a violet flame. If the sample of the obtained preparation does not ignite, freeze out the anhydrous hydrazine. To do this, put the receiver into a bath with ice. Pour the liquid off the precipitated crystals (what is the composition of the liquid and the crystals ), melt the crystals again, and repeat the operation. 

Again ignite a small amount of hydrazine. Perform a number of reactions characterizing the properties of hydrazine. (Propose these reactions yourself.) 

Preparation of 65% Hydrazine by Charles D. Hurd and C.W. Bennett Evanston, Illinois August 3,1928 

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Industrial preparation of hydrazine is based on this reaction of ammonia with an alkaline solution of sodium hypochlorite, known as the Raschig process introduced in 1907. 

The susceptibility of the sydnone ring to acid-catalyzed hydrolysis at elevated temperature is exploited for the preparation of hydrazines <2000MI227>. Primary amines are first converted to sydnones, which are then hydrolyzed to give hydrazines that may be isolated or reacted further without isolation <1996CHEC-II(4)165>. As masked hydrazines, 3-arylsydnones are firstly subjected to acid-catalyzed ring opening and then allowed to react further in situ with 2-(4-chlorophenyl)hydrazono-3-oxo-butyric acid to form substituted pyrazolidinones (Equation 2) <2005SC2169>. 

Other Applications. Hydioxykmine-O-sulfonic acid [295043-8] has many applications in the area of organic synthesis. The use of this material for organic transformations has heen thoroughly reviewed (125,126). The preparation of the acid involves the reaction of hydroxylamine [5470-11-1] with oleum in the presence of ammonium sulfate [7783-20-2] (127). The acid has found application in the preparation of hydrazines from amines, aliphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. It is also an important reagent in reductive deamination and specialty nitrile production. 

Preparation of Hydrazine Sulphate. Perform the experiment in a fume cupboard ). Preliminarily prepare a sodium hypochlorite solution. To do this, spill 100 g of ice (prepared from distilled water in the freezing chamber of a refrigerator) into a 300-ml flask and add a sodium hydroxide solution (dissolve 50 g of sodium hydroxide in 100 ml of water). Put the flask in a bath with ice. Pass chlorine during two hours into the cooled solution. When doing this, see that the temperature does not rise above 5 °C. 

Preparation of Hydrazine Hydrate. Assemble an apparatus as shown in Fig. 85a. Grind 30 g of solid potassium hydroxide into a powder in a porcelain mortar wear eye protection ). Add 30 g of hydrazine sulphate to the powder and thoroughly mix the reactants. 

Few examples of the preparation of hydrazines or hydroxylamines on insoluble supports have been reported (Table 10.17). Hydrazines have been prepared by the reduction of aromatic diazonium salts or /V-nitroso amines (prepared from secondary amines by treatment with tert-butyl nitrite [340]), and by the N-amination of support-bound amines (Entry 3, Table 10.17). The direct reduction of hydrazones with borane to yield hydrazines on solid phase has not been reported, and appears to be difficult because of the ease with which the N-N bond of hydrazines is cleaved by reducing agents [340]. 

Other Applications. Hydroxylainine-O-sulfonic acid has many applications in the area of organic synthesis. The acid has found application in the preparation of hydrazines from amines, aliphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. 

Preparation of Hydrazine Dihydrochloride from Benzalazine. One hundred and four grams of benzalazine (0.5 mol) is suspended in 400 ml. of water in a 4-1. round-bottom flask, and 80 ml. of concentrated hydrochloric acid added. The suspension is subjected to- steam distillation until no more benzaldehydef comes over in the distillate. 

Write the series of balanced equations for the preparation of hydrazine. 

Figure 3.84 Preparation of hydrazine using aqueous hydrogen peroxide.

Preparation of Hydrazine Perchlorate. Hydrazine perchlorate was prepared by titrating a solution of 85% hydrazine hydrate to a pH of 3.2 with 48% perchloric acid. This yielaed a stock solution which could be stored indefinitely. Hydrazine perchlorate was precipitated by pouring a volume of this solution into 5 volumes of 2-propanol at 0° C. The hydrazine perchlorate was filtered, washed with cold 2-propanol, and vacuum dried at 80° C. 

The one-electron oxidation of a secondary amine results in the formation of a secondary aminium ion which on deprotonation gives an aminyl radical (Scheme 1). The nature of the final products derived from these intermediates dqiends very much on the structure of the substrate and the reaction conditions. If the amine has a hydrogen atom on the a-carbon atom the major products usually result from deprotonation at this a-position. With aromatic secondary amines, products can result from coupling of the delocalized radicals at a ring carbon atom. The formal dimerization of aminyl radicals shown in Scheme 21 is therefore not often a useful method of preparation of hydrazines. Nickel peroxide has been used to oxidize diphenylamine to tetraphenylhydrazine in moderate yield, and other secondary arylamines also give... 

Historical note. A description of a procedure for the preparation of hydrazine sulfate is presented here as a commentary on changing times and on the fortitude of chemists who, in 1921, founded Organic Syntheses. The senior submitter of the procedure was Roger Adams, who had edited Volume 1 his co-worker was B. K. Brown. The senior checker, James B. Conant, was editor of Volume 2 of 1922 in which the procedure was first published his co-worker was W. L, Hanaway. The basic reactions are simple enough oxidation of ammonia with hypochlorite and isolation of the product as the sulfate ... 

With regard to the simple diaziridine synthesis under large-scale conditions from ketone, ammonia, and chlorine, - some patents claim a direct preparation of hydrazine products by reaction of diaziridines with suitable reagents. For example, hydrazine dicarboxylic acid diamide is obtained directly from 3-ethyl-3-methyldiaziridine and urea in acidic so-lution. The reaction conditions, however (some hours at 70°-80°C), point to acid hydrolysis prior to reaction with urea. 

Methods heretofore known for the preparation of hydrazine in anhydrous condition were both tedious and uneconomic. It is the object of the present invention to provide a simple process for obtaining anhydrous hydrazine in high yield. 

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