Organic Syntheses Part 6

[2] Ann. chim. phys. (3) 60, 18 (1860).

[3] D. R. P. 180,668; Frdl. 8, 27 (1907); J. Am. Chem. Soc. 42, 2096 (1920).

[4] D. R. P. 197,309; Frdl. 9, 34 (1908).

[1b] D. R. P. 197,308; Frdl. 9, 33 (1908).

[2b] D. R. P. Anm. 23,510; 16,579; Frdl. 9, 36 (1908).

[3b] D. R. P. 201,230; Frdl. 9, 35 (1908).

X

HYDRAZINE SULFATE

2 NH3 + NaOCl--> NH2NH2 + H2O + NaCl

Prepared by ROGER ADAMS and B. K. BROWN. Checked by J. B. CONANT and W. L. HANAWAY.

1. Procedure

A NORMAL solution of sodium hypochlorite is prepared as follows: in a 5-l. round-bottom flask are placed 1800 g. of sodium hydroxide solution (300 g. of sodium hydroxide to 1500 g.

of water) and 1500 g. of ice. Chlorine gas is then pa.s.sed into the solution until it has gained in weight approximately 213 g.

During this addition, the solution must be kept thoroughly cooled with ice, in order that chlorates will not be formed.

After all the chlorine has been pa.s.sed in, it is necessary to be certain that the mixture is slightly alkaline, since any excess of free chlorine in the solution prevents the formation of hydrazine.

In a 14-inch evaporating dish are placed 1500 cc.

of c. p. ammonia water (sp. gr. 0.90), 900 cc. of distilled water, 375 cc. of 10 per cent gelatine solution, and 1200 cc.

of the normal sodium hypochlorite solution prepared as above.

This mixture is heated as rapidly as possible and boiled down until one-third of the original volume is left. This solution is then cooled thoroughly with ice and filtered with suction, first through two layers of toweling and then through one thickness of ordinary filter paper over cloth, in order to remove finely divided solid impurities. The solution is then placed in a precipitating jar, and cooled down thoroughly (0'0) with ice and salt; 10 cc. of concentrated sulfuric acid for each 100 cc.

of solution are gradually added with constant stirring.

A precipitate of hydrazine sulfate (NH2NH2<.>H2SO4) forms.

The mixture is allowed to stand in the cold for a few hours in order to complete the precipitation, and is then filtered by suction in the usual way and washed with cold alcohol. The yield varies from 53 g.

to 58 g. per 1500 cc. of ammonia water (34-37 per cent of the theoretical amount). The product is perfectly white and crystalline, and satisfactory for almost any purpose. If an absolutely pure product is desired, it must be recrystallized from water.

For every 21 g. of crude product, 100 g. of boiling water are used.

If the crude hydrazine is brown, it is advisable to use a little bone-black. After the mixture has been filtered and cooled to 0'0, 19 g.

of pure white crystals are obtained.

2. Notes

In the preparation of the sodium hypochlorite solution it is quite necessary that the mixture be kept cold and be alkaline to red litmus paper at the end of the reaction, if good yields of hydrazine are to be obtained.

Since iron is an anti-catalyzer, it is necesssary{sic} to use distilled water throughout the process.

As a viscolizer, a substance such as starch, glycerol, glue or gelatine may be used; the last, however, gives by far the most satisfactory results.

In order to obtain a pure white hydrazine sulfate as the first precipitate, it is necessary to cool the hydrazine solution thoroughly and filter it twice before the sulfuric acid is added.

Moreover, the sulfuric acid must be added slowly and with stirring.

If these conditions are not followed, material containing brown particles results.

The mother liquor obtained from the crystallized hydrazine sulfate contains a small amount of hydrazine. If 200 g.

of copper sulfate are dissolved in water and added to 10 l.

of the filtrates from the above processes, a light-blue crystalline precipitate of the double salt of copper sulfate and hydrazine sulfate will be formed after ten hours. This salt, when suspended in ten times its weight of distilled water and treated with hydrogen sulfide, decomposes into copper sulfide and hydrazine sulfate.

After the copper salt has been filtered off, the solution is concentrated until the hydrazine sulfate crystallizes.

The yield of product is small, so that it is hardly advisable to undertake this recovery in the laboratory.

It is possible for one man, simultaneously evaporating six dishes of the hydrazine mixture, to turn out from 20 to 25 runs in nine hours.

The time for the evaporation of a solution, such as is mentioned in the experimental part, with a four-flame Bunsen burner, is two to three hours; if the evaporation is carried out more slowly than this, the yield of product is distinctly diminished.

3. Other Methods of Preparation

Hydrazine salts have been prepared by the action of hypochlorites on ammonia[1] or urea;[2] by the hydrolysis of salts of sulfohydrazimethylene disulfonic acid;[3] by the hydrolysis of triazoacetic acid;[4] by the reduction of diazoacetic ester;[5] by the reduction of nitroguanidine followed by hydrolysis;[6] by the reduction of the nitroso derivatives of hexamethylene tetramine;[7] by the reduction of nitrates or nitrites with zinc in neutral solution;[8] by the action of sodium bisulfite on hyponitrous acid followed by reduction;[1b] by the reduction of K2SO3N2O2;[2b] by the action of ammonia on dichlorourea;[3b]

by the reduction of nitrosoparaldimin;[4b] by the action of copper sulfate on ammonia at high temperatures;[5b] by the reduction of methylene diisonitrosoamine;[6b] by the hydrolysis of the addition product of diazoacetic ester and fumaric or cinnamic esters.[7b]

[1] D. R. P. 192,783; Chem. Zentr. 1908 (I), 427; Chem. Ztg. 31, 926 (1907); D. R. P. 198,307; Chem. Zentr. 1908 (I), 1957; Eng. Pat.

22,957; C. A. 2, 1999 (1908); U. S. Pat. 910,858; C. A. 3, 1065 (1909); French Pat. 382,357; C. A. 3, 2358 (1909); Ber.

40, 4588 (1907); Laboratory Manual of Inorganic Preparations, by A. B. Lamb, Harvard University, Cambridge, Ma.s.s.

[2] J. Russ. Phys. Chem. Soc. 37, 1 (1905); Chem. Zentr. 1905 (I) 1227; D. R. P. 164,755; Frdl. 8, 53 (1905); French Pat. 329,430; J. Soc. Chem. Ind. 22, 1063 (1903); Chem. Zentr. 1905 (I) 1227.

[3] D. R. P. 79,885; Frdl. 4, 26 (1895); Ber. 28, 2381 (1895).

[4] Ber. 20, 1632 (1887); Chem. News 55, 288 (1887); D. R. P. 47,600; Frdl. 2, 554 (1889); J. prakt. Chem. (2) 39, 27 (1889).

[5] Ber. 27, 775 (1894); 28, 1848 (1895); D. R. P. 58,751; Frdl. 3, 16 (1891); D. R. P. 87,131; Frdl. 4, 28 (1896).

[6] Ann. 270, 31 (1892); D. R. P. 59,241; Frdl. 3, 16 (1891); Eng. Pat. 6,786; J. Soc. Chem. Ind. 11, 370 (1892).

[7] D. R. P. 80,466; Frdl. 4, 27 (1895); Ann. 288, 232 (1895).

[8] Eng. Pat. 11, 216; J. Soc. Chem. Ind. 14, 595 (1895). [1b] Ber.

33, 2115 (1900); Ann. 288, 301 (1895).

[2b] Ber. 27, 3498 (1894).

[3b] J. Chem. Soc. 95, 235 (1909); Chem. News 98, 166 (1908).

[4b] Ber. 23, 752 (1890).

[5b] Chem. News 66, 223 (1892).

[6b] Ber. 27, 3292 (1894);

[7b] Ber. 21, 2637 (1888).