Chapter 3

The most convenient hydrogen chloride generator is that described by Sweeney.[1] Concentrated hydrochloric acid is introduced into concentrated sulfuric acid, by means of a dropping funnel and a _capillary tube leading to the bottom of the sulfuric acid container_. It is convenient to use a 3-l. bottle for this container and a 1-l. funnel to contain the hydrochloric acid. The gas is dried by passing through a wash-bottle containing concentrated sulfuric acid. An empty catch-flask should be connected between the generator and the absorption flask in case any glycerol tends to suck back at the start of the reaction. About 6 kg. of concentrated hydrochloric acid and 10 kg. of concentrated sulfuric acid are required in one run. The generating flask will have to be recharged every six hours; it should be half filled with sulfuric acid. Aside from this, the apparatus needs no attention. The oil bath can be conveniently heated on an electric hot plate.

The dichlorohydrin boiling over a 7'0 range is sufficiently pure for most purposes. It contains very little, if any, isomeric dichlorohydrin, since on oxidation it gives dichloroacetone in good yields.

3. Other Methods of Preparation

The following methods of preparing dichlorohydrin are described in the literature: the action of gaseous hydrogen chloride on glycerol;[1b] the action of gaseous hydrogen chloride on glycerol mixed with an equal volume of acetic acid;[2] the action of hydrogen chloride gas on glycerol containing 1-2 per cent of some organic acid, as acetic, as a catalyst;[3] the action of aqueous solution of hydrochloric acid on glycerol containing acetic acid as a catalyst;[4] the action of sulfur monochloride on glycerol.[5]

The previous work, described in the literature, indicated that the best yields were obtained by the treatment of glycerol containing 1-2 per cent of acetic acid as a catalyst by gaseous hydrogen chloride. Therefore this method was employed.

[1a] J. Am. Chem. Soc. 39, 2187 (1917)

[1b] Ann. 88, 311 (1853); Ann. chim. phys. (3) 41, 297 (1854); (6), 22, 437 (1891); Bull. soc. chim. (2), 48, 237 (1887); Z. physik. Chem. 92, 717 (1918); 93, 59 (1919); 94, 691 (1920); D. R P. 263,106; 272,337; Frdl. 11, 33 (1912).

[2] Ann. Spl. 1, 2I8 (1861); Ann. chim. phys. (3) 60, 18 (1860).

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

[4] D. R. P. 197,309; Frdl. 9, 33 (1903).

[5] Ann. 122, 73 (1862); 168, 43 (1873); Ber. 5, 354 (1872); Ann. chim. phys. (6) 22, 437 (1891).

IX

GLYCEROL a-MONOCHLOROHYDRIN

C3H5(OH)3 + HCl--> CH2ClCHOHCH2OH + H2O

Prepared by J. B. CONANT and O. R. QUAYLE. Checked by O. KAMM and A. O. MATTHEWS.

1. Procedure

FIVE HUNDRED grams of glycerol (90 per cent) and 10 g. of glacial acetic acid are mixed in a weighed 1-l. flask, which is placed in an oil bath heated to 105-110'0. A rapid stream of dry hydrogen chloride is introduced into the mixture. The flask is removed from the bath from time to time and reweighed. At the end of about four hours the flask will have gained 190 g. in weight. The reaction is then complete.

The product is distilled under diminished pressure. Below 114'0/14 mm., 220-250 g. distil; this portion is mostly water. The monochlorohydrin is collected between 114-120'0/14 mm.; it weighs 360 g., which is 66 per cent of the theoretical amount. About 20 g. more may be obtained by neutralizing the first fraction and separating the aqueous layer.

2. Notes

The same apparatus is employed as in the preparation of dichlorohydrin (preparation VIII, p. 29).

The portion boiling 120-130'0/14 mm. only amounts to 15-30 g., showing that very little of the b-compound is formed. This is further shown by the fact that the dichlorohydrin formed by continued action of hydrogen chloride under the same conditions contains very little, if any, a, b dichloride.

Two kilograms of concentrated sulfuric acid and 750 g. of concentrated hydrochloric acid are sufficient to produce the necessary amount of hydrogen chloride.

A light straw-colored final product is obtained in some cases.

An alternative procedure which is slower and gives slightly lower yields, but does not require a hydrogen chloride generator, is as follows:

Three hundred grams of glycerol, 600 cc. of hydrochloric acid (sp. gr. 1.19) and 15 g. of glacial acetic acid are heated under a reflux condenser for ten hours, in a 2-l. flask. The boiling should be very gentle in the early stage of the reaction, as considerable hydrochloric acid vapor is evolved. As the reaction progresses, and the evolution of acid vapors diminishes, the mixture is more strongly heated.

The reaction products are distilled under ordinary pressure until the temperature of the liquid has reached 140'0 (thermometer bulb immersed in the liquid). The residual products are distilled under diminished pressure, and the following fractions obtained. (1) Up to 115'0/11 mm.; (2) 115-117'0/ 11 mm.; (3) 117-170'0/11 mm. (1) is mostly aqueous hydrochloric acid; (2) is the monochlorohydrin; and (3) is glycerol. The second portion is redistilled and the portion boiling at 115-118'0/11 mm. or 133-136'0/20 mm. is collected. The yield is 190-205 g., 53-57 per cent of the theoretical amount.

3. Other Methods of Preparation

The following methods of preparing monochlorohydrin are described in the literature: action on glycerol of gaseous hydrogen chloride;[1] action of gaseous hydrogen chloride on glycerol mixed with an equal volume of acetic acid;[2] action of aqueous hydrochloric acid on glycerol[3] alone or with an organic acid (1-2 per cent), such as acetic, as a catalyst;[4] gaseous hydrogen chloride with an organic acid, as acetic, as a catalyst;[1b] gaseous hydrogen chloride with the ester of an organic or inorganic acid as a catalyst;[2b] the action of sulfur monochloride on glycerol.[3b]

[1] Ann. 88, 311 (1853); Ann. chim. phys. (3) 41, 297 (1834); V. R. P. 254,709; 269,657; Frdl. 11, 31 (1912).

[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 passed 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 passed 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, Mass.

[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).

XI

MESITYLENE

3 CH3COCH3 + (H2SO4)--> C6H3(CH3)3 +3H2O

Prepared by ROGER ADAMS and R. W. HUFFERD. Checked by H. T. CLARKE and W. W. HARTMAN.

1. Procedure

IN a 12-l. round-bottom flask, arranged so that the contents can be mechanically stirred, are placed 4600 g. (5750 cc.) of technical acetone. The flask is then well cooled with an ice-and-salt mixture, until the temperature of the acetone is between 0'0 and 5'0. Stirring is started, and 4160 cc. of commercial concentrated sulfuric acid is run in at such a rate that the temperature of the mixture never rises above about 10'0. This addition is accomplished in about five to ten hours. The stirring is continued for three to four hours longer, while the flask still remains immersed in the original freezing mixture to which no further amount of ice is added. The mixture is then allowed to stand at room temperature for eighteen to twenty-four hours.

A 5-l. round-bottom flask is fitted with a rubber stopper or a cork stopper coated with pitch, carrying two glass tubes, one of which (for the entrance of steam) reaches to the bottom of the flask, while the other extends into the open end of a condenser set for downward distillation. The stopper should be wired into the flask. The glass delivery tube into the condenser should not be less than a 12-mm. bore, and the condenser should consist of two 120-cm. water-cooled condensers attached end to end. To the end of the condensing system, an adapter is attached, the small end of which is at least 8 mm. in bore and is fitted tightly into a stopper in a 2-l. suction flask. To the side-arm of the suction flask is attached a tube leading to an exhaust fan, in order to carry away the gases which are evolved during the subsequent distillation. In the 5-l. flask are placed about 2 l. of the sulfuric acid-acetone reaction mixture, and the flask is then heated with a free flame and shaken occasionally. A reaction starts at the end of about fifteen or twenty minutes, as shown by the evolution of gas (chiefly sulfur dioxide), and is allowed to run for about three minutes. At the end of this time, a current of steam is passed in and continued for about three minutes. During this period a large proportion of the mesitylene distils and should be kept separate from the subsequent distillate. The steam distillation is continued at such a rate that about 800 cc. distils in twenty-five to thirty minutes and is collected as a second distillate. At the end of this time, the distillation is stopped, the water poured off from the distilling flask and the tarry material emptied out while hot into waste jars. The total amount of original reaction mixture requires five distillations similar to the one just described. The first distillates from each of the five distillations are mixed, and the layer of mesitylene is separated from the water. This is shaken with sodium hydroxide solution until no more odor of sulfur dioxide is noticeable, then washed twice with water and distilled. The first portion of the distillate consists of a small amount of water and mesitylene and is added to the combined second distillates. The fraction which distils up to 210'0 is saved. The second distillates are combined, washed in the same way as the first and then distilled; the fraction which distils up to 210'0 is combined with the corresponding fraction from the first distillates.

These combined fractions (which boil up to 210'0) and 15 g. of sodium are placed in a 2-l. distilling flask, the side-arm of which is closed with a rubber tube and pinchcock and which is fitted with a reflux condenser. The mixture is heated just below the boiling point for about three hours, during which time the impurities are attacked by the molten sodium, and a gelatinous, reddish mass forms. The reflux condenser is now removed and one set for downward distillation is attached to the side-arm. The mixture is distilled and about two-thirds of the liquid removed in this way. The residue is cooled, the liquid poured off from solid material and distilled up to 210'0.

The distillates from the sodium treatment are now fractionated with a good column (at least 30 cm. long), and the portion which boils at 163-167'0 is collected. The yield of this fraction varies in different runs from 430 to 470 g. (13-15 per cent of the theoretical amount), but very often will be as high as 500 g., and has reached, in certain experiments, 600 g.

An alternative method for the purification of the crude material has been employed by Clarke and Hartman, and yields a slightly higher-grade product than the sodium method. It is as follows:

The combined distillates are treated with an equal volume of concentrated sulfuric acid and the solution warmed on a water bath for an hour, under a reflux condenser, with occasional shaking or, better, with mechanical stirring. Upon cooling, mesitylene sulfonic acid crystallizes and the unsulfonated material remains as an oil on the surface. The mixture is filtered through flannel or a "filtrose" plate, and the crystals are washed with 60-70 per cent sulfuric acid. The oily layer is again warmed with sulfuric acid, as before. The acid and oily filtrates from the two sulfuric acid treatments are steam distilled, and the distillate combined with the next batch of material. The crystals are mixed with 2 l. of 15 per cent hydrochloric acid and heated under a reflux condenser for two to three hours. The reaction mixture is now steam distilled, the mesitylene separated, dried over calcium chloride and fractionated; the portion which boils at 163-167'0 is collected.

2. Notes

The cooling of the reaction flask must be very efficient, a 10-15 cm. blanket of a thorough mixture of ice and salt being used. If this precaution is not employed, the time for the addition of the sulfuric acid is greatly increased, provided the temperature of the reaction mixture is still kept within the limits mentioned.

If a cork is used for the steam distillation of the reaction mixture of acetone and sulfuric acid, it should be coated well with pitch and wired into the flask. This is necessary because the vapors of the reaction mixture attack an ordinary cork very badly, and soften it so much that it is necessary to rewire it to prevent it from slipping out. A rubber stopper is satisfactory and may be used in several runs.

The evolution of gas is so vigorous that it is not possible to distil more than 2 l. of the original reaction mixture at one time in the apparatus described. The connections on the apparatus, in which the mesitylene is obtained from the crude reaction mixture, should be tight, since the fumes evolved during the heating are very irritating.

The product which distils during the initial heating and the three minutes of steam distillation is mainly satisfactory material; the rest of the steam distillation yields only a small amount of pure product. The two portions of the distillate are, therefore, kept separate, since the second distillate always contains a considerable amount of high-boiling product which tends to cause emulsification of the alkali in the purification. No recovery of acetone is made.

The mechanism of the reaction is undoubtedly as follows: when the sulfuric acid and acetone are in contact for long periods of time, several molecules of the acetone condense to form aldol condensation products. These do not break down into mesitylene until the temperature is raised in the second part of the experiment.

While the original reaction mixture is standing, the temperature gradually rises to 40'0 or 50'0 in the course of six to ten hours, and then gradually cools off again. It is probable that at the end of this time (when the flask has cooled again) the reaction mixture could be distilled with nearly as good a yield as is obtained after standing eighteen to twenty-four hours.

The wide variation in yields which are mentioned in the experimental part is probably due to a slight change in the grade of the chemicals which are used in this preparation. 3. Other Methods of Preparation

The cheapest and most convenient method by which mesitylene may be prepared is by the action of a dehydrating agent upon acetone; the agent most commonly used is sulfuric acid.[1] It has been shown also that phosphoric acid will convert acetone to mesitylene.[2] A number of other methods have also been used for the preparation of mesitylene: the action of sulfuric acid on methyl acetylene;[3] the action of sulfuric acid on mesityl oxide and phorone;[4] the action of aluminium{sic(british)} chloride on methyl chloride and benzene;[5] the action of mineral acids upon mesitoyl or benzoyl mesitylene;[6] the action of phosphoric acid upon diaceto-mesitylene;[7] the treatment of methylene-3-dimethyl-1, 5-cyclo-hexene-1 with bromine and then with alcoholic potash.[8]

[1] Ann. 141, 131 (1867); 147, 43 (1868); 278, 210 (1893); Bud. soc. chim. (2) 40, 267 (1883); J. prakt. Chem. (1) 15, 129 (1838); Am. Chem. J. 15, 256 (1893); 20, 807 (1898).

[2] J Chem. Soc. 99, 1251 (1911).

[3] Ber. 8, 17 (1875).

[4] Ber. 7, 1169 (1874); 10, 858 (1877).

[5] Ber. 12, 329 (1879); Ann. chim. phys. (6) 1, 461 (1884).

[6] Ber. 32, 1910 (1899).

[7] Ber. 32, 1563 (1899).

[8] Ber. 43, 3093 (1910).

XII

METHYL RED

(_o_)HO2CC6H>4s>NH2 + HNO2 + HCl-->(_ o_)HO2CC6H4N2Cl + H2O (_o_) HO2CC6H4N2Cl + C6H5N(CH3)2-->(_ o_)HO2CC6H4N = NC6H4N(CH3)2 + HCl

Prepared by H. T. CLARKE and W. R. KIRNER. Checked by ROGER ADAMS and J. B. DAVIS.

1. Procedure