April, 1923
I X D USTRIAL AND EiVGINEERIil-G CHEMISTRY
proportional to the molecular concentration of the phenolt h a t is, the factor for these various phenols can be calculated from its molecular weight. In this case any of these monohydric phenols could have been used as a standard. @-Naphthol, because of the ease with which it can be obtained pure and the fact that it is a solid a t ordinary temperatures and can belweighed direct, is the most convenient one. Only monohydric phenols were investigated to any extent in this work. An attempt was made to determine resorcinol by this method, n i t h @-naphtholas a standard, but the color obtained by the
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resorcinol used was of so different a shade that an accurate reading was impossible. CONCLUSION The determination of a number of monohydric phenols by the reagent of Folin and Denis can be accomplished with a fair degree of accuracy without the use of an empirical factor by following a uniform procedure. P-Naphthol, isoamyl phenol, and probably some of the other solid monohydric phenols are good standards for color comparison of phenols.
T h e Preparation and Separation of Ortho- and ParaChloroani li n eslr2 By H. C. Bashioum and P. 0.'Powers UKIVERSITY O F PITTSBURGH. PITTSBCRG€I. P A
HLOROBENZE N E is a much weaker base, and The purpose of. this investigation was a study of the preparafion was nitrated, and its sulfate is sufficiently of 0- and p-chloroanilines, especially ihe o-chloroaniline. It seemed after a part of the hydrolyzed to allow it to be possible that o-chloroaniline might be used in the preparation of a distilled from the solution p-nitrochlorobenzene had large number of azo dyes, replacing aniline, the toluidines, and been separated, the remainwith steam. xylidenes-naturally, with some change in shade. A f e w such ing mixture of 0- and p-niThe isomers can also be dyes have been prepared, mostly monazo dyes, and a f e w triphenyltrochlorobenzenes was reprepared and separated by methane and other types of dyes.3 There seems to be no reason why duced. The original mixforming the sulfates in a the chloroanilines cannot be prepared easily on a large scale and at a ture of nitro compounds reasonable price. warm solution and cooling. is not easily separated. p-Chloroaniline sulfate is Therefore, an attempt was nearly insoluble in cold made t o obtain the pure o-chloroaniline after reduction; also water, while the sulfate of o-chloroaniline is much more t o find the best and most economical method for preparing soluble. 0-Chloroaniline may be recovered by neutralizing this compound. the acid solution with an alkali. Other methods are known-e. g., the fractional crystallizaPREPARATION OF THE CHLOROANILISES tion of the picrates and acetyl derivatives-but these methods A mixed acid, consisting of concentrated sulfuric acid and were not investigated. a slight excess over the theoretical amount of nitric acid, was In order to eIiminate the two distillations or the necesused t o nitrate the chlorobenzene. Under the conditions sity of crystallization, direct steam distillation from the used the nitration was not always complete, and this led to completely reduced mixture was tried. When sulfuric acid difficulties in the later steps. The mixture of 0- and p-nitro- was used in the reduction the method was not successful, chlorobenzenes was separated from the spent acid and allowed since but little oil came over.with the steam. Using someto cool to below 20" C. A large part of the para isomer what less than an equivalent of hydrochloric acid in the rewas thus separated in a very pure state, leaving an oil con- duction and steam distilling a t its completion, a quite pure taining about equal amounts of the isomeric nitro compounds. o-chloroaniline was obtained which could be further purified The reduction was found to proceed smoothly if chloro- by redistillation. benzene was not present in the oil. Iron filings and hydroThe presence of uiiiiitrated chlorobenzene led to difficulties chloric acid was found to be the most economical reducing in the reduction, since it took much longer to complete the agent. Much less than the tbeoretical amount of hydro- process and also prevented separation by steam distillation. chloric acid was used. Sulfuric acid was tried, but with this In this case fractional precipitation of the sulfates was used. acid more than a full equivalent, also more time, was required. p-Chloroaniline was recovered by steam distillation after The separation of the chloroanilines may be accomplished neutralization of the solution from which the o-chloroaniline in several ways. Beilstein and Kurbatow' suggest several had been distilled. It may also be prepared by complete redifferent methods. The simplest is steam distillation from duction, using iron and hydrochloric acid, of the p-nitroa neutral solution, which gives only a partial separation, and chlorobenzene separated from the nitration mixture. After the o-chloroaniline which distils over first is redistilled from a neutralization a very pure p-chloroaniline is obtained. solution to which an equivalent of sulfuric acid has been NITRATIONOF CHLOROBESZEKE added. p-Chloroaniline is a stronger base and cannot be distilled out of such a solution with steam, o-Chloroaniline For the nitration 1000 g. of chlorobenzene were used. 1 Presented beIore the Division of Dye Chemistry a t the 64th Meeting A mixed acid consisting of 1290 g. of 94 per cent sulfuric of the American Chemical Society, Pittsburgh, Pa., September 4 to 8, 1922. acid and 900 g. of 70 per cent nitric acid was prepared and 2 Submitted by P. 0 . Powers in partial fulfilment of the requrement run slowly, with constant stirring, into the chlorobenzene. €or the degree of Master of Science a t the University of Pittsburgh. During the addition of the first half of the acid the tempera3 Bet'., 41 (1914), 1161; Monutsh., 34 (1913), 193; J . Chcm. SOC. ( L o n d o n ) , 91 (l9lO),2388; D R. P 112,176 (1899);126,607(1901); 162,636 ture was kept a t about 2.5" C.; during the addition of the (1904): 202,016 (1908);204,848 (1908):233,367 (1911): 241,853 (1911): second half of the acid the temperature was allowed to rise, 241,910 (1911); 242,051 (1911); 247,411 (1912); 264,942 (1913); 286,237 and finally the mixture was heated on the water bath for (1915). several hours. 4 A n i t , 176 (1875),27.
C
INDUSTRIAL A N D ENGINEERING CHEiWISTRY
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NITRATIONS p-Nitrochlorobenzene Mononitrochlorobenzene Yield Per cent of Per cent of Per cent G. Total G. Total of Theory 260 34 496 66 72 1000 675 48 686 51 97 1000 478 38 783 62 90 REDUCTIONS MononiSteam trochloroDistil- Yield as benzene Time late o-ChloroNo. G. Reducing Agent Hrs. G.u aniline Reduction 2 65 Tin and HCI 5 23 48 Complete IncomIron and HzSO4 1; ;1 plete Complete Iron and HC1 ;.5 Chlorobenzene G. 7 50
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5 I n 2, 3, and 7 the steam distillation was made from neutral solution and p-chloroaniline is included. In No?. 8 and 9 only o-chloroanilinc was in the steam distillate,
The mixture of nitro compounds, a yellow oil consisting of about 70 per cent p- and 30 per cent o-nitrochlorobenzenes,6 was cooled to or below 20' C., when the para compound, equal to about 50 per cent of the total mixture, crystallized out. The crystals and oil were separated by centrifugation, and both washed with water and finally with dilute solution of sodium carbonate until free of mineral acid. The oil contained approximately 50 per cent p- and 50 per cent o-nitrochlorobenzene.
REDUCTION OF THE NITROCOMPOUNDS The spent acid from the nitration process was first used with iron to effect the reduction. Better results were obtained with increasing dilution of the acid. Iron and hydrochloric acid were also tried with much better results, especially if chlorobenzene was absent. Much less time was required than with sulfuric acid. Tin and hydrochloric acid were successfully used, but, since a large excess of hydrochloric acid is used, this must be neutralized before steam distillation and another step taken to separate the isomers. Fractional precipitation of the sulfates is satisfactory for this purpose. The method finally adopted as giving the best results was to add 15 per cent of the weight of the nitro compounds of 6
Proc. Royal Acad. Sci. Amsteudam, 1 (19041, 266.
Vol. 15, No. 4
hydrochloric acid (22' Be.) and the same amount of water to the nitro compounds in a flask and bring to a boil under a reflux condenser. Then a weight of iron filings equal t o the weight of nitro compounds was added in small portions while keeping the mixture a t a boiling temperature. Six hours were found to be sufficient to complete the reduction by this method in the absence of chlorobenzene. (The chlorobenzene may be removed from the mixture of mononitrochlorobenzenes by distillation up to 150" C.) If it were present the reduction might not be complete a t the end of 20 hrs. The odor of the nitrochlorobenzenes disappears a t the end of the reduction. If the color of the steam distillate is red, the reduction is not complete; if colorless, the reduction is complete. SBPARATION OF 0- AND p-CHLOROANILINES Distillation with steam from the completed reduction mixture was found to give a satisfactory separation. When the reduction was finished, the o-chloroaniline was distilled off in a fast current of steam. The p-chloroaniline, being a stronger base, is held back by the presence of hydrochloric acid used in the reduction, and may be recovered by neutralizing with caustic soda or lime and continuing the steam distillation. The o-chloroaniline comes over as a clear, colorless oil, 05 per cent boiling within two degrees of the boiling point of o-chloroaniline. When the reduction could not be completed, the acid was neutralized, and then the chloroanilines and unreduced nitrochlorobenzenes were distilled over with steam. The steam distillate was acidified with sulfuric acid to Congo red and brought to aboil. The unreduced nitro compound was separated while hot, and on cooling the p-chloroaniline sulfate separated out. o-Chloroaniline as an oil was recovered from the filtrate by neutralizing with sodium hydroxide. ~CHLOROANILINE p-Chloroaniline can be made from the separated p-nitrochlorobenzene by reducing, as outlined above, with iron and hydrochloric acid, neutralizing the acid, and steam-distilling. A very good grade of p-chloroaniline is obtained in this way.
Chemical Equipment Companies Offer Coijperation The Chemical Equipment Association, comprising manufacturers of the diversified equipment used in the twenty or thirty chemically controlled American industries, which recently began a national work for the advancement both of chemicalequipment interests and those of the industries which its members supply, has now begun some very important industrial work in support of these purposes, according to announcement just made by its board of directors. The announcement is accompanied by an appeal for cooperation in an informational way by the associations in each of the great industries which manufacturers of chemical equipment supply. The association's committee on standardization, of which E. H. Froman, of the Fuller Lehigh Co., i s chairman, is prepared to cooperate with the users of chemical equipment in any of the American industries in working toward the standardization of trade phrases and in the collection of information leading to simplification and standardization in designing and constructing chemical equipment. The committee on business extension, J. W. Spotten, of the United Lead Co., chairman, in addition to present cooperatlon with the United States Department of Commerce and with other government departments and agencies in activities leading to the more profitable employment by the country's industries of modern chemical equipment, is prepared to collect information on comparative uses of given types of equipment. According to the Chemical Equipment Association, i t is believed that this activity can result in an incalculable benefit to industry as a whole, inasmuch as through it various methods and processes used in connection with chemical equipment in one manufacturing industry but unknown in other industries may be made known elsewhere, and with minor adaptations required, profitably adopted in such other industries.
Another committee, that on ethics, E. C. Alford, Elizabeth, N. J., chairman, is making a survey of commercial and engineering practice among chemical-equipment companies, and also concerning such companies in their relationship with the great American industries purchasing chemical equipment. This committee in due course will recommend a declaration of ethical practice t o govern the activities of chemical-equipment manufacturers, not only in their own interests but in the interest of increased business with and improved protection to the users of chemical equipment. The association's statistical committee, R. Gordon Walker, of the Oliver Continuous Filter Co., chairman, is inaugurating, in connection with various statistical agencies throughout the country and government departments, a compilation of the vital statistics of employment of equipment in the great range of industries using chemical and processing apparatus. The association believes that the collection of these statistics will enable the more economical preparation of equipment for users and its more economical purchase by them. Other committees, on industrial relations, E. J. Fowler, of the Pacific Foundry Co., chairman; and on membership, T.C. Oliver, Chemical Construction Co., chairman; on legislation and publicity, Irving Fellner, Chemical & Metallurgical Engineering, chairman, have also been appointed. The Chemical Equipment Association welcomes and requests the cooperation of individuals, companies, or associations in a position to assist in the work of its important committees. These may communicate with the association a t its executive office, 1328 Broadway, h'ew York City.
