Summary
The effect of Tanations in the concentration of the dye in solution is studied in the case of methylene blue. It is shown that variations within the customary limits used in spectrophotonietric practice, 2 to 10 parts of dye per million
of solvent, have a very appreciable effect on the values of the extinction coefficient and that such effects must be considered in quantitative spectrophotometric work. It seems well from these results to consider alcohol, which is devoid of such effects, as a solvent for quantitative work of this nature.
New Dye Intermediates'.? 2,4-Diaminophenyl Oxide, 2-Nitro-4-Aminophenyl Oxide, and 2,4-Diaminophenyl Sulfide By Marston T . Bogert and Ralph L. Evans COLUMBIA UNIVERSITY, NEWYORK. N.Y.
T SEEUS strange, in view of the availability and rela- deeper penetration. In the second place, the reaction tive cheapness of 2,4-dinitrochlorobenzene and phenol, between the phenolate and the dinitrochlorobenzene is that the 2,4-diamino- and -nitroaminophenyl ethers, strongly exothermic, and if not conducted properly, or in which are phenoxy derivatives of the important dye inter- the presence of a suitable solvent-for example, excess of result in fire or explosion. The foregoing mediates m-phenylenediamine and m-nitroaniline, find so phenol-may little mention in chemical literature. The research lab- statements apply equally to the corresponding thio ether. Within recent years Cook5 has been the leading investioratories connected with various great dye plants, both here and in Europe, undoubtedly have investigated in a gator of the nitroaryl ethers in this country. I n the course preliminary way the possibilities of these obviously ac- of his work on 2,4-dinitrophenyl ether, he reported that "attempts to reduce the cessible intermediater, and the lack of any resultant 1, ,I nitro groups with tin and hydrochloric acid were unpublications or patents on 2,4-Dinitrophenyl oxide has been reduced successfully successful. The base detheir part leads to the both to the 2-nitro-4-aminophenyl oxide and to the composed immediately upon that from such intermedidiamine. 2,4-Dinitro- and diaminophenyl sulfide have exposure to the air;" and either n' dyes Obbeen prepared from 2,4-dinitrochlorobenzeneand their this statement may have detained cheaper O r b e t t e r properties studied. From these derivatives of rnthan Others On the terred others from undernitroaniline and rn-phenylenediamine azo dyes have Or that the difficultaking the preparation of been produced by the usual methods. t i e s e n c o u n t e r e d in the the diamine. The writers large-scale manufactlire of ' 1 '1 have been more fortunate in t h e dinitro ether distheir experiments, since they couraged further work. For the benefit of those who do not have succeeded in reducing the dinitro to the diamino derivahave access to the research records of these dye factories, as a tive and have found that the latter when pure is crystalline, contribution to the literature of the subject, and because we be- practically colorless, and quite stable in the air. lieve that there exists the possibility of discovering useful prodI n addition to the free base, its hydrochloride and diacetyl ucts in this field, the present paper is offered as a first report. derivative were prepared. By the usual diazo reactions, Various nitro- and aminophenyl ethers have been de- various azo dyes were produced from this phenoxy-mscribed hitherto, and the 2,4-dinitro derivative has been known phenylenediamine. for many year^,^^^ the reaction by which it is produced By operating under these conditions the dinitro ether being a simple one. was reduced to the 2-nitro-4-aminophenyl ether. This phenoxy-m-nitroaniline diazotized and coupled easily to form azo dyes of the ordinary type. Its diazonium salt proved to be remarkably stable. By substituting potassium thiophenolate for the phenolate in the reaction with dinitrochlorobenzene, the corresponding There are two things to be guarded against, however, dinitro- and diaminophenyl sulfide were obtained. ,4s might in the preparation of this dinitro ether. I n the first place, have been expected, the azo dyes from the latter yield darker the dinitrochlorobenzene is a powerful skin irritant, and if shades than the corresponding oxygen compounds. The dyes produced from these new intermediates will any gets on exposed portions of the body it should be washed off immediately with strong sodium carbonate solution. be discussed more fully in a subsequent communication. The dinitro ether itself has but little of this action and is 2,4-Dinitrophenyl Oxide likely to affect very sensitive areas only, except in those I n a large mortar 400 grams of dinitrochlorobenzene cases where its solution in organic liquids may give it a were mixed gradually with 300 grams of dry pulverized 1 Presented before the Division of Dye Chemistry at the 69th Meeting potassium phenolate by first grinding small amounts toof the American Chemical Society, Baltimore, Md., April 6 to 10, 1925.
I
Received November 19, 1925. Contribution No. 500 from the Chemical Laboratories of Columbia University, 8 Maikopar, B e y . , 6, 564 (1873). Willgerodt, Zbrd , 12, 762 (1879).
'
' Cook, el
al., ( a ) A m . Chcm. J . , 24, 525 (1900); (b) 28, 486 ( d ) 24, 1200 (1902); ( e ) 26, 60 v) 26, 302 (1904); (g) 98, 608 (1906); ( h ) A m . Chem. J., SC, 543 (0J . A m . Chem. SOL.,32, 1292 (1910); ci) 83, 254 (1911); (k)S7, IS35 ( I ) Sa, 1534 (1916); (m)Proc. S . Dak. A c a d . Sci., 2 , 21 (1919). (c)
J. A m . Chem. SOL,23, 806 (1901);
(1901); (1903); (1906); (1915);
300
I-VDUSTRIAL S,VD EAVGINEERING CHEXISTRY
gether, keeping the phenolate in excess, and then slowly grinding in additional amounts of the two reactants until all was thoroughly mixed. As previously noted, this reaction is strongly exothermic and must be carried out carefully, or the temperature may rise to the ignition point of the mixture. This is most likely to occur when large amounts of the two components are permitted t o accumulate before being brought into reaction by mixing and grinding. Upon the conclusion of tbe reaction the mixture was left overnight, after which i t was pulverized under water, the water decanted, the residue washed thoroughly with dilute caustic soda, and finally with water again. The insoluble product was decolorized and crystallized from a mixture of 10 parts of acetone and 90 parts of alcohol (94 per cent), giving long pale yellow needles, m. p. 69" to 70" C.; yield, 500 grams. This product is sufficiently pure for reduction t o the nitroamine or diamine. By further crystallization t h e melting point may be raised to 70" C. (cor.), in agreement with the figure reported by Cook. 2-Nitro-4-Aminophenyl Oxide To a vigorously stirred mixture of 100 grams of the finely pulverized dinitro derivative and 250 cc. of alcohol there was added slowly a mixture of 260 grams of crystallized stannous chlopide and 250 cc. of concentrated hydrochloric acid, maintaining the temperature below 60" C. and continuing the stirring for an hour after the addition of the stannous chloride and hydrochloric acid. The mixture was then filtered and the filtrate precipitated by the addition of 250 cc. of ammonium hydroxide solution. The garnetred crystalline precipitate (130 grams) was extracted with boiling alcohol, and as this extract cooled it deposited the nitroamine in beautiful garnet-red prisms or orange-red plates, m. p. 107" to 108" C. (cor.), which melting point was not altered by further crystallization; yield, 32 grams. It dissolved in strong acids and was precipitated again by dilution. Anaiyysis. Calculated for ClzHloOsNa: C, 62.61; H, 4.35 per cent. Found: C, 62.20; H, 4.55 per cent. Attempts to prepare this nitroamine by the use of ammonium or sodium sulfides as reducing agents were unsatisfactory. Occasionally the odor of phenol was noted, indicating at least partial hydrolysis of the ether. Acetyl Derivative A glacial acetic acid solution of the nitroamine containing an excess of acetic anhydride was warmed and left overnight a t laboratory temperature, after which it was precipitated by a large volume of water containing a little ammonia. When this precipitate was crystallized from alcohol, two different sets of crystals were obtained. The one present in larger amount formed beautiful pale yellow needles, m. p. 118" C. (cor), On hydrolysis with concentrated hydrochloric acid and a little alcohol, it gave the nitroamine (m. p. 107" to 108" C., cor.) again, and the odor of ethyl acetate was noted. Analysis. Calculated for C14H120*N~:C, 61.76; H, 4.41 per cent. Found: C, 61.99; H, 4.47 per cent. This product was unchanged when boiled with excess of acetic anhydride and no diacetyl derivative was detected. The other product formed in the initial acetylation of the nitroamine consisted of a few diamond-shaped prisms, m. p. 124" C . (cor.), and on hydrolysis with concentrated hydrochloric acid and a little alcohol likewise yielded ethyl acetate and the original nitroamine. A mixture of approximately equal parts of this compound and of the acetyl derivative, m. p. 118' C. (cor.), melted a t 122" C. Vnfortu-
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nately, not enough material remained for an analysis and it was not encountered in subsequent experiments. Proof of Structure of the Nitroarnine A mixture of 5 grams of the nitroamine, 35 cc. of alcohol, and 3 cc. of concentrated sulfuric acid was treated with a solution of 1.8 grams of sodium nitrite and 5 cc. of water and warmed at 100" C. until a clear solution was obtained. The odor of acetaldehyde was pronounced during this heating. To the clear solution there were added 100 cc. of water, 5 cc. of concentrated sulfuric acid, and 100 cc. of benzene. The mixture was shaken vigorously and the two layers separated hot. The benzene layer was washed with dilute caustic soda, and then with water, the benzene distilled, and the residue subjected to treatment with superheated (150' C.) steam. From this distillate there separated an oil of agreeable odor, which remained liquid at -20" C., dissolved easily in warm concentrated sulfuric acid, and separated again as an oil when the latter solution was diluted. It was easily sulfonated by the action of concentrated sulfuric acid at 100" C. These properties coincide with those of 2-nitrophenyl ether recorded by Haeussermann and Teichmann,e and by Jones and Cook,5' and are totally different from those of the 4-nitro isomer, which melts at 123" C. and has a very low vapor pressure. The original nitroamine, therefore, must have been the 2-nitro-4-amino derivative and not the 2-amino-4-nitro. 4-Phenoxy-3-NitrophenyldiazoniumChloride
Although readily soluble only in high acid concentrations, the nitroamine diazotized smoothly, and addition of acetic acid was of service in increasing its solubility. It combined readily with suitable couplers to form azo dyes; with a-naphthol the dye was a rich fuchsine red, with p-naphthol a brown. The stability of the diazonium salt was shown by the fact that even after its aqueous solution had been boiled for a full minute it still gave the beautiful red dye with a-naphthol. On longer boiling the solution gradually darkened, and with sodium carbonate gave a brown precipitate. Phenoxy Alizarin Yellow GG A solution of 4.2 grams of the nitroamine in 20 cc. of 6 M hydrochloric acid was diazotized at 0" C. with 1.35 grams of sodium nitrite and the solution diluted to 50 cc. with ice water. This solution was mixed with one prepared from 2.5 grams of salicylic acid, 6.25 grams of sodium carbonate, and 40 cc. of water and ice, adding more carbonate and ice during the coupling if necessary, and the dye then was salted out from the alkaline solution by the addition of sodium chloride (10 to 15 grams); yield, 4.5 grams. The sodium salt so obtained was yellow and dyed silk a clear lemon-yellow. Acidification of its aqueous solution precipitated the free dye acid. 2,4-Diaminophenyl Oxide A mixture of 250 grams of iron powder, 1 liter of water, and 20 to 40 cc. of concentrated hydrochloric acid was heated at 80" to 100' C. under a reflux condenser and vigorously stirred while 100 grams of the dinitro derivative were added in three separate portions in the course of an hour. After heating and stirring for 10 to 12 hours longer, sufficient caustic soda was added to neutralize the acid and precipitate the iron. The mixture was boiled for 15 to 20 minutes, filtered hot through a vacuum filter, the iron sludge washed with hot alcohol and then with benzene, to dissolve all diamine, the washings added to the first filtrate, the 6
Bcr., 49, 1446 (1896).
combined filtrate and washings treated with 120 cc. of concentrated hydrochloric acid and 10 grains of sodium bisulfite, the mixture thoroughly agitated, to collect all organic bases in the acid layer, which latter mas then separated, filtered, and evaporated under reduced pressure to small volume. The crude diamine hydrochloride which crystallized out was dissolved in the minimum quantity of boiling alcohol, an equal volume of benzene added, the solution heated to boiling, filtered hot, and the filtrate allowed to cool slowly. The hydrochloride of' the diamine separated in beautiful pearly plates, which softened a t about 190' C. and were completely melted a t about 210' C. Another crop was recorered by concentration of the mother liquor. The hydrochloride was practically insoluble in benzene, but readily soluble in water or alcohol. Crystallized from alcohol alone, it mas generally contaminated with colored oxidation products, but the addition of one or two volumes of benzene to the alcohol served to keep these contaminants in solution. It was treated with the calculated amount of caustic soda solution containing some sodium hydrosulfite and the mixture extracted with hot benzene. Evaporation of the benzene left the crude diamine base, which was purified by crystallization to constant melting point from the same solvent, and then appeared in colorless or pale grayish diamond-shaped crystals, m. p. 67" C. (cor.), which have not darkened appreciably after standing for over a year; yield, 68 grams. Analysis. Calculated for C ~ Q H I ~ O N C,Z72.0; : H, 6.0 per cent. Found: C, 71.90, H, 5.98 per cent.
The crude base may be purified also by distillation under diminished pressure. Its basic properties are weak. I n water i t is very slightly soluble, but dissolves more or less rcadily in alcohol, ether, or benzene. The dinitro ether was reduced to the diamine also by the use of alcoholic stannous chloride and hydrochloric acid a t 50" to 60" C., but the removal of the tin as sulfide proved quite troublesome. The filtrate from the tin sulfide containing the hydrochloride of the base was worked up as described above and yielded the same prodcct A mixture of 18 grams of iron powder, 1 gram of concentrated (37 per cent) hydrochloric acid, 250 cc. of water, and 23 grams of 2-nitro-4-aminophenyl ether was refluxed for 4 hours while vigorously stirred. Caustic soda (2 grams) was added the mixture filtered, the filtrate extracted with hot benzene, the benzene extracts dried, and the solvent removed; yield of diamine (m. p. 87" C.), 18 grams. .Diacetyl Derivative
Colorless crystals, from water or 50 per cent alcohol, m. p. 171' C. (cor.). Analysis. Calculated for C I B H I ~ O ~ N C,~ 67.60; : H, 5.63 per cent. Found: C, 67.83; H, 5.57 per cent.
Phenoxy Bismarck Brown
A solution of 1.44 grams of sodium nitrite in 5 cc. of cold water was poured into a solution of 7.08 grams of the diamine hydrochloride in 3500 cc. of water while the mixture was stirred vigorously. After 20 minutes' further stirring, the dye was salted out; yield, about 5 grams. It was purified by suspension in water, salting out again, and crystallization from alcohol containing a little hydrochloric acid. It separated in blue-brown crystals, difficultly soluble in water, but dissolving easily in alcohol to a deep brownish red solution, and was a very weak base not freely soluble in dilute acids. Its dilute alcoholic solution dyed silk from a pale orchid-brown to a dark red-brown.
Phenoxychrysoidine
A solution of 2 grams of aniline in 6.3 grams of concentrated (37 per cent) hydrochloric acid and 150 cc. of water was diazotized a t 0" C. by the gradual addition of 1.48 grams of sodium nitrite in aqueous solution, and was then allowed t o stand a t 0' C. for half an hour longer with frequent stirring, to complete the reaction. To it was added slowly 8 cold (0' C.) solution of 4.3 grams of the diamine in 25 grams of 10 per cent hydrochloric acid, followed by a solution of 20 grams of sodium acetate in 200 cc. of water. After stirring for 30 minutes longer the mixture was heated to boiling, filtered, and the dye precipitated from the filtrate by the addition of sodium chloride; yield, 5 grams. The dye so obtained appeared in reddish brown crystals, difficultly soluble in water, and dyed ~ ~ o or o lsilk direct brownish yellow to brown shades. 2,4-Dinitrophenyl Sulfide
Potassium thiophenolate was prepared by melting together 14 grams of potassium hydroxide and 5 cc. of water, pouring this into 25 grams of thiophenol, boiling the mixture gently until it solidified, drying 12 hours at 100" C. under reduced pressure, and pulverizing the pale grayish solid so obtained. This was mixed gradually in a mortar with 46 grams of 2,4-dinitrochlorobenzene, and the grinding and mixing were continued until the reaction appeared complete. After standing for 12 hours it was washed with cold dilute sodium hydroxide until the washings were only pale yellow. The residual reddish brown tar was ground up with sand and extracted with boiling 80 per cent alcohol. As the alcoholic extract cooled, crystals separated, which were recrystallized by dissolving in boiling acetone, adding alcohol until the solution clouded, then clearing it again with a few drops of acetone and allowing the solution to cool; yield, about 20 grams. Instead of acetone, benzene was used also with good results. The thrice-crystallized product formed pale yellow needles, m. p. 117" C., easily soluble in acetone or benzene, less readily in alcohol, and practically insoluble in water. When impure, the compound gradually darkens in the air. 2,4-Diaminophenyl Sulfide
A well-stirred mixture of 13 grams of the dinitro compound, 15 grams of iron powder, 5 grams of concentrated hydrochloric acid, and 250 grams of water was refluxed for 3 hours or longer, made alkaline with caustic soda, refluxed another half hour, and filtered. The sludge was extracted thoroughly with alcohol, the combined filtrate and extracts acidified with excess of hydrochloric acid containing some sulfur dioxide, and the alcohol distilled. After the residual aqueous solution had been extracted three times with benzene, to remove yellow impurities, it was decolorized by a suitable carbon, and then neutralized with ammonium hydroxide solution containing some sodium sulfite. The precipitated diaminosulfide was removed, washed, dried, and crystallized from benzene or alcohol. From the former, it separated in pale yellowish, narrow prisms; from the latter in shorter and thicker prisms; yield, 15 per cent or better. Thrice crystallized, it melted sharply at 107' C., and was soluble in alcohol or benzene, but not appreciably so in water. When pure and dry it did not darken or change color in the air. Anulysis. Calculated for CllHtzSNz: C, 66.67; H, 5.56 per cent. Found: C, 66.42; H, 5.54 per cent.
Phenylthiochrysoidine
The phenyldiazonium chloride solution was prepared from 4.3 grams of aniline dissolved in 11 grams of concentrated hydrochloric acid and GO eo. of water and diazotized
INDUSTRIAL AND ENGINEERING C H E M I S T 2 Y
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below 5’ C. with an B ~ U W U Ssolution of 3.2 parts of sodium nitrite. After standing for another half hour a t this temperature, tests showed aniline still to be in slight excess. This solution was then poured slowly into one of 10 grams of the diaminosulfide in 500 cc. of water and 5 grams of concentrated hydrochloric acid a t 0” C. A well-cooled solution of sodium acetate was poured in gradually until
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the dye was all precipitated as a deep red, flocculent solid and the supernatant liquid was nearly colorless. It was purified by washing first with salt water and then with pure water. It was difficultly soluble in water or dilute acids, but dissolved easily in alcohol. Wool and silk were dyed orange-yellow by it. Its hydrochloride crystallized well from dilute alcohol.
Vitamins in Canned Foods’ V-Peaches By Edward NATIONAL C!ANSERS
F. K o h m a n , Walter H . Eddy, Victoria Carlsson, and Nellie Halliday
ASSOCIATION, WASHINGTON, D. C.,
AND
TEACHERS COLLEGE, COLUMBIA UNIVERSITY, NEWYORK, N. Y.
Vitamin C
N A previous report’ it was stated that apples canned with their normal oxygen content lose all detectable amounts of their vitamin C; that apples in which the gas was replaced by commercial nitrogen lose practically all their vitamin C upon canning; and that apples exhausted of their oxygen content by the respiratory process, as is now generally done commercially, lose no detectable amounts of vitamin C upon subsequent canning. In order to determine if a similar relationship holds in peaches, as well as to secure information as to their normal vitamin content, a study of peaches was made for which the following five lots were canned in California in July; 1924. A4fter the preliminary treatment described for each lot, the peaches were all canned by the following procedure: The peaches were filled into No. 2 cans, which were then filled with boiling water, exhausted 6 minutes a t 88’ C. in a steam exhaust box, and, after being closed, cooked for 15 minutes a t 100’ C., and then water-cooled. This was the regular procedure in the plant where the canning was done.
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Lot 166. The peaches were hand-peeled, halved, and pitted, subjected t o a vacuum of 735 t o 775 mm. (29 to 29.5 inches) twice, and the vacuum released each time with commercial nitrogen after passing it through an alkaline solution of pyrogallic acid. Lot 167. The peaches were halved, pitted, and lye-peeled by the regular commercial procedure. Lot 168. The peaches were halved, pitted, hand-peeled, and held 8 hours under a 2 per cent sodium chloride solution a t ordinary temperature. At the end of this time their oxygen content was reduced t o zero. Lot 169. The whole peaches were held under water overnight (13 hours). At the end of this time their oxygen content was zero. They were then given the regular commercial treatment described under Lot 167. Lot 170. The peaches were picked at the same time and from t h e same trees as the peaches in the previous lots, but were not fully ripe, but rather in the stage suitable for shipping. Two days after picking they were put in cold storage, where they were held for 4 days. They were then beld 3 days in t h e canning factory, when they were in the proper state of ripeness for canning. They were then canned by the regular procedure given for Lot 167.
During August, September, and October, 1924, peaches were purchased daily on the New York markets for feeding in the raw state and after “home cooking.” For this “home cooking” the peaches were peeled, halved, and then cooked 1 Presented in part under the title “Vitamins in Raw, Home-Cooked, and Canned Peaches” before a joint session of the Divisions of Biological and Agricultural and Food Chemistry at the 69th Meeting of the American Chemical Society, Baltimore, Md., April 6 to 10, 1925. Received December 15, 1825. 2 Kohman, Eddy, and Cartsson, THISJOURNAL, 16, 1261’ (1924).
in a loosely covered kettle with a reasonable amount of water. It required about 7 minutes for them to come to boiling and the boiling was continued for 8 minutes. During February to July, 1925, inclusive, the various lots of canned peaches were fed. For vitamin C studies the raw peaches were fed in 2.5, 5, 10, and 20-gram amounts; the “home cooked” in 5, 10, 20, and 40-gram amounts; while the’five lots of canned peaches were fed in 3, 5, 10, and 15-gram amounts daily. From three to nine guinea pigs were fed each amount. Control pigs were fed the basal diet only to demonstrate absence of vitamin C . Composite growth curves are given in the accompanying chart. The experimental period was 90 days. However, two of the pigs on 2.5 grams raw peaches died of scurvy in 61 and 79 days, respectively; the three pigs on 5 grams of home-cooked peaches died in 33,74, and 75 days, respectively; while two of the three pigs on 10 grams of home-cooked peaches died in 65 and 69 days, respectively. Therefore, the latter part of these three curves represents only two animals. All the pigs on all amounts of the canned peaches survived the 90-day period, although all but two of the fifteen pigs receiving only 3 grams showed definite symptoms of scurvy on autopsy, as well as two out of nine pigs receiving 5 grams of the peaches from Lot 167. Judging from these facts, as well as the appearance of the individual animals coupled with their growth curves, the following conclusions seem warranted: 1-The minimum antiscorbutic dose of raw and canned peaches is close to 5 grams per day per guinea pig, although a somewhat larger amount gives better growth. With the possible exception of Lot 167, in which no attempt was made t o remove t h e oxygen, 5 grams of canned peaches gave better results than 5 grams of the raw peaches. It should be noted t h a t this gives no clue as t o the extent of any appreciable destruction, since we have no data on the original vitamin content of the peaches used for canning. 2-There is a n indication that removal of oxygen from peaches previous to canning gives some protection t o vitamin C, but the extent is practically insignificant. These peaches contained about 1.2 per cent by volume of oxygen. 3-Ten grams of open kettle-cooked peaches have no more vitamin C than 2.5 grams of raw peaches, and considerably less than 3 grams of canned peaches. Probably the raw and canned peaches contain about five times as much vitamin C as the kettlecooked peaches. 4-Picking the peaches somewhat green and allowing them t o ripen off the tree for several days previous t o canning seems to make no difference in their vitamin C content.
I n the writers’ experiment with apples they found evidence of some vitamin C destructive factor other than elementary oxygen, which can be eliminated by making use of the respiratory process and which therefore seems to be loosely
