INDUSTRI4L AND ENGINEERIXC CHEMISTRY
654
The average number of milliliters of 0.021 N ceric sulfate necessary to oxidize the nitrites in the presence of cobalt was practically eleven-twelfths (10.8/12)of that necessary when cobalt was removed-i. e., the cobalt accounts for the oxidation of one of the twelve nitrite equivalents in the precipitate. This confirms the results of Drushel ( 3 ) and others ( 2 ) 6, '7, 8, 11) and establishes the factor 6.52 as empirical for a precipitate of the composition KZSaCo(X0&; its identity with the stoichiometric factor for a precipitate of this composition is merely coincidental. An explanation of the relation may be found in the fact that a variability in the composition of the precipitate between KNa&o(KOz)6 and K 2 ~ a C o ( S o 2 )as6 a result of variations in the conditions of precipitation has been noted by several investigators (8-12, 14). It is possible that the precipitate in this procedure approaches the relative composition Kl.~aSal.16Co(Tu'Oz)6, which is the approxiinate formula for which the factor 6.52 is stoichiometric in the presence of cobalt. No analyses have been made of the composition of the precipitate, and the above formula is merely suggested as a possible means of explaining a seemingly empirical relation. Until the actual composition of the precipitate formed in this procedure is determined, the factor 6.52 must be considered as empirical. The procedure is of definite practical importance, especially when applied to soil extracts, and while the nature of the precipitate and the character of the factor are of interest, the practical application of the procedure should not be neglected because of any obscurity as to the theoretical considerations latent in the method.
VOL. 10, NO. 11
Acknowledgment The authors thank W. H. Pierre, formerly head of the Department of Agronomy and Genetics a t West Virginia University, now head of the Department of Agronomy a t Iowa State College, G. G. Pohlman, head of the Department of Agronomy and Genetics, and R. S. Marsh, head of the Department of Horticulture, a t West Virginia University, for their suggestions and criticisms of the work. They also acknov-ledge the assistance of the American Potash Institute in financing the project of which some of this work is a part.
Literature Cited (1) hdie, R. H., and Wood, T. B., J . Chent. SOC.,77, 1076 (1900). (2) B o w e r , L. T., J. IND.ESG. CHEU.,1, 791 (1909). (3) Drushel, W.A., Am. J . Sei. (Ser. 4),24, 433 (190i). (4) Harris, H. C., Soil Sci., 40, 301 (1935). ( 5 ) Hubbard, R. S., J . Riol. Chem., 100, 557 (1933). (6) Kramer, B., Ibid., 41, 263 (1920). ( 7 ) Kramer, B., and Tisdall, F. F., Ibid., 46, 339 (1921). (8) Lewis, A. H., and Marmoy, F. B., J . SOC.Chem. I n d . , 52, 177T (1933). (9) (10) (11) (12)
Lohse, H. TV., ISD. ESG.CHEJI.,Anal. Ed., 7, 272 (1935). Morgulis, S.,and Perley, A., J . Biol. Chern., 77, 647 (1928). Piper, C. S., J . SOC.Chem. I n d . , 53, 392 T (1934). Robinson, R. J., and Putnam, G. L., ISD.ENG.CHEX.,Anal.
Ed., 8, 211 (1936). (13) Schueler, J. F., and Thomas, R. P., Ibid., 5, 163 (1933). (14) Tan Rysselberge, P. J., Ibid., 3, 3 (1931).
RECEIVED May 9, 1938. Published with the approval of the Director of t h e K e s t Virginia Agricultural Experiment Station as Scientific Paper No. 206.
Microscopic Identification of Some Important Substituted Naphthalenesulfonic Acids WILLET F. WHITMORE
T
Ai%D ARTHUR
I. GEBHART, Polytechnic Institute of Brooklyn, Brooklyn,N. Y.
HE commercial importance of the naphthalenesulfonic
acids has resulted in numerous methods for the identification of these difficultly characterized compounds. I n most cases their salt-forming properties have been utilized in preparing metallic or arylamine salts (1, 2, 3, 6-8, 10, I d ) . Chambers and Scherer (4) used the base benzylisothiourea for characterization of a- and 0-naphthalenesulfonic acids and the 1,5-,1,6-, 2,6-,and 2,7-disulfonic acids. Hann and Keenan (11), using microscopic methods with this reagent, reported the optical data on the derivatives of these same acids. The limitation of the above methods is their lack of applicability to large groups of the acids. By a combination of such procedures-metallic salt formation, benzylisothiourea salts, and free acids-Garner (9) outlined a procedure for the microscopic identification of twenty substituted naphthalenesulfonic acids. His method requires the preparation and examination of a number of derivatives of each acid. T h e method which is here reported is based upon the fact that benzoylation of a number of naphthylamine-, naphthol-, and aminonaphtholsulfonic acids yields characteristic, readily isolated test forms. Photomicrographs of the derivatives and the free acids or their sodium salts are included (all of the same magnification, approximately 70). The latter two are generally poorly described in the literature and are in many cases character-
istic and serve as additional proof of identity. Optical data are given for the derivatives.
General Procedure PURIFICATION OF SAMPLES.A11 acids insoluble in mater are dissolved in strong sodium carbonate solution and treated with activated carbon (Darco). The free acid precipitated with hydrochloric acid is filtered by suction, washed with a little cold water, reprecipitated similarly a second or third time, and dried at 40" t o 50" C. In what follows, unless otherwise noted, this is the purification procedure used. PREPARATION OF BENZOYL DERIYATIVES.For monosubstituted acids-naphthylamine- or naphtholsulfonic a c i d s 4 . 2 gram of the acid or its sodium salt is dissolved in 10 ml. of spproximately normal sodium carbonate solution in a 125-ml. glass-stoppered Erlenmeyer flask and 0.2 ml. of benzoyl chloride (reagent quality) added. With disubstituted acids such as the aminonaphthol type the quantities of sodium carbonate and benzoyl chloride are doubled; otherwise the procedure is the same. Contrary to usual procedure, sodium carbonate appears to serve better than sodium hydroxide for the benzoylation, the derivative frequently precipitating more easily when the carbonate is used. KO trouble is experienced from gaseous carbon dioxide, as it is absorbed in the excess of carbonate used. The flask is stoppered and vigorously shaken until all odor of benzoyl chloride has disappeared. This may take as long as 5 minutes in some cases and a precipitate may or may not form, depending on the sulfonic acid.
SOI-ERIBEK 13. 1938
.\\.kLYTIC.\L
FIGCRE 1. Left.
EDITIOS
l - N . 4 P H l ~ H l - L . ~ h f I S E - ' T - ~ ~ L F O S IACC I D
Free acid from h o t solution
Center.
655
(CLEYE'S A C I D 1,7)
Free acid f r o m cold solution
Ripht
Rerizoyl derivative
If a precipitate forms, it is filtered by -uction. : Sufficient fine solid c. P. sodium chloride is added to the filtrate to make about a 20 per cent saline solution. If more precipitate forms, i t is collected with the original and the filtrate is diecarded. This salting-out procedure is necessary only if it is desired to increase the yield; otherwise the original precipitate is used and the filtrate discarded immediately. If no precipit'ate forms during benzoylation, the above salting-out procedure is applied. Rarely is a concentration of more than 20 per cent of salt required for complete precipitation. The derivative is removed from the filter and dissolved in 10 mi. of water, warming to 40" C. if necessary to aid solution. A small amount of Darco is added and the solution is filtered, cooled, and salted out as before. This reprecipitation is repeated (eliminating the Darco after the firsb time) until the filtrate is neutral to phenolphthalein. rsually two or three recrystallizations are sufficient. The precipitate is spread on a porous plate and dried in a desiccator. Oven drying tends to darken the derivatives in some cases.
If precipitated too rapidly-that is! if too much salt is addedno characteristic crystals are obtained but merely an indefinite mass of poorly defined forms. If too little salt is added crystallization is unduly prolonged o r does not occur a t all. Under ideal conditions a slight cloud of crystal nuclei appears 5 or 10 minutes after Ti-arming,,gron-ing in 10 or 20 minutes more to a small amount of crystalline precipitate that' settles to the bottom of the tube. A small amount of the precipitated crystals and mother liquor is now transferred to a slide, using a glass tube of about 2-mm. bore. (This size of tube prevents breaking up some of the large spherulites frequently found.) Appearance is the final test of proper precipitation. If indefinite forms are obtained, a new precipitation should be made using less salt. Any deviations from the above procedure will be noted. BENZYLISOTHIOURE.~ DERIVATIYES.T w of the fifteen acids ctudied ( H and R acids) do not yield insoluble benzoyl derivatives but are readily characterized by means of benzylisothiourea. ( a t the outset of this ivork attempts to make general use of this reagent for characterizing all the acids failed in the majority of cases.) RECRYGTALLIZATIOS OF DERIVATIVES FOR ~IICROSCOPICThe reagent, is prepared by the method used by Chambers and Sclierer ( 4 ) by adding, with stirring, 126.5 grams of benzyl EXANIXATIOS. To m a k e the method generally applicable, chloride to a solution of 76 grams of thiourea i n 200 ml. of 40 per a standard crystallization technic has been developed and is cent alcohol and warming 15 minutes o n the steam bath. On applied as far as possible. Adherence to this procedure gives cooling, the benzylisothiourea separates and is recrystallized consistently reproducible test forms. Appreciable deviations several times from 40 per cent alcohol (ni.p. 176" C.), The derivatives are prepared by dissolving 0.1 gram of the yield unsatisfactory or misleading results. Crystallizations sulfonic acid, or its sodium salt, and 0.2 gram of benzylisothiourea on the slide d o not generally permit of sufficient control of separately in 5-ml. portions of approximately 0.2 N hydroconditions. chloric acid. Both solutions are heated to boiling and mixed. Upon cooling rapidly the derivative separates as a white crysA 1 per cent solution is made by dissolving 0.02 gram of the talline precipitate. I t is filtered, recrystallized once from 6 nil. dry derivative in 2 ml. of water in a test tube, warming if necesof hot 0.2 S hydrochloric acid, and dried. sary to effect solution. After cooling to room temperature, fine For microscopic examination the derivative is crystallized from or powdered c. P. sodium chloride is added in very small amounts a hot 1 per cent solution in 0.2 dV hydrochloric acid by cooling ( 5 mg. a t a time), shaking until the portion added has dissolved until crystal nuclei just form, then allowing to stand a t room before adding more. This addition of salt is continued until the temperature until a moderate amount of crystals has formed. solution becomes slightly cloudy, indicating that precipitation of the derivative has begun. The solution is now warmed to reT h e properties and description of the acids studied and dissolve the precipitate and set aside to cool. crystallization their derivatives are given in Table I. T h e purification prooccurs in from 15 minutes to an hour if the salting out has been cedure is t h a t applied to the acid or its sodium salt (whichproperly performed.
FIGURE 2. Left.
1-xAPHTHYLAMINE-6-sULFOSICACID(CLEVE'B ACID1,6) Center. Free acid from cold solution Right. Benzoyl derivative
Free acid from hot solution
TABLEI. PROPERTIES OF SAPHTHALEXEFree Acids or Sodium Salts Substance 1 Naphthylamine - 7 - sulfonic acid (Cleve's acid 1,7)
-
Purification procedure Usual
Physical appearance Pure acid, flesh-colored with slight lavender cast
- Saphthylamine - 6 - sul-
Usual
Pure acid, light flesh color
1
-
Solution in sodium carbonate on standing overnight deposits dark material which is filtered off before precipitating free acid
Pure acid, pink
2
-fonic Naphthylamine - 6 - sulacid (Bronner's acid)
Usual
Pure acid. light flesh color
2
- Naphth
lamine - 1 - sulfonic acicf(Tobias acid)
Usual
Pure acid, Dink color
1
- Naphthylamine - 4 - SUI-
Usual
Pure acid color
1
fonic acid (Cleve's acid 1,6)
- -
Uaphth lamine 5 sulfonic a c i 2 (Laurent's acid)
fonic acid)
acid
(naphthionic
-
-
Naphthol 6 - sulfonic acid (Schaeffer's acid)
2
-
-
sulfonic Saphthol - 4 acid (Nevile and Winther's acid)
1
i
Yery light flesh
..........
- , -SUI-
Vsual
Pure acid, flesh-colored
rsual
Pure acid, light gray, almost white
-
2,s Aminona h t h o l - 6 - SUIfonic acid (&amma acid)
Indefinite
Strong aqueous solution Purified acid is light gray color treated with Darco and 61tered. Filtrate acidified with hydrochloric acid and evaporated t o dryness on steam bath. Residue extracted with 90% alcohol and alcohol evaporated
Pure acid, light gray
-
Long prisms. much multiple twinning from dilute solution. B y adding excess of free acid t e sodium carbona t e solution filtering and acidifying slightly wiih dilute hydrochloric acid, diamond shaped plates form. Occasional hexagonal plate Dendrites with occasional spherulite of rectangular needles
..........
Usual
Aminonaphthol fonic acid (J acid)
Elongated eight-sided plates Indefinite and octahedra from concentrated solution. Considerable clustering and multiple twinning
Dissolving sodium salt i n least Pure sodium salt is white amount of hot water, treating with Darco and filtering hot. On cooling considerable salt crystallizes. Complete precipitation obtained b y adding sodium chloride. Recrystallized similarly
1,8 - Aminonaphthol- 4 -suifonic acid (9 acid)
2.5
Microscopic Appearance Hot solution Cold solution Almost square rectangular Irrewular plates not as large or plates from concentrated s&aIe as from hot; also solution dendritic clusters From concentrated solution From dilute solution diafirst mass of narrow recmonds almost exclusively tangular needles rapidly changing t o square crystals n i t h occasional diamond .......... Clusters and rosettes of long narrow rods irom dilute solution. If solution is too concentrated, crystals very small
.......... -
Diamond shaped crystals from dilute solution; also a few dendritic clusters of long rectangular rods
nuclei appear, allowing t o stand a t room temperature, dense spherulites of needles form with occasional radiating narrow rectangular dates Precipitating from very concentrated solution with solid sodium chloride, tiny, almost rircular flqwerlike particles form which eyhibit no apparent crystalline structure
From dilute solution lonq slender needles inclined t o cluster in dendritic forms
Featherlike crystals from dilute solution
..........
temperature. Occasionally a n indefinite rosette is also seen
..........
From concentrated solution masses of short fine needle; considerably clustered
-
Rapidly cooling, saturated aqueous solution of sodium salt, short fine needles formed
..........
-
Adding escess of sodium salt t o cold water, warming t o dissolve and cooling rapidly, glistening ,elongated rectangular prisms iormed
- Naphthylamine - 6 8 - di-
Acid dissolved in least amount Pure acid is light cream color of warm water. After cooling, precipitated b y adding absolute alcohol and reprecipit ated simil arly 2 Naphthol - 3,6 - disulfonic Sodium salt digested a i t h Pure sodium salt is light cold 80% alcohol and alcocream color acid (Racid) hol discarded. Salt dissolved in small amount of water. treated with Darco. filtered, and precipitated by adding 95% alcohol 2 Naphthol - 6,s disulfonic Sodium salt dissolved in least Pure sodium salt is white amount of hot water, alcoacid (G acid) hol added t o about S O % strength and solution treated a i t h Darco and filtered. Sodium salt precipitated by adding ether t o filtrate and reprecipitated similarly Acid sodium salt dissolved in Pure acid sodium salt is pale 1,8 Aminonaphthol 3,6 hot water treated with green, almost white disulfonic acid (H acid) Darco, filtlred, and precipitated from filtrate by adding alcohol. Reprecipitated Pimilasly 2
sulfonic acid acid)
-
(amino G
-
-
Short narrow rectaneular rods showing some denarites and spherulites by rapidly cooling concentrated aqueous solution
....
SULFOSIC
ACIDS AXD THEIRDERIVATIVES Optical D a t a on Derivatives Sign of Extinction elongation no no Parallel Negative 1.685 1.606
7 -
During preparation Soluble. Addition of moderate amount of salt giyes light oink lustrous Drecivitate ~. Forms rapidly as pink floating precipitate. .Uot readily soluble in cold water Soluble. Moderate amount of salt gives pink precipitate
Forms as flesh-colored precipit a t e , not readily soluble in cold water. Salts out easily
Forms slonlv a3 white precipit a t e , readily soluble in water b u t precipitated by small amount of salt
Forms very slowly as small amount of granular pink precipitste. Addition of considerable salt gives heavy precipitate Forms rapidly as granular white precipitate, Not readily soluble in water and precipitates with a small amount of salt
Forms instantly as gray gelatinous precipitate, moderately soluble in u.ater, salts out readily
Solution rapidly turns yellow a n d derivative forms as grayish gelatinous precipitate, readily soluble in water but precipitates with small amount of salt
Characteristics of Benzoyl Derivatives Microscopic appearance Masses of shield-shaped plates clustered in beautiful rosettes Rectangular plates, some fairly large. in rosettes
Smaller ones inclined t o cluster
Parallel
When first formed consists of large oval plates considerably clustered Parallel changing rapid1 t o large masses of piled-up plates with practicall; no individuals, %ut frequently showing parts of what appear t o be elongated hexagons. Compensation not obtainable with certainty due t o piling up and lack of indviduals. Indices of refraction readily obtained on broken fragments Dimorphous. (a) B y usual salting out procedure dendrites of long bayonet- Parallel sha ed crystals form B cooling hot 1 % aqueous solution until precipitation starts, t x e n allowing t o stand a t room temperature, plates varying from sauare t o elongated rectangles obtained. If crystallization has been rapid longer forms predominate Extinction poor a n d occasional isotropic crystal seen. Most views Pnrallel show one brush of a biaxial interference figure. I n several hours t o a day crystals revert t o form , a ) Fan-shaped clusters of long rods. At times spherulite of rods seen Parallel
Positive
1.628
1.646
1.633
1.576
Negative
Slightly under 1.71
1,612
Positive
1 543
1 620
Negative
1 703
1.63'2
(E)
Masses of diamond or rhomb-shaped plates closely clustered. Indi- Obli%ue 38 viduals rare. I n position of extinction crystal 80 aligned t h a t direction through acute angles is parallel t o cross hairs. Indices of refraction are given for crystals oriented in these ppsitions. Slow component of crystal perpendicular t o long direction. clean-cut face observed crystal angles are apparently 76' and 10:' Fan-shaped fernlike clusters of tiny rectangular needles, best recrystal- Parallel liaed from boiling 1% aqueous solution adding few drops of alcohol if necessary for solution, and allowing t o cool a t room temperature
Precipitated in usual manner microrrystala of very little character obtained. Adding 20% sodium chloride solution dropwise t o cold 0,25% aqueous solution of derivative until slight cloud forms, same microcrystals obtained: if alloa-ed t o stand overnight with test tube uncorked, upon shaking vigorously glistening rhomb-shaped plates form. Rhombs difficult t o obtain as precipitation conditions are critical. Dilute solution, very little sodium chloride, prolonged standing, and violent agitation assist in formation. Extinction given when long edge of rhomb aligned with cross hair. I n cleancut crystal face observed crystal angles are apparently 70.5' and 109.5O. Refractive indices taken in misture of methylene iodide and carbon tetrachloride. Slow component of crystal makes 30.6' angle a i t h long direction of crystal I.ar_oeiuzLy 3iraerlihe ipi:eru:l-es w i [ ! i I.rtle cryi'alliiie chsisrter \\:.en On standing a day ,r sr, mr,dera-ely large I.eeiiles first p:e,:.pirared. : i > ~ n isuiraile , fcr ci):aining r,;,tiraI d ~ r a . Ii er2ur. sl2aly t,y ziddiiiq ZOyo sodium chloride solution dropwise t o cold 0.25yo aqueous of derivative until faintly cloudy, upon keeping overnight with test tube uncorked, very dense spherulites of needles with thick radiating prisms obtained Dense spherulites a n d dendrites of long flexible needles distorted into curved forms hy cover glass. If crystallized more slowly by adding one drop,of 20% sodium chloride solution t o 2 ml. of 1% cold aqueous solution of derivative, same form obtained b u t needles stronger
..
Parallel .io:ulrle. Salted ou: rapid:? is gummy. bur l i sal: a d d e l [ o ir..~ipientprecipirar!~na d a!loaed :u .rand hali h o u r CTYStalline precipitate obtained Benzoylation occurs rapidly Salt must be added very slowly t o precipitate only trace of crystal Parallel nuclei. Upon standing several hours it appears as black dots, esa n d liquid foams like soap tremely dense spherulites of microneedles. Individuals f r o m broken solution. Derivative only masses, although small, suitable for obtaining optical data. If cryspartially precipitates but tallized too rapidly a useless gummy mass results small quantity of salt gives pink, lustrous, gummy precipitate, readily soluble in water. E v e n when precipitated slowly gummy product obtained which crystallizes on standing overnight Parallel Soluble. Separates as bulky Extremely long flexible needles clustered t o resemble tufts of hair white precipitate upon adding considerable salt
9
1.653
1.537
6
1.628
1.646
i
1.654
1.460
8
Segative
1,684
1.662
Positive
1 629
1.696
Positive
Oblique 30.6'
Parallel
Figure
Segative
0ve r 1 71
1.624
Negative
1.691
1,510
12
Negative
1,681
1,54i
14
1.592
1 694
15
Benzoyl derivative very soluble a n d cannot be satisfactorily salted out. Benzylisothiourea readily forms insoluble derivative and is used for characterizing acid Soluble. Separates as bulky white precipitate upon adding considerable salt
Extremely long rods resembling derivative of 2-naphthylamine-I-su1ionic acid but longer and less clustered
Parallel
Benzoyl compound very soluble a n d cannot be salted out. Benzylisothiourea readily forms insoluble derivative a n d is used for characterizing this acid
Crystallized from lY0 solution dense spherulites of long narrow needles. Fast component of crystal makes 17' angle with long direction
Oblique li0
..
IUDUSTRIAL AXD EUGIUEEHI\G CHEhIISTRl
658
2 1
3
4
FIGURE 3. ~-NAPHTHYLAMIR-E-~-SULFOSIC ACID (LACREST’SACID) 1. I.
Free acid from cold solution Benzol1 d e r n atiye as first precipitated
FIGURE 4.
3. 4.
Benzoyl derixatire after standing Benzol1 d e r n ative, another view
2-SAPHTHYL.4MISE-6-SCLFOSIC
1 OL. 10, KO. 11
ever is the more usually met Tvith or easily handled) before preparing the derivative. The designation “usual” refers to precipitation from sodium carbonate solution with hydrochloric acid, referred to above. The physical appearance of the pure acid or salt is stated in the third column. Unless otherwise noted, the free acids were precipitated with dilute hydrochloric acid (1 t o 3 of mater) from their solution in sodium carbonate. The microscopic appearance of the benzoyl derivatives is described, after recrystallization by the standard procedure outlined, or as stated in the table. I n the section under Optical Data on Derivatives indices of refraction are taken in the two positions of extinction and are noted as n, and no. K h e n the long direction of the crystal is aligned with the 6 to 12 o’clock cross hair, the refractive index has been designated as no (ordinate) ; when aligned tvith the other cross hair, as na (abscissa). For crystals showing oblique extinction, the first position (15’) is no, and the next (105’) is n,. These refractive indices do not necessarily correspond t o w and E or a,p, or y but are more readily obtained. They are taken in mixtures of methylene iodide and xylene n i t h white light a t 20” C.
ACID (BROKSER’SA C I D )
I.eft.
Free acid from hot solution Center. Benzoyl derivative crystallized from salt solution Right. Benzoyl derivative crystallized from a a t e r
Left.
FIQURE 5. 2-NAPHTHYLAMIXE-1-sULFONICACID (TOBI-46 ACID) Free acid from cold acid solution Center. Free acid from cold almost neutral solution Right. Benzoyl derivative
ASALYTICAL EDITIOX
&-OVEMBER 15. 1938
659
I n general, interference figures are not readily observable in the orientations visible.
Separations by lMeans of Benzoyl Derivatives The varying solubilities of the derivatives suggested the possibility of separating various acids b y this means. Table I1 summarizes the solubilities of the benzoyl compounds studied. A trial separation based upon the solubilities shown in Table I1 n-as made by benzoylating a mixture of 0.2 gram each of 1-naphthylamine-7-sulfonic acid and 2naphthol-6-sodium sulfonate in the usual manner, using proportional amounts of reagents. PRECIPITATE. The precipitate was filtered by suction, washed nith a little cold water, dissolved in 20 ml. of Ti-arm water, cooled, precipitated with the least possible amount of salt, and reprecipitated similarly a second time. When recrystallized for microscopic examination in the usual manner it showed the characteristic fan-shaped clusters of the benzoyl derivative of Schaeffer's acid (Figure 7 , 2 ) . FILTRATE. Salt was added until a slight precipitate formed which was filtered off and discarded (to remove any residual derivative of Schaeffer's acid). The bulk of the derivative was then salted out and recrystallized as usual until neutral. When recrystallized for microscopic examination shield-shaped rosettes
2 1 l-SAPHTHYLAlfIXE-4-SULFOSIC ACID (NAPHTHIONIC .kCID) 1. Free acid from cold solution 7. Benzoyl derivative
F I G ~ R6.E
1 2 2-SAPHTHOL-6-SFLFONIC -ACID (SCHAEFFER'S ACID) Sodium salt from cold saturated solution 2. Benzoyl derivative
FIGURE 7. 1.
LefL.
FIGURE 8. I-NAPHTHOL-4-SELFOSIC A C I D ( S E V I L E ASD Tq'ISTHER'S .iCID) Free acid salted out from cold concentrated solution Center. Benzoyl derivatire as first precipitated Right. Benzoyl deril-aril-e after standing
FIGURE 9. Left.
~ , & A ? d I N O X . i P H T H O L - 4 - ~ U L F O N I CACID
(S ACID)
Free acid from cold solution Center. Dibenzoyl derivative, ordinary precipitation Right. Dibenroyl derivative grown slowly from dilute solution
660
INDUSTRIAL AND ENGINEERISG CHEMISTRY
VOL. 10, NO. 11
of the benzoyl derivative of Cleve’s acid 1,7 were obtained (Figure 1, right).
2
4
1. 2.
FIGURE10. 2,5-AUISONAPHTHOL-7-sCLFOSIC A C I D (J A C I D ) Free acid from hot dilute solution 3. Dibenzoyl derivative Free acid from cold dilute solution 4. Dibenzoyl derivative precipitated more slowlg
FIGURE 11.
This result indicates t h a t clean-cut separations are possible. I n this study no unusual types of compounds were prepared or new or unusual syntheses involved in the preparation of derivatives. I n addition, many of the compounds which were made were isomeric and consequently it was felt that a n a l y s e s of t y p e compounds would be satisfactory and representative of groups. Analyses were made of the following types: a monobenzoyl compound, a dibenzoyl compound, and a benzylisothiourea derivative. Iiitrogen was determined by the Kjeldahl method and sulfur with the Parr bomb. ~ ~ O S O B E N Z O Y L DERIVATIVE. 2-Benzovlnaphthylamine-1-sodium sulfonate (CloHa.S03Xa.NH.C0.CaH6). Nitrogen calculated, 4.02 per cent; found, 3.89 per cent. Sulfur calculated, 9.17 per cent; found, 8.99 per cent. DIBEXZOYL DERIVATIVE. 2,5-Dibenzoylaminonaphthol-7-sodium sulfonate [C,,H,.SO,r\’a.NH.O.ICO.C,H,‘)ol. Nitrogen calculatid, -2:98 per cent; found, 3.08 per cent. Sulfur calculated, 6.8 per cent; found, 6.63 per cent.
1 2 2,8-AlfISOXAPHTHOL-6-SCLFOSIC ACID (GAMMA ACID) 1. Free acid by cooling hot solution 2. Dibenzoyl derivative
FIQURE 12 (Right). 2-NAPHTHYLAMISE-6,8-DISULFOSIC ACID (AMIXOG ACID) 1. Free acid from cold solution 2. Benzoyl derivative
1
2
NOVEMBER 15, 1938
FIGERE13.
661
ANALYTICAL EDITION
2-?jAPHTHOL-3,6-DISULFOSIC A C I D
(R ACID)
Left. Sodium salt from hot concentrated aqueous solution Center. Benzylisothiourea derivative from 1 per cent solutipn Right. Benzylisothiourea derivative from 0.5 per cent solution
TABLE11. SOLUBILITIES OF BENZOYL DERIVATIVES Acids Not Precipitated during Beiizoylation 1-Naphthylamine-7-sulfonic acid (Cleve's acid 1 , 7 ) , precipitates with a moderate amount of salt l-?;aphthylamine-5-sulfonic acid (Lament's acid), precipitates with a moderate amount of salt 2,5-Aminonaphthol-7-sulfonic acid (J acid), precipitates with a moderate amount of salt 2,8-hminonaphthol-6-sulfonic acid (Gamma acid), gummy precipit a t e with a moderate amount of salt 2-Naphthol-6,8-disulfonic acid (G acid), requires a large, amount of salt for complete precipitation 2-Naphthol-3,G-disulfonio acid (R acid), only a small amount of precipitate with saturated salt 1,8 - Aminona hthol- 3,G disulfonic arid ( H a c d . cannot be salted out
Acids Precipitated during Benzoylarion 2-Saphrhylamine-1-sulfonic acid BEXZYLISOTHIOUREA DERIVATIVEOF ~-SAPHTHOL-~,~-DI- (Tobias acid), readily soluble in water, salts out easily SELFOKIC ACID [CloHj.0H(S0,H.NH2.XH:CS.CH2.CaH~)2]. 1-Kaphthylamine-6-sulfonic acid Nitrogen calculated, 8.81 per cent; found, 8.70 per cent. (Cleve's, acid 1,6), not readily soluble in water Sulfur calculated, 20.00 per cent; found, 20.12 per cent. 2-iXaphthylamine-6-sulfonic acid (Bronner's acid), difficultly soluble in cold water Summary and Conclusions I-Naphthol-4-sulfonic acid (Nerile and Winther's acid), moderately soluble in water, salts out readily A rapid and relatively simple method has been developed 2-Naphthol-6-sulfonic acid (Schaeffer's acid), very difficultly soluble for the microscopic identification of a number of important in cold water. not verv soluble in hot naphthylamine, naphthol, and aminonaphthol sulfonic acids 1,8-.lminonaphthol-4-sulfonic acid by means of their benzoyl derivatives. (S acid), readily soluble in water, precipitates with a small amount of salt
2
1
FIGERE14. 1.
WID (G ID)
2-KAPHTHOL-6,8-DISuLFOSIC
Sodium salt from saturated aqueous solution
2.
Benzoyl derivative
-
The procedure has been standardized so as to be applicable to the entire group of acids; only small amounts of material are required. The benzoyl derivatives offer a possible method of separation of some of the acids. The characteristics and microscopic appearance of fifteen of these sulfonic acids and their derivatives have been tabulated, including optical data for the latter, and photomicrographs of characteristic forms have been prepared.
Literature Cited Ambler, J. IND.ENQ.CHEM.,12,1080(1920). Ibid., 12, 1194 (1920). Ambler and Wherry, Ibid., 12, 1086 (1920). Chambers and Scherer, Ibid., 16, 1272 (19241.
Forster,'Hanson, and Watson, J . SOC.Chem. I n d . , 47, l 6 5 T (1928). Forster and Keyworth, Ibid., 43, 165T (1924).
/bid., 46, 25T (1927). Garner, S. SOC.Dyers Colourists, 43, 12 (1927). Ibid., 52, 302 (1936). Green and Vakil, J. Chem. SOC.,113, 35 (1918). Hann and Keenan, J . Phys. Chem., 31, 1082 (1927). Lynch, J. IND.EXG.CHEM.,14,964 (1922). RECEIVED March 28,1938.
2
1
FIGURE1s. 1.
1,8-~~~INONAPHTHOL-3,6-DISELFONIC ACID(H A C I D ) 2. Benzylisothiourea derivative
Acid sodium salt from hot water
An abstract of a thesis submitted t o t h e faculty of t h e Polytechnic Institute of Brooklyn in June, 1937, b y Mr. Gebhart in partial fulfillment of the requirements for the degree of master of science in chemistry.
