J. BISHOP T I N G L E A N D II. F. K O E L K E R .
822
droxyazo compounds described by Hewitt and Pope.' This led to tlic belief t h a t it might be the sulphate of benzeneazochlorphcnol. Water was poured over it, the mixture heated slightly and filtercd. The resulting coinpound was found to be benzeiieazoorthochlorphenol. 'l'lie sulphuric acid in the water was determined. Calculated for C,,H,N,C10. H,SO,: H,SO,, 30. or). Found : H,SO,, 2 9 ,
'I'he formation of this compound is undoubtedly due to the sapoiiitication of the hydrazone a t first formed, the resulting oxyazo colnpound tllr.11 combining with the sulphuric acid originally present in the hydrazinc. sulphate to forrii the correspoiiding sulphate. IVIiile thc hydrochlorides of a nuniber of tliv hydrosyazo compouiids haye b c c ~prepared, so far a s I know, this is the first sulpliate to be describcd. Othcr quiiiones gave similar results, so that this method of prcpratioii would . be a gcneral one for tlie prepratio11 of the siilpliates of t h e hydrosynzo compounds. COLUMBUS, O H I O .
STUDIES IN NITRATION, !K2-MELTING POINT CURVES OF BINARY MIXTURES OF ORTHO- META- AND PARANITRANILINES: A NEW METHOD FOR DETERMINING THE COMPOSITION OF SUCH MIXTURES. BY J. BISHOPT I N G L E A N D H. F. ROELKER. Received March il 1go8.
During the last academic year the senior author, in conjunction wit11 Dr. 17. C. Rlanck, carried out a somewhat extensive investigation o f tlir nitration of N-substituted aniline derivatives. In the course of this work, the results of which have been awaiting publication, in thc rlnicrzcu?~ Chemical Journal since the middle of August, 1907, the need was frequently felt for a simple, expeditious method for the determination of the coniposition of mixtures of the isomeric nitranilines. Moreover, for our purpose, it was necessary t h a t the method should be applicable to rclatively small quantities of material. The only processes of which wc. have been able t o find descriptions in the literature consist of rccrystallizations, accompanied, in some cases, by conversion of one or more of the nitranilines into some simple derivative. Apart froin the question of their accuracy, such methods did not appeal to us because they ccrtainl!. invoh-e a considerable amount of labor, and probably demand for their successful operation a relatively large quantity of material. Besides their differences in solubility, the nitranilines vary somewhat in color, in their strength a s bases, and, quite widely, in their melting-
' Rer., 30,
1624.
Bishop Tingle and Blanck, A m . Chem. J . , 36, 605 (r9oG).
STUDIES I N NITRATION.
823
points. The color of the compounds, especially in dilute solutions, appeared t o be too nearly alike for our purpose, and a determination of the partition of acid between the isomers involves too much trouble, consequently we decided t o investigate the curves produced by plotting the melting points of binary mixtures of the nitranilines against the composition. In this connection we should like t o mention that A. F. Holleman has been for some time engaged with the investigation of the influence of water on the course of nitration of benzene, acetanilide, etc., and he has also studied the influence of substitution in the benzene nucleus. In the course of a paper with C. H. SluiterZ he gives a brief tabular statement of the melting points of a few mixtures of p-nitracetanilide and dinitracetanilide. I n another communication, with which we were not acquainted until after our own work was in progress, he speaks of “perhaps being able t o determine the composition of binary mixtures of aromatic nitro compounds by reading off from a curve the depression in the melting point of A caused by the addition of varying quantities of B.” As will be seen from the contents of our paper, such a mode of procedure is inapplicable t o mixtures of the nitranilines and is essentially different from the plan which we have adopted. Holleman also describes briefly and without working details, a “method of extraction,” which is applicable t o the determination of the composition of ternary mixtures in general.3
Experimental. Materials.-The nitranilines were obtained from Kahlbaum, they melted a t 7 1 ” , 114’ and 1 4 7 O , the temperatures given in the literature for the 0-, m- and p-compounds, respectively. Before use they were recrystallized from gs per cent. alcohol, in such a way t h a t half of the substance employed remained in the mother liquor. This treatment produced no change in the melting point. The alcohol employed in the experiments described below was the ordinary commercial 95 per cent. I t was filtered before use. Preparation of Mixtures.--A weighed quantity of each nitraniline was dissolved separately in alcohol, a t the ordinary temperature; the solutions contained about z per cent. of ortho- and metanitraniline, respectively, but in the case of the para derivative the concentration was only about I per cent. The quantities of each solution required t o produce a mixture of the composition desired were run out from a burette and the alcohol evaporated on the water bath. In some cases the evaporation was allowed to take place a t the ordinary temperature. The residue was then placed in a desiccator on filter paper, allowed to remain 2
Ber., 39, 1715 (1906). Kec. trav. chim., 26, 2 0 8 (1906). Rep. Congres. chim. Phurm. Lzege., p. 2 8 Julv. ~ I ~ O L
824
J. BISHOP TINGLE ASL, i l . F+rROELKEK.
about 24 hours and the melting-point determined. lTresh solutions were made u p each day a s required. Orthonitraniline is very slightly volatile at the ordinary temperature and, like the other isoiners, vaporizes somewhat with boiling alcohol. The magnitude of the error introduced in this manner cannot be very great, because mixtures of similar composition, prepared by evaporating the alcohol a t the two temperatures nientioned, always showed the same melting point. bIoreovcr, mixtures which had bee11 wrapped in filter paper and exposed t o the air showed no change in their iiielting point after several months. .is will be seen from the tables, the composition of the mixtures which we cmployed varied by intervals of 2 per cent. During the course of this work we had reason to suspect the accurac). of the statements made in the literature regarding the so1ubilit)- of the nitranilines and we therefore rnadci the following dcterminations. Scparate portions of the three isomers were mixed with quantities of alcohol insufficient for complc~tesolution, and the liquids wrc. maintained for about 30 minutes, a t 40°, in a thermostat. The clear solutions were then decanted and allowed t o cool slowly t o 15'. Xfter reriiainiiig for a time at this temperature, in contact with the crystals which liatl separated, io cc. of each clear liquid was withdrawn b!- means of a pipctte, tlic solutions allow tl t o evaporate a t tlie ordinary temperature. and the rcsicluia dried in a desiccator. At I jo,I O cc. of tlie respective solutions, in c i j per cent. alcohol, contain I , j 8 4 j grams of ortho-, o 4960 gram of incta- a'nd o,+o3o gram of paranitranilinc, respectively. '~'.\BLI;
POINT ; 01;MIXTCRZS 1. ~ - ~ I B I . T I N C
01' ORTHO-AXII
Per cent. Per cent. Per cetit. 31. p. ofortho. 31. p. of ortho. 11.p. ofortho.
68,;'
78
OS o o
70 7.1
O;
CJ'
/ J ~ . u O
72
61.0~
70
60.6' 58.0~ 57.3' 55.5O 55.4'
68 66 64 62 60
55.3' 55.0'
54.8' 54.6' 54 0' 55.4' 55.6' 55.7' 55.8'
56,5'
31. 1).
METAKITRANILINES. Per cent. of ortho.
31.
p.
57.5'
IS
107.0°*
56.j'
j8 36
60.2'
16
56.8'
,i4
58.2'
14
I08.0'* 109,oo*
.iS
56.6'
56 54 52
56.8'
J?
57,s'
12
IIO.0'*
50 1.8 46 -1-4 42 40
57.0' 57.3' 5j.6' 55.0' 55.6' 59.2'
30 28
57,2'
I0
III.OO*
26
24 22 20
64.0' 70.4' 80.0' 57.8' 104.0'
S
I08.0'*
G 4
109.oo* I I I . 5'* I I2
.o'*
'l'he nldtiizg @ids wert' determined in the ordinary manner; the theriiionieter employed was a "standard " one, capable of being read t o o . I '. 'l'he ternperaturc of the bath was usually raised rather rapidly uiitil i t Firas WTithin 25' of the melting point of the substance under examination, after which thc increase was about 8' per minute. S o difficulty was csperienced in obtaining constant results, eve11 when the coiiditioris iyerc somewhat varied. In certain cases, which are duly n o t r d , it was
STUDIES I N NITRATION.
825
found t o be desirable t o determine the temperature a t which the substance gave clear globules on the sides of the melting point tubes, because for the mixtures mentioned this was much more definite than the point a t which the material melted completely and collected a t the bottom of the capillary. This procedure does not affect the use of the curves for quantitative purposes. The temperatures marked are those a t which the substances melted completely (see above). These mixtures, containing from 2 0 t o 2 per cent. of orthonitraniline, became clear and globular a t temperatures higher than those required t o produce the same effect in the case of specimens containing a higher proportion of ortho compound ; consequently this change of standard does not invalidate the use, for analytical purposes, of the curve given below. In Fig. I , the data contained in the above table are plotted in the form of a curve.
*
In Table I1 are given the melting points of mixtures of meta- and paranit raniline. The mixtures marked became clear and globular (vide Table I) a t the temperatures given, but did not melt completely. In a few cases the melting-point was not sharp, therefore we determined the limits of temperature within which the substance liquefied and give the mean value
*
T A B L E II-h'lELTING
POINTS O F hIIXT[lRES O F LIST.\- .\NU I'.\R.\SITR.\SILINE.
Per cent. Per ceiit. Fer ceiit. I> e r cent . of meta. 31. p. of meta. 31. p. of meta. &I. p , o f m e t a . 31, I I I . jo
7s
110.j'
76
111.00
71
IIo.Oo
72
107.j o
70
106 oo
6Y
1).
Per cent. of ineta. 11. p.
r0-I..so
66 64 1 0 7 . 0 ~ 62 106.0~ Go 110.j'
in the tahlc; these figures are marked 1. So far as we have becn able to test the question, we have found these ternpvraturc limits t o he constant. The 30 per cent. mixture was almost, Iiut not coiiipictcly, nielted a t I IS. jo, whereas that containing 46 per cent. of m e t n derivative behavcd exactly like a pure compound. l'he data in 'l'ablc I1 are reproduced in the curve ITig. 2 . Alixtures of ortho- and paranitraniline melt in a highlv irregular manner aiid t h e curve prepared from our data is quite unsuited for analytical
.. (00'
Fig. ?
S T U D I E S I N NITRATION.
827
purposes. A t first we were inclined t o refer this irregularity t o the presence of moisture, but this is hardly probable because the pure constituents, after exposure t o air, exhibit the correct melting points quite sharply; moreover, all our mixtures were treated in exactly the same manner, so t h a t the disturbing factor should have affected each one t o an equal extent. I n order t o make certain of this point, however, some of the mixtures were dried with very special care, but no alteration was apparent in their melting points. It may be added t h a t of the mixtures showing the more pronounced irregularities, various specimens were prepared a t different times, but the results were unchanged. The mixtures which exhibit the most marked breaks in the curve (containing 58-68 per cent. of ortho compound) do not contain the constituents in any simple molecular ratio. At present we have no explanation t o offer of the reason for the irregularities in question. It may be t h a t they have a casual connection with the well-known simultaneous production of ortho and para disubstituted benzene derivatives and they are decidedly reminiscent of the alternate rise and fall shown in the melting point of the aliphatic monobasic acids. We are a t present investigating this question more fully. Application of the Melting Points for Analytical Purposes. An inspection of the curves for the ortho- meta- and meta-para-mixtures shows t h a t the direct determination of the melting point would be sufficient, within some regions of temperature, to demonstrate the composition of a substance containing either of these constituents in unknown proportion. Within a greater range of temperature, however, there are a t least two mixtures of widely differing composition which have identical melting points. In such cases the determination is made a s follows: Assuming t h a t the material under examinatioii consists of ortho- and metanitraniline, a portion of it is mixed with a n approximately equal quantity of, say, pure metanitraniline, and the melting points of this mixture and of the original material are determined simultaneously, on the same thermometer. If the original material melts a t a higher temperature than it does after the addition of metanitraniline, its composition is indicated by a point on the left side of the curve, otherwise by the corresponding position on the right-hand branch. If pure orthonitraniline is used for mixing, these relationships will be, of course, reversed. I n the case of the meta-para-curve the addition of pure parunitraniline will lower the melting points of a mixture whose composition is situated t o the left of the eutectic point, whereas the remaining possible mixtures, to the right of it, will have their melting points raised by the addition of the pure para compound. Admixture with pure metanitraniline will, necessarily, reverse these relations. It will be obvious that the quantity of pure isomer which is added is
828
W. J. KARST,.\KT:
. \ X I ) \V.
J. .\IORGAS.
of no particular importance; we have found it convenient to take a n amount approxiinatel!, equal t o that of the Inaterial u:idc.r e?ia!iiination. The method has been tested b y tlic junior author, who recciwtl a number of mixtures, tlic coi-iposition of each of \vhicli \vas u n k i i o ~ r to ~ i liin:. His results were accurate to 2 pc'r cent. and ill so:i:c cases agreed c v r ~ i more closely. In dealing with ternary mixtures it is advisable to crystallize then1 fractionall). from alcohol once o r t\vic.i.. 111 this 1i:uniler \ve have foulid that we could obtain two portions, one containing substantially all t lie orthonitraniline together with soiiie iiieta-, \vliile the other portion consisted of the nieta- and paraisoniers. \lye. i i a l ~~ n a d ea few esperiii:cnts on the separatioii of ortho- arid paranitraniline by cr!.stallizatiori. So far as we can judge, the separdtion ciiii l x 1i:;ldc yuantitativcl!.. 'l'hc mixture is weighed and treatctl with just sullicielit boiling alcohol (9j per cent.) to dissolve it. \lTliciic.001, tlie i.oluliic is i::easurcd. l'he paranitraniline which deposits is collected am1 to its w i g h i is 2:dded that of the quantity dissolved in the filtrate; tlie sum of thesc, subtracted froill the weight of thc original material, rcpr 111s the orthonitraniline.
Summary, I. Curves have been constructed slio\ving the relationship between the melting points and t h e co~npositionof tlie three binary iiiixtures of the isomeric nitranilines. 2. In the case of the mixtures of ortho- aiid nicta- arid of nieta- and paranitraniline, these curves arc comparatively regular; they fall t o t h e eutectic point aiid then risc t o thc ilielting point oi the pure coiiipouiid. 3. The curL-e representing tlie relationship 1 ) e t w e i l the nielting point and composition of mixtures of ortho- and paranitrariiline is highh. irregular. At present it is impossible to givc a satisfactory explanation of this phenomenon. 4. 'l'he curves ineiitioned ubovc c u i bel used to deterriiiiic tlic coinposition of inixturcs of otho- aiid n!eta-- arid of iiicta- aiid paratiitranilinc, respecti\-ely, by a simple aiid c.spcditious iiict hod which requires aril!, :i 1lii1limal quantity oi iiiatvrial. ' 1 ' 1 1 ~ results arc usually accuratt withiii two per ceiit. McMASTER UNIVERSITY,
TORONTO, CANADA. December, 190;.
__ -SOME DERIVATIVES OF I,~-DIMETHYL-~,~-DINITROBENZENESULPHONIC ACID, BY
W ,J. K A K S L A K K A N 1 ) 11'. J . M O K C A N . lieceireil .\larch to. 190'
'l'he illilia1 material u s ~ t l\vas the potassiui~i salt of i .~-diiiietliyl-~,Odinitrobenzene-1-sulptionicacid, nhicli was prepared :is follows :' 800 1
Claus and Schmidt. b'. 19,1424.
