86
ORGANIC A K D BIOLOGICAL.
rotation of freshly dissolved crystalline fructose. I t is thus proved t o have the same cause as the mutarotation reaction, namely, the slow establishment in solution of the equilibrium between the u and forms of the sugar. From the stereochemical theory a formula is deduced which allows the calculation of the rotatory power of the unknown forms of many of the natural and synthetic glucosides. From these calculated values the theory permits a calculation of the influence of the end groups of the glucosides on the rotator!- power of the asymmetric carbon atom to which they are attached. The results, which are shown in the figure, indicate t h a t the influence of the group is chiefly due to its weight, and t h a t the rotation of the affected carbon atom changes greatly with the weight for introduced groups of small weight but is constant for those of large weight. The specific rotations of the unknown a-&fructose and the unknown forms of mannose, maltose, melibiose, xylose, and lyxose are calculated. [PHOENIX PHYSICAL LABORATORY CONTRIBUTIONS,KO. 17.1 THE CHANGE IN REFRACTIVE INDEX WITH TEMPERATURE. I. BY K. GEORGEFALX. Received September 28, 1908.
X considerable amount of work has been done on the determination of the refractive indices of a number of organic liquids a t different temperatures.’ Briihl and W. H. Perkin used this change in refractive index with change in temperature as a means of following the equilibrium between the two forms of certain tautomeric substances. Their results in some instances do not agree.’ It was decided, therefore, to attempt to follow these changes more carefully by determining the refractive indices for the sodium and the three hydrogen lines a t intervals of z O or 3 O over a range of 50’ or 60°, using the purest chemicals obtainable and samples from different sources when possible. I n order to be able to judge whether the changes observed with tautomeric substances were normal or not, it was necessary to follow the changes in the refractive indices of other substances with Landolt-Bornstein-Meyerhoffer’sTabellen give a very complete summary. of Temperature on the Refractive Power and on the Refraction Equivalents of Acetylacetone and of Ortho- and Para-toluidine,” J . Chem. SOC.,69, I, concludes with: “It would seem, therefore, that there must be some unnoticed source of error in the refractometer used by Briihl, when i t is employed for temperatures somewhat above those of the atmosphere.” Briihl in “Studien iiber Tautomerie,” J , fir. Chem., 5 0 , 192, referring to the fact that the molecular refraction of acetylacetone as determined by Perkin decreased with rise in temperature, whereas his own experimental observations showed i t to increase, remarked : “Worauf diese Widerspruche beruhen, verrnag icli nicht zu erklaren.”
* Perkin, in his paper un “Influence
CHANGE IN THE REFRACTIVE INDEX WITH TEMPERATURE.
87
change in temperature just as carefully, in order to find the general course of the phenomena in question. In this paper, the method of working is briefly described first, then the experimental results obtained so far are given, then some theoretical conclusions following directly from these results will be discussed, and finally some observations on ethyl acetacetate will be spoken of. Apparatus and Method.-Thanks to the kindness of Professor J. I,. R. Morgan, it was possible to use in this investigation a Pulfrich refractometer with the arrangement for heating the liquid to be studied, belonging to the Department of Physical Chemistry. The heating spirals, etc., supplied with the apparatus were used, and since refractometers of this type have been described a number of times, especially recently in great detail by C. Chhneveau,' who used among other refractometers one exactly similar to the one used here, only a few points in connection with its use will be mentioned. The refractive indices were obtained for the sodium (DJ and the three hydrogen (C, F, and G') lines compared to air a t about 20'. The thermometers used read to tenths of a degree, one between o o and 50°, the other between j o o and 100'. Since the measurements were made over a fairly large range of temperature, i t may be possible that the substance was not always a t the temperature indicated by the thermometer, or that there may be a lag in the refractive index on account of which the true reading could only be obtained after some time. These sources of possible error were overcome by taking the readings a t different intervals of time after the thermometer had become stationary, sometimes making a measurement after a few minutes, in other cases waiting an hour or more, and also by making the measurements around 40° (for instance) in one case by heating from the room temperature upward, and in the other by heating to a higher temperature for some time and then allowing to cool to the lower temperature. No attempt was made to take the readings a t any one fixed temperature determined upon beforehand, but the readings were taken a t the points for which the heating conditions for the time being gave a constant temperature. The time of taking the four readings occupied generally less than two minutes, and the temperature was read both before and after. The temperature did not remain constant to a tenth of a degree for considerable lengths of time, but did within a degree for an hour or more, while for the time required for the readings i t remained practically constant. In this way, it is hoped, constant errors were avoided and by taking a sufficient number of readings between about 20' and 7 j O and plotting the results, the true course of the change within these limits of temperature could be determined. The record of the temperature and the time was of course carefully kept, but will not be given here as no general effect was notice-
' Ann. Chim. fhys. [8],
12,
145.
able except in one case (ethyl wetacetate). Corrections for the zero point were introduced. The corrections for the prism a t different temperatures were taken from the tables furnished b!- Zeiss. The substances for which the measurements were made were diisoamyl, dimethylaniline, n-heptyl alcohol, benzyl alcohol, iz-butyric acid, and the tautomeric substances acet!-lacetone and ethyl acetacetate. The choice of substances may seem peculiar, but in order to find the general course of the change under investigation it was desirable t o use as many different classes of substances as possibie and in picking out the individual member of each class to study, those substaiices with high boiling points lying close together were chosen, since this investigation \vi11 be extended to mixtures (in varying proportions) and their refractive iiidices a t different temperatures, as more light, probably, will be thrown on the state of the tautomeric substances under these conditions than in the study of the pure liquids. The Substances o!>tliined from Kahlbaum viere measured as recek-ed and after distillation, practically the same results being obtained in the two cases. 'J'he other substances were distilled before they were used in some cases? in others not. The boiling points given are not intended to represent accurstely the true temperatures, as the thermometer used was not calibrated careiully and the pressures were not determined, but are only given to show the constancy of the temperatures a t which the substances distilled. The densities were determilied with an Ostwald pycnometer which had been used by Dr. Eric Higgins.' Some time was saved by using the calibration curve for different temperatures as carefullj- determined by him. The densities are compared to the density of water a t 4' and the results of others recalculated to this basis ~vhennecessary, when used for comparison.
Experimental Results. I n this section the results for diisoam!-l, dimethylaniline, 92-heptyl alcohol, benzyl alcohol, ??-butyric aciti, and acetylacetone will be given. On plotting the refractive indices against the temperatures and drawing curves, it was found that for all four lines, as well as for the densities for these substances, the smoothed cur\-es lire straight lines in every case. All points naturally do riot lie on the curves, but the dif-ference is not greater in any case than the difference bet\veen tu-o experimental results. The curves are not reproduced in this paper since the scale on which they would have to be drawn ~ ~ o u not l d s h o ~the details satisfactorily. I t may suffice to give all the experimental determinations here and the equations which represent the curves for all the cases. The results will tie tabulated as follows :
' hhrgot1 and Higgins, Tms J O I J R N . I I , ,
30,
10,ii.
CHANGE IN THE REFRACTIVE INDEX WITH TEMPERATURE.
89
The refractive indices determined for the C, D, F and G' lines. The densities determined. The five equations representing the curves. The experimental results of others compared with those calculated for the required temperatures from the equations. The changes in the refractive indices and in the density for I O as calculated from the equations. The dispersions for ioo and Soo calculated from the equations.
Strictly speaking, the curves hold only as far as experiments have been made as regards the temperature, but i t seems fair to extend them a short distance above and below. The dispersions (and later in the theoretical part, the refractive powers) have therefore been calculated for IO' and for So', in all probability without introducing any sensible errors. The dispersions have been taken from the curves and not from the experiments directly, since the latter may contain the errors due to two series of experiments, while the former eliminate to a great extent these accidental errors. DIISOAMYL. Kahlbaum's, undistilled. C.
D.
21.2 22.3 23.3
1.40589 5 30
25. I
413 378 I99
1,40793 739 717 611 587 399 291 I37
1.
25.8 30.0 32.6 36.2 36.8 40.5 43.0 45.8 47.9 49.9 51.6 52.0
53.7 57.9 61.0 67.0 72
9
512
08j
1,39937 912 754 66 I 515 418 331 249 235 I43 I ' 38963 829 529 26 j
I12
I
'
39948 8jI
716 623 533 442 423 354
F.
204 111
026 1.39930 907
835 646 509
I 60
I
Kahlbaum's redistilled, b. I 56. jO-j.0' t.
C
22. j 23.2 26.0 30.7 37.6 43.7
1.40536
D. I
'
40738
502
702
388 190 I ' 39896 634
588 384 093 I . 39815
I
I 2 j
096 I ' 40907 797 635 617 442 347
0 1f
1'38729 463
G'.
1,47303 243 226
'
.4I742 666 653 547 532 345 227
059 04 I I . 40859 765 64 I 509 429 357 339 269 08 j I
'
39948
211
.....
38936
370
(uncorr.). F.
1.41254 215 IO2
I . 4089 j
593 326
G'. .41687 65 I 527 325 016 I . 40743 I
ORGANIC AND BIOLOGICAL.
90
C.
t.
46.I 51.2 54.7 58.2
281
I11 I.
62.9 67.3 70.3
389j0 742 541
618 390 235
190 1 ' 39965 ROO
627
048
1.39844
420
71s
...
223 089
598
410
G'.
F.
1).
687 4;1 313 160 I . 38932
job
518
DENSITY. Wt. in grams.
Tal. in cc.
IO.0 17 0
23.3 23.j 34.4
IO.OIj1
10.0191 10.0209
43.5
49.9 56.8 62.'3
10.0233 10.0245 10.0258 '~~/1.41j37 +
(10)
(IC)
(~d) (14
7.071
0.7056 0.7008 0.6956 0.6909 o.6852
0.7212 0.7128
t/318j.17j t13173.24 t/312;.03 t/3143.39 t/960
nD/~.4r7j0-
(I!))
0 .j213
7.024 6.973 6.926 6.870
I O . 0220
70.I
df,
7.225 7.224 7.142
n,/1.42280 + ~tG~/1.4271o d,/0.7392 f
+
I
=
I
=
I
=
I
=
DENSITY. Schi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I,achowicz2., . . . . . . . . . . . . . . . . . . . . . . Just3.. . . . . . . . . . . . . . . . . . . . . . . . . . C.
Change per degree.. . . . 0.000444
t.
Found.
Calc.
9.8'
0.7358
0.7317
0.721j6 0.7463
0.7223 0.7223
22.O 2 z . O
G' .
u.
F.
0.0004467
0.000455
D-C. Dispersion, I O O . . . . . . . . . . . . . . . . o.oo210 Dispersion, go0.,. . . . . . . . . . . . . . o.00191
DIMETHYLANILINE. Merck's (mono-free), undistilled. I.
C.
17.6 20.0
25.4 30. I 34.0
F.
11. I. jj968
840 5 74
345 I 60
43.7 52.9
I . 54681
63.I
1.53695 655 259
64.I 71.3 Ann., 220, 88 (1883). Ibid., 220, I 72 (1883). a Ibid., 2 2 0 , 156 (1883).
201
d.
0.0004j-+ o . o c q 7 G' - F. F-D. 0.00430 0.00522 0.00437 0.00464
CHANGE IN THE REFRACTIVE INDEX WITH TEMPERATURE.
91
Kahlbaum’s, undistilled. 1.
C.
D.
20.0
21.0 27.0 30.7 30.8 37.9 42.0 45.7 55.8 56.2 62. I
i.
18.4 24.6 27. I
32.5 34.8 37.9 41.5 44.4 47.3 49.4 52.3 52.6 58.9 59.3 64.3 65.3 65.8 67.3 67.7 69.6 73.4
F.
1.57752 744 720 629 596 323 I34 096 I . 56716 508 303 I . 55820 766 489
17.9 18.0 18.6
Kahlbaum’s redistilled, b. 1 8 9 . 5 ~(uncorr.). D. F. I . 55250 1,54959 847 570 448 284 103 1.53962 806 C.
721
603 586 265 256 I . 52988
62 7 581 555 467 456 35 I 156
931 911 827 806 724 511
334 281 263 I 80
I54 050 1’ 54842
The determination of the G’ line, especially a t the higher temperatures, was rendered difficult by the yellow color of the dimethylaniline. DENSITY. i.
21.3 36.2 43.3 53.4
1’01. i n
cc.
10.0167 I O . 0195 10.0208 10.0227
Wt. in gmsb
di.
9.567 9.448 9.390 9.310
0.9551 0.9429 0.9371 0.9289
O K G A S I C AXD BIOLOGICAL.
92
i 31jj.0j i/,3143. 19
=
I
=
I
/'30ji.32
=
