1056
INDUSTRIAL AND ENGINEERING CHEMISTRY
efficiency of potassium chlorate may probably be accounted for by the following reactions: 6R’NH3+
+ 6C1- + KCIO3 +6R.NH2 + KCl + 3Hs0 + 3C11
“The preceding representation indicates that there will be a temporary diminution of the hydrogen-ion concentration because of the formation of un-ionized water as a result of oxidation* * * It is also known t h a t in the absence of acidity, potassium chlorate in aqueous solution would not exert the oxidizing effect which takes place. The decomposition of chlorate depends, therefore, on the presence and reaction with hydrogen ions.” Regarding these conclusions Vorozhtzov states: “The explanations given by Groggins for the favorable action of potassium chlorate and other oxidizing agents is incorrect. The reaction mass is alkaline and, therefore, hydrochloric acid which is present as ammonium chloride should not react with potassium chlorate. (The reaction velocity of hydrochloric acid with potassium chlorate is directly proportional to the cube of the hydrogen-ion concentration,) The favorable action of oxidizing agents should rather be attributed to the fact t h a t they oxidize the reduced P-aminoanthraquinone and by doing so improve its quality, or to the fact t h a t they oxidize ferrous ions to ferric and thus prevent the reducing of 0-aminoanthraquinone.” Unfortunately, no experimental data are presented by Vorozhtzov which might throw light on this subject and which, admittedly, is a fruitful line of research. The reference to the hydrogen-ion concentration necessary to decompose potassium chlorate is hardly germane to aminations carried out in iron autoclaves. His explanation involving the oxidation of reduced anthraquinone is unlikely and contradictory because it presumes that the chlorate is f i s t inactive and then active and does not account for its decomposition. The important fact is that, under the optimum conditions previously reported ( 5 ) ,the chlorate does react and disappears slmost completely. Furthermore, Vorozhtzov’s admission t h a t the chlorate is decomposed and that an oxidation actually takes place rather confirms and strengthens the authors’ hypothesis: The decomposition of chlorate depends on the presence and reaction with hydrogen ions. The fate of the chlorine in the suggested mechanism of reaction is not definitely known. It may (1) directly or indirectly oxidize the iron surfaces of the autoclave, and (2) oxidize some of the amine, evidence of which is generally obtainable and frequently apparent.
VOL. 28, NO. 9
Experiments conforming to optimum operating conditions show t h a t there is 6.5 per cent decomposition of the chlorate when the autoclave contains only aqueous ammonia, potassium chlorate, and ammonium chloride, but when 2-chloroanthraquinone is also present, there is a virtual disappearance of chlorate on completion of a 20-hour run a t 200’ C. Similar experiments in open flasks reveal that the percentage of chlorate decomposition is approximately six times as great for aqueous solutions of ammonium chloride plus potassium chlorate plus iron as for corresponding ammoniacal solutions. It is thus apparent that chlorate reacts appreciably only when a n oxidizable compound-e. g., iron or a n i l i n e i s present. Furthermore, it is probable that this decomposition of chlorate occurs in a neutral or acid medium, or on surfaces covered with hydrogen or ammonium‘ions. Calcott (1) found t h a t “certain acid inhibitors of the type pyridine, quinoline, and thiocarbanilide, etc., also produce similar beneficial results” in ammonolysis and has concluded that “apparently any material which strongly inhibits t h e solution of iron under the conditions existing in amination, would also improve yield and quality of product.” T h e theories relating to the efficacy of acid inhibitors are ably summarized by Mann and co-workers (6). It is generally agreed that inhibitor molecules reduce the rate of discharge of hydrogen on the cathodic areas of iron and thus inhibit its solution. Why acid inhibitors are useful if the charge is alkaline, as Vorozhtzov contends, is a subject for study and speculation.
Literature Cited (1) Calcott, W. S.,E. I. du Pont de Nemours & Co., private communications, Jan. 6, 1932, and Dec. 27, 1935; patents applied for. (2) Groggins, P. H., and Hellbach, R., Chem. & Met. Eng., 37, 693 (1930). (3) Groggins, P. H . , and Stirton, A. J., IND. ENG.CHEM.,25, 42 (1933). (4) I b i d . , 25,46 (1933) ; Groggins,lbid., 25, 274, 277 (1933). (5) Groggins, P. H., and Stirton, A. J., Ibid., 25,169 (1933). (6) Mann, C. -4., Lauer, B. E., and Hultin, C. T., Ibid., 28, 159 (1936). (7) Vorozhtzov, N. N., Jr., Anilinokras Prom., 4 , 3 3 2 (1934). (8) Vorozhtzov, N. N., Jr., and Kobelev, V. 9., Compt. rend. acad. sci., U. R. S. S.,3, 108 (111-14, English) 1934. (9) Vorozhtzov, N. N., Jr., and Kobelev, V. d.,J. Gen. Chem. (U. S. S. R.),4, 310 (1934). RECEIVEDMay 5 , 1936. Contribution 262 from the Industrial Farm Products Research Division.
Composition of Petroleum Wax B.J. MAIR AND S. T. SCHICKTANZ National Bureau of Standards, Washington, D. C. HE composition of wax from petroleum or allied substances has been the subject of many investigations. That such wax generally contains a large percentage of normal paraffin hydrocarbons seems to be well established. Francis, Watkins, and Wallington (3), for example, found that twenty-one fractional distillations of wax from a Scotch shale oil separated it into constant-boiling fractions. Piper, Brown, and Dyment (6) measured with x-rays the “spacings” of Francis’ wax fractions and found that they agreed with those of the synthetic normal paraffins. They concluded that these fractions were composed of hydrocarbons identical in constitution with the normal paraffins. However, in addition to fractions composed of normal
paraffins, several investigators have obtained wax fractions, the melting points of which were far below those of the normal; paraffins and which consequently were not composed of a mixture of normal paraffins. By fractional crystallization from ethylene chloride of narrow-distillation cuts of wax from a Midcontinent petroleum, Ferris, Codes, and Henderson ( 8 ) obtained several series of fractions; each series was composed of fractions of substantially the same molecular weight and boiling point. These investigators concluded that the more insoluble fractions were made up of normal paraffins, since their melting points and refractive indices agreed closely with those for synthetic normal paraffins. The melting points of the more soluble fractions xere, howel-er. about 30” C. lower than those
SEPTEMBER, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
1057
TABLEI. PHYSICAL PROPERTIES OF WAX FRACTIOXS -Data
50%
boiling Melting point a t point 10 mm.
G./ml.
Q./mole
,
0.7717 0.7711 0.7703 0.7706 0.7728 0.7819 0.7841 0.7856
420.5 409 407 400 402.5 409.5 407 401 410
0.7889
402
Refractive index a t Density 80' C. a t 80' C.
Fraction
Type of crystal
c.
c.
6A 6B 6E 6F 6G 6H 61
Plate Plate Plate Plate Plate Malcrystalline Malcrystalline Needle Needle
65.5 63.6 62.8 60.6 55.8 50.9 46.3 42.1 38.8
291 282.5 278.5 275 275 276 283 284 287
1.4310 1,4305 1,4301 1.4300 1.4313 1.4332 1.4349 1.4359 1.4365
6J
Seedls
34.0
281.5
1.4375
6C 6D
Mol. weight
Data Obtained in This Laboratory-------Combustion analysis Ratio, Mass of I n the formula C+Hm + I moles Hg0 sample less to mass of Mol. z admoles C o t C H weight n z justed"
Obtained by Ferris, Cowles, and Henderson-
....
+
{ ....
%kp?! G./mole ~ ::!] : ~ 426.0~ .... .... .... ....
.... .... ....
.... .... ....
....
.... ....
... ...
... ...
... ..*
...
~
30.0
.. .. .. ..
..
.. ..
~
1.84 , .
.. .. .. .. .. *.
2.22
.. .. .. ..
....
Acid Iodine No.b
S0.b
2.5
..,
. . . . . .
. . . . . .
. . . . . . ... . . . . . . . . . .
......
{ l1.0107 ,olol
o,oo13} 0.0013
409.3
29.1
0.60
0.67
0.4
2.8
{l,oo51 1.0050
0.0048 o,oo39)
411.6
29.2
0.28
0.51
1.1
...
Value of z sdjusted for loss of H on oxidation (see text). b These determinations were made by the Detergents Section of the Bureau of Standards.
0
of the corresponding normal paraffins. These fractions were thought to consist of isoparaffins, principally because their molecular refraction agreed with that computed for the series CnHzn-2. Clark and Smith (1) made an x-ray diffraction study of some of the waxes of Ferris, Cowles, and Henderson, and concluded that the higher melting waxes were composed of normal paraffin hydrocarbons. From the fact that the diffraction patterns of the waxes became less sharp as the melting point decreased, these authors concluded that the waxes melting considerably below the corresponding normal paraffin hydrocarbons contained a large proportion of isoparaffinic material. More recently Xuller and Pilat ( 5 ) ,by crystallization of the wax from a Boryslaw petroleum asphalt, obtained fractions melting a t lower temperatures than the corresponding normal paraffin hydrocarbons and showed that they contained cyclic constituents; one fraction has the formula C A l n - 3.1. THROUGH the kindness of the Atlantic Refining Com-
Q)pany which supplied several samples, the writers were able
to test by combustion analyses three of the wax samples of Ferris, Conles, and Henderson to determine whether they also might contain cyclic constituents. An accuracy of approximately *0.0006 in the ratio, moles of water t o moles of carbon dioxide, was usually obtained in the combustion analyses. The atomic weights used in the computations were 12.009 for carbon and 1.0081 for hydrogen. The molecular weights were determined by a n ebullioscopic method previously described (4). Table I shows values for the physical properties of one series of wax fractions determined by Ferris, Cowles, and Henderson, together with values derived from the combustion analyses of three of these samples in this laboratory. Fractions 61 and 6J give values for x,in the formula CnHan + =, which are much smaller than the z = 2 required if they consisted of isoparaffins, while the value x = 1.84 for fraction 6A is also somewhat low for a normal paraffin. These samples are not composed entirely of carbon and hydrogen (column 9, Table I). The difference between the weight of the sample and that of their carbon and hydrogen components may be assumed to be due to oxygen acquired by the sample since the time of its preparation by Ferris, Cowles, and Henderson. Such an oxidation, if it resulted in the formation of alcohols, would cause no loss of hydrogen and no change in the value of x but, if it resulted in the formation of acids or of aldehydes or ketones, would cause a loss of hydrogen and a decrease in the value of z. It is necessary to determine whether the oxygen in these samples is sufficient to account for the deviation of the z values from +2, Each gram
atomic weight of oxygen introduced per gram molecular weight of wax would cause, in the case of acids, a decrease in the value of z equal to 1, and in the case of aldehydes or ketones a decrease in the value of z equal to 2. The maximum possible correction for oxygen, applicable only if all the oxygen were present in aldehydic or ketonic form, gives the values for z shown in Table I, column 12. This procedure undoubtedly overcorrects for the presence of oxygen, since some of the oxygen (from about 12 to 20 per cent) is present in acidic form (column 13) and some may be present in alcoholic form, Moreover the x value for sample 68, corrected in this manner, is now 2.22 which is impossibly high. However, even with this correction the values of z for fractions 61 and 6J are still much below that required of isoparaffins. That this deviation of z is not due to the presence of unsaturated hydrocarbons is shown by the iodine number (2.8) of fraction 61, which is sufficient to account for a decrease of only 0.09 in the value. Although fraction 6A is composed of the series CnHzn+ 2, it is evident that fractions 61 and 6J are composed of about 70 and 75 per cent, respectively, of molecules of the series CnHZn (or correspondingly smaller amounts of molecules of the series CnHZn-2,CnHQn-(, etc.) and, therefore, contain cyclic constituents. The results of these measurements, although confirming the conclusions of Ferris, Cowles, and Henderson that the waxes melting a t nearly the same temperatures as the normal paraffin hydrocarbons are composed of normal paraffins, show that, in agreement with the findings of JIuller and Pilat, those which melt about 30" C. below the corresponding normal paraffins are composed chiefly of cyclic hydrocarbons.
Literature Cited Clark, G. A., and Smith, H. B . , IND. EXG.C H E ~ I23, . , 697-701 (1931). Ferris, S. W., Cowles, H. C., Jr., and Henderson, L. hi., Ibid., 21, 1090-2 (1929); 23, 681-8 (1931). Francis, F., Watkins, C. hl., and Wallington, R. IT., J . Chem. SOC.,121, 1529-35 (1922). h'lair, B. J., Bur. Standards J . Research, 14, 345-67 (1935). Muller, J., and Pilat, S., J . Inst. Petroleum Tech:, 21, 887-94 (1935). Piper, S. H., Brown, D., and Dyment, S., J . Chem. Soc., 127, 2194-2200 (1925). RECEIVED April 15, 1936. Publication approved by the Director, National Bureau of Standards. Financial assistance for this work was received from the research fund of the American Petroleum Institute as part of Project 6. on "The Separation, Identification, and Determination of the Constituents of Petroleum."
