December, 1923
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
1233
T h e Lubricant and Asphaltic Hydrocarbons in Petroleum' By Charles F. Mabery C A S E SCHOOL O F
APPLIEDSCIENCE,
CLEVWLAND, OHIO
ALTHOUGH
from the Appalachian oils, This work. is a study of the hydrocarbons in petroleum which the solid residue was distime hasbeendevoted much cannot be distilled without decomposition. The method used f o r solved in ether to a dilute in this laboratory to their separation was fractional solution in a hot mixture of ether solution, alcohol added until the composition of the disand alcohol, after first distilling the crude oil to 300" C.. first septhe paraffin began to partictillable hydrocarbons in arating the homologs of each series and then dividing the series into ipate flocculent, the solution petroleum, no attention has fractions. Identification of the hydrocarbons was then accomplished cooled to 0" C., filtered cold, hitherto been given here and by determination of specific gravity, molecular weight, and percentage again cooled to -20' C., little elsewhere to the idencomposition. and again filtered, with very tification of the hydrocarThis method of separation and analysis was applied to five little paraffin remaining in bons that cannot be distilled crude oils, f r o m West Virginia, Pennsylvania, Ohio, Texas, and the oil after the first filtrawithout decomposition. Of Russia. The Ohio oil being one of peculiar composition, a study tion. There is some diffithe f e w .attempts to sepaof its distillable constituents as well as of its fractions separated culty in reaching the point rate these constituents of by solution is given. The homologs of the heavier series above 300" C. where flocculent precipitapetroleum by cold solution vacuum appear to increase regularly and are divided into ( 1 ) the D tion begins without carryand i precipitation, "cold hydrocarbons, lubricants to the final heavy ends, and ( 2 ) the H ing down a large amount fractionation," the most group, asphaltic i n tbe heauy ends. A comparison of the various of the semisolidified oil, noteworthy is the work of oils shows a well-defined distinction between the lubricant and the HOMOLOG SEPARATIONCharitschoff, who described asphaltic hydrocarbons, and the higher specific gravity of the Texas In lots of 1000 to 1500 the following hydrocarbons and Russian lubricant hydrocarbons is due to their inherent strucgrams the vacuum residue, with their specific gravture. The wide variation in specific gravity of individual fractions free from paraffin, was ity: C19H38, 0.8930; C~&O, of the heavy crudes indicates the presence of carboxyl acids or esters. heated to the boiling point 0.9050; CzzHa, 0.9080; Iodine number determinations show that only the ring f o r m of unof the solvent in flat, corkC24H.16, 0.9130; C35Hm1 saturation applies to the lubricant hydrocarbons, and they do not stoppered bottles in a hot 0.9150; and it has doubtappear to enter into the formalite reaction as applied by the Marwater bath with frequent less suggested the frequent cusson method. shaking, t h e stopper being allusions to the presence of held in with the finger and naDhthene lubricants in G e r i c a n petroleum. However, none of the hydrocarbons frequently removed to relieve excessive pressure. For colfrom Baku oil, described in this paper, contain the series lection of the homologs of all the series intotenor fifteengroups, CnH2n,nor the CnHzn--2, although some of these specific gravi- the hot solution was poured off from each extraction and the ties are about the same as those of the series C,Hz,-8 in solvent distilled, the first fractions containing the more soluble Baku oil, to be described later, and none of the varieties upper end, and the diminishing solubility giving the consecutive fractions down to thelast residue. For further separation ofkAmericanpetroleum have shown such composition. Since petroleum hydrocarbons begin to decompose in dis- of the series homologs, t h e lowest group was first heated with tillation a t about 200" c.,and above 300' c. most crude oils, the solvent of proper concentration, sufficient to dissolve a even under pressures reduced to 20 mm., show evidence of considerable part, and the hot solution poured off, cooled, decomposition, it is impossible to separate the constituents of and again poured off from the separated oil. To this was petroloum by any form of distillation that will not distil a t added the next fraction, which was again heated, and the solution poured off for the treatment of the next fraction. 300" C. vacuum. This procedure was continued to the upper end. The solSEPARATION BY FRACTIONAL SOLUTION vent distilled off from the last treatment gave the first With the exclusion of distillation the only remaining possi- member of the group, and this procedure was repeated six bility appeared to be fractional solution, and, in view of the times. Since the specific gravities of the fifth andsixth variations in other physical constants, there seemed to be no fractions were approximately the same, it was assumed that reason why the different series and homologs should not the homologs of all the series were fairly well collected within possess sufficient differences in solubility to permit their the respective groups. The efficiency of this method appeared approximate separation in this manner. Trial of the various in the differences in consistency between the lowest fracsolvents excluded all but a mixture of ether and ethyl alcohol, tions, extremely thick, viscous, or nearly solid lubricants, and since all the constituents of petroleum dissolve freely as in the Appalachian oils, or thick, black, tarry or solid asin ether, but are quite insoluble in alcohol, it seemed possible phalts, as in the Texas and Russian oils, and the upper to prepare from them a convenient solvent. For general fractions, thin, amber-colored lubricants. use a mixture of equal parts by volume, with suitable variaSERIESSBPARATION-Beginning a t the lower end of the tions for the more soluble lighter ends, and the less soluble group each fraction was about half dissolved in rich, hot constihents of the heavier ends proved efficient for all the solvent, decanted, leaving a residual oil, H , the solvent disvarietEes of crude oil. For convenience of reference, the tilled, giving another residual oil, D, and this was continued lighter. fractions will be referred to as the "higher" or "upper with all the fractions to the upper end. To be sure that a ends," and tthe heavier as the "lower ends" of the series or single extraction gave an approximate separation, it was group. followed by another similar treatment, giving two series, Da Under a pressure of 30 mm. the crude oil was first distilled and Dh. The specific gravities of a and h proved to be suffito 300" C. For the removal of the paraffin hydrocarbons ciently concordant to indicate a fairly satisfactory separation by the first treatment. a Received December 4, 1922. ~
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
1234
I n a second mode of series separation each of the first group fractions was heated to boiling with the solvent, the hot solution decanted, cooled, again poured off from the separated oil and distilled, giving three oils-H, the first residue; C, the residue from cooling; and D, the residue from the distilled solvent. Each of these oils was again treated in a similar manner, and this treatment continued three or four times, thus dividing the original oils into eight or twelve fractions, did not materially change the specific gravity from the results of a single cross separation, from which it was inferred that the marked difference in solubility gave a fairly good separation in the first extraction. The following examples of its application on some of the oils as a means of control show the rapid separation by this method. A top fraction of a Russian vacuum residue containing more soluble, heavier carboxyl constituents brought up from below, and another from the Rosenbury oil, were separated by a single extraction into light and heavier constituents, as follows: Russian fraction, specific gravity 0.9236 Rosenbury (Pa ) specific gravity 0.90i-i
1'
0.9594 H residue hot 0.9198 C residue'solvcnt cooled 0.8925' D residue: solvent distilled 0.9230' H 0.8908' C 0.8875:D
No doubt the petroleum hydrocarbons under the condition of cold solution used by Charitschoff do exert a mutual solubility and interfere with the use of specific gravity as means of identification, but under the influence of a hot solvent it seems to be quite otherwise. The constants relied upon for grouping and identification were specific gravity, molecular weight, and composition by analysis. Determinations of specific gravity, except of the most viscous tars, which were weighed under water by the method of Kirschbraun, were made in a Sprengel pycnometer a t 20" C. In the beginning, molecular weights, especially of the heavy hydrocarbons, gave much trouble. Of the common solvents benzene alone a t the boiling point was applicable, and this was reliable only with the lower members of the Appalachian oils. Stearic acid a t 50" C. proved to be more satisfactory. A weight of oil from 0.3 to 1.5 grams, depending upon the specific gravity of the oil, gave a depression of from 0.150 t o 0.400" C. on the Beckman scale. The limitations of the method and the accuracy required for concordant readings are shown by the fact that for molecular weights above 1000, a depression of 0.001 " C. corresponds to nearly a difference of the increment, CH2,but below 500 to a difference of only 2 to 4 units. Occasionally, stearic acid gives abnormally high readings, doubtless caused by irregularity in the initial separation of crystals, which resisted all attempts toward correction by variation in stirring or other manipulation; but several, usually not more than three repetitions, readily revealed by concordant values, could be relied upon for the desired results. I n the extremely high values, 1600 or more, that define the hydrocarbons with the largest molecular weights, the observations were as closely concordant as with the oils having a molecular weight of 300. The commercial acid dried a t 100" C. is sufficiently pure; different lots showed small variations in the constant-for example, (1) 4.431, (2) 4.467; Bernstein gives for this constant, 4.5. Particular attention was necessary in getting complete solution of the heavy oils, and these required large weights for sufficient depression. T o yield the small differences in percentages of carbon and hydrogen necessary to distinguish between the different series, the gases from the asphaltic oils require the highest temperature for complete combustion that the most infusible glass will stand with a stream of oxygen on the copper oxide in front of the oil. Much time was saved by weighing the bulbs filled with oxygen. Although a 50 per cent solution of potassium hydroxide was used, with solid potassium hydrox-
Vol. 15, No. 12
ide or soda lime and phosphorous pentoxide in the safety tube of the Geissler bulb, a horizontal tube in front with soda lime and phosphorous pentoxide invariably showed from 0.0005 to 0.0020 gram increase in weight, sufficient, if lost, to spoil the analysis.
VARIETIESOF PETROLEUM INVESTIQATED General application of the method herein described to the petroleum fields of the world should doubtless involve the study of more than one hundred representativc varieties. I n this paper is included the separation of the constituent hydrocarbons from the following five typical crude oils: TABLE I
Cabin Creek, W. Va. 1st sample 2nd sample Rosenbury, Emblenton, Pa. Mecca, Ohio Sour Lake, Texas Baku, Russfa
Lowest Berea grit Rosenburysand Loose sand Loose sand Loose sand
1700 0.8100 1700 0.7850 1240 150 2000 Shallow
0.5080 0.9023 0.9333 0.8650
25 20
8683 8638
35 80
8852 9076 9580 9270
40
35
The Cabin Creek and Rosenbury oils are regarded as the best varieties of Appalachian petroleum, and known in the trade as paraffin-base oils. They contain large proportions of the gasoline, kerosene, and solid paraffin hydrocarbons, leaving residues solid wit& paraffin at 300" C., 30 mm. Authentic specimens of these oils, pale yellow in color, were procured for this examination from 0. C. Dunn, Marietta, Ohio. The Sour Lake oil, procured from a reliable source, is a typical heavy Southern crude, containing no CnHm + 2 hydrocarbons; the crystalline hydrocarbons occasionally observed in some distillates are probably of a heavier series. That the less volatile portions of the Texas oils are composed to a large extent of the best lubricant hydrocarbons cannot be doubted, and while the balance of the Northern crudes are of the lighter series, a large proportion in the basic Southern crudes are of the so-called asphaltic hydrocarbons which impart high viscosity to the lubricants containing them. How far the higher specific gravity and viscosity indicate superior lubricant quality depends, of course, on the inherent wearing quality of the asphaltic hydrocarbons, and this has never been precisely defined. I n the early development of Texas oil territory it was the synonym for high sulfur petroleum. Intimately associated with beds of sulfur, the sulfur was dissolved to the limit of saturation, and the resulting chemical changes eliminated hydrogen as hydrogen sulfide with the formation of the heavy hydrocarbons. I n the formation of such heavy crudes as the Sour Lake, evidently sulfur has been B determining element. With continued production the original proportions of sulfur in these oils, 1 to 3 per cent, have been greatly reduced. The Russian oil is a part of two barrels brought for the author's use twenty-five years ago from Baku. It is less stable than American oils and care is necessary to avoid decomposition, even under reduced pressure. Like all Russian crudes, the distillable portion is composed of the naphthene hydrocarbons that make superior luminants, and the remainder has a smaller proportion of lubricants than American petroleum, but considerable asphaltic constituents. The great body of the midcontinental fields yields oils with mixed Constituents; they are usually referred to as oils with a mixed base, paraffin and asphaltic, and the lubricants made Jrom them possess a peculiar composition and quality quite different from those of the Appalachian or the Southern crudes. From the general composition of these varieties of petroleum,
INDUXTRIAL A N D ENGINEERING CHEMISTRY
December, 1923
Fraction
c.
120-121 130-131 138-141 160-152 168-170 182-184 194-196 213-214 237-238 244-246
Specific Gravity 0.8600 0.8631 0.8648 0.8692 0.8696 0.8722 0.8730 0.8750 0.8834 0.8840 0.8837 0.8847
TABLE 11-DISTILLABLECONSTITUENTS O F MECCAPSTROLEUM -RBQU_IRSD---DBTERMINATIONSc C H Hydrocarbon Mol. Wt. % Mol. Wt. % % 86.66 180 86.61 13.26 177 86.60 194 86.67 13.23 190 208 86.54 86.62 13.33 204 87.28 220 12.75 87.10 21s 234 87.18 12.85 86.87 226 248 87.10 87.08 12.82 244 87.03 262 86.95 13.12 258 86.96 276 86.90 12.95 270 332 86.75 86.65 13.24 334 346 86.70 86.73 13.21 348 Light Hydrocarbcm s jrom Mecca Vacuum Residue 348 86.70 ClkH4e 343 86.62 13.25 388 86.60 CzaHrz 389 86.70 13.25
1235 -
n %
,
13.34 13.40 13.46 12.72 12.82 12.90 12.97 13.04 13.25 13.30
Series CnHzn-2 CnHzn- 2 CnHzn-2 CnHzn-4 CnHzn-4 CnHan-i CnHPn-4 CnHzn-r CnHzn-4 CnHzn-4
13.30 13.40
CnHm-r CnHzn-i
Refractive Index 1.4605 1.4625 1,4650 1.4665 1.4715 1.4710 1.4726 1.4750 1,4785 1.4815
paraffin hydrocarbons; the series CnHzs - 2, the light lubricants, especially of Appalachian petroleum; the series C.HZn-4 and CnH2,- 8, the heavier lubricants, the aromatic derivatives of benzene; and heavier series still poorer in hydrogen to C n H P r - 20 t,han appear in this paper are reported as present in European petroleum. The homologs of the heavier series above 300' C. vacuo appear to increase in regular increments similar to the distillable seriesthe D hydrocarbons, lubricants to the final heavy ends, except in the asphaltic crudes, and the H hydrocarbons, asphaltic in the heavy ends-in all except the Appalachian petroleum. I n the upper ends of the series first separated of all the oils DISTILLABLE CONSTITUENTS OF MECCA PETROLEUM examined, the specific gravity of the fractions increased very materially, some even higher than those of the lower ends. On account of its peculiar composition, and since there is This was found to be caused by carboxylic acids or ethers an opportunity, for the first time, to give a description of the more soluble than the hydrocarbons themselves. By further undecomposed hydrocarbons in a crude oil from beginning treatment of the upper fractions, the soluble oils were reto end, it seemed of interest to make the separation of Mecca moved, leaving the hydrocarbons in Table 111. The first oil complete from the first distillate. The lower constituents ten to fifteen D and H homologs separated in each crude oil were, therefore, separated by several distillations i n VUCUO, were given two or more extractions and collected in the refined, and the values obtained for specific gravity, molec- smaller groups presented in this table. Much time was lost in ular weight, and percentage composition are given in Table this work before it was learned that the crude oils contained 11. The peculiar disagreeable odor of some of the distillates more than one series of lubricants, and that the series as well indicates that the crude oil is not so far removed from its as the individual homologs differed materially in solubility. original organic source as the Appalachian oils. While the formulas and series represent the definite compoThese determinations of refractive index increase with sition of the fractions separated, it should require the manipincrease in specific gravity and in molecular weight the op- ulation of much larger quantities of the crude oils thanis posite of the hydrocarbons in the Appalachian oils, and, as possible in the ordinary chemical laboratory, and, as in fracwill appear later, even in the Mecca hydrocarbons of higher tional distillation, a greatly prolonged treatment to isolate molecular weight in the vacuum residue. The distillate with closer approximation the individual hydrocarbons. 244' to 246' C., specific gravity 0.8840, treated as in the To avoid serious loss in watch-glass transference, the fractions separation of the D and H series, gave a D hydrocarbon, were kept in bottles saturated with the solvent and small lots specific gravity 0.8850, refractive index 1.4865; and an H hy- were dried a t 120 O C. for examination. drocai*bon, specific gravity 0.8835, a lower refractive index, For the purpose of showing a t a glance the consistency of 1.4765, both indicating more than one series, as in the higher the hydrocarbons described in the preceding table as they hydrocarbons. Some of the Mecca vacuum residue that can appear spread out on watch glasses, in Table I V is given a be distilled a t 300' to 320 C. without decomposition, and brief description of the first and last members of each series that has been refined for use as a lubricant on fine watch and from all the crude oils. clock bearings, was separated by the solvent into the following In the destructive distillation of Appalachian petroleum fractions: by the common method of refining, the most valuable lubriSpecific Index of cants of the heavy ends, such as the last D and H fractions in Fraction Gravity Refraction the Cabin Creek, Rosenbury, and Mecca (Table 111), the best 1.4835 The molecular weight and analysis gave 1-0 0.8837 1.4805 the following formulas for the D group, 1-H 0.8780 lubricants in any petroleum, are lost in coking. This is of 1.4815 indicating the series CnHzn-i: 2-0 0.8789 less consequence in the asphaltic oils, for the lubricants in 2-H 0.8710 1.4765 CziHaa 3-0 0.8705 1.4815 CZZH40 these crudes are for the most part carried over in the steam 3-H 0.8682 1.4755 Ci4H44 4-0 0.8745 1.4785 CzrH4s distillates, leaving only asphaltic residues. 4- H 0.8680 1.4760 CisHrx 5-0 0.8750 .... On account of the less solubiliky of the lower members of , each series and the separation of homologs in only one direcThese hydrocarbons form the connecting link in the series tion, it was possible to remove very completely the higher between those that can and those that cannot be distilled. homologs, and, therefore, to obtain data for the calculation The data of this examination indicate more than one series. of the formulas of the lowest residual hydrocarbons as reS ~ R I EAKD B HOMOLOQ HYDROCARBONS IN PETROLEUM liable as the methods of definition are capable of yielding. These last hydrocarbons were, therefore, carefully purified for Investigations carried on in this laboratory and elsewhere the comparison of physical properties and lubricant value. have shown that petroleum is chiefly composed in variable Those from the heavier oils have the intensified qualities of proportions of the series CnHzn + f, gasoline, kerosene, and the commercial asphalts; black in color, they may be drawn
they seemed especially well adapted for this investigation, as representing the principal fields. Mecca petroleum, specific gravity 0.9023, known as a natural lubricant since the beginning of the petroleum industry, is typical of occasionally occurring small pockets or sections a t shallow depths where the original oil has been partially refined by natural agencies, leaving only hydrocarbons with large molecular weights, containing no gasoline, kerosene, or paraffin hydrocarbons and a very small amount of the asphaltic hydrocarbons, All but 12 per cent of the lighter end form the best lubricants.
O
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
1236 _ .
SPECIFIC FRACTION GRAVITY Mol. Wt.
D Series 1 2 3 4 5 6 7 8 H Series 1 2 3 4 5 6 7
D Series 2 3 4 Series
1 2 3 4 5 6 7 8 9
DETE_RMINED-----
c
TABLE111
Per cent
H Per cent
1
5 6
7
D Series 1 2 3 4 5 H Series 1 2 3 4 5 6
7 8
CALCULATED--C H Per cent Per cent
r-__
FORMULA Mol. Wt. Cabin Creek
SERIES
REIIRACTIVB INDEX
0.8755 0.8764 0.8815 0.8882 0.8829 0.8832 0,8835 0.8855
309 327 428 452 488 585 717 803
86.76 86.76 86.56 86.45 86.32 86.35 86.10 86.27
13.21 13.18 13.34 13.44 13.48 13.59 13.79 13.73
C22H4O C24H44 CaiHss C83H62 CssHe6 CaHso CszHioo CS3H112
304 332 430 458 486 584 724 808
86.84 86.75 86.50 86.46 86.42 86.30 86.20 86.14
13.16 13.25 13.50 13.54 13.58 13.70 13.80 13.86
CnHzn-4 CnHzn-4 CnHzn-4 CnHan-4 CnHzn-4 CnHzn-4 CnHzn-4 CnHzn-4
0.8721 0.8725 0.8729 0,8819 0.8863 0,8873 0,9063
459 476 490 635 760 769 1696
87.21 87.20 87.02 86.52 86.72 86.72 86.50
12.70 12.64 12.86 13.51 13.22 13.42 13.43
CaaHsa 454 CS4H60 468 C36H64 496 C46H8P 636 64H100 748 CasHioa 762 CizzHzsa 1700 Rosenbury
87.22 87.20 87.10 86.79 86.64 86.60 86.32
12.78 12.80 12.90 13.21 13.36 13.40 13.68
CnHzn- a CnHzn- I CnHzn-a CnHzn- 8 CnHzn- a CnHzn- s CnHzn-la
0.8796 0.8816 0.8822 0.8836
384 438 481 518
86.13 86.68 86.42 86.15
13.40 13.24 13.39 13.71
CzaHsn C8ZH60 C3SH66 Cs7H7o
388 444 486 514
86.60 86.48 86.42 86.38
13.40 13.52 13.58 13.62
CnHzn- a CnHzn- a CnHnn- 8 CnHzn- a
1.4930 1.4890
0.8742 0.876.5 0.8812 0,8850 0.8848 0.8865 0.8950 0,8998 0.9079
549 6i5 639 666 727 805 830 980 1730
87.08 86.78 86.65 86.60 86.59 86.63 86.49 86.69 86.58
12.85 13.16 13.25 13.30 13.29 13.37 13.52 13.28 13.35
552 622 636 664 720 804 832 954 1734
86.96 86.82 86.78 86.74 86.68 86.56 86.54 86.80 86.50
13.04 13,18 13.22 13.26 13.32 13.44 13 46 13.20 13.50
CnHzn-a CnHzn- s CnHzn- a CnHzn-a CnHzn- s CnHzn- s CnHzn- II CnHzn-iz CnHzn- 16
1.4920
I
1.4920
.... .... .... .... ....
1.4880 1.4810 1.4880
.... .... ....
1.4870
....
1.4810
....
1.4880
.... .... .... .... 1.4870 .... .... 1.4870
Mecca
D Series 2 3 4 5 6 7 8 H Series 1 2 3 4
Vol. 15, No. 12
.... .... .... .... .... .... .... .... .... .... ....
0.8945 0.8950 0.8960 0.8962 0,8966 0.8982 0,.8998 0.9171
465 500 631 662 728 770 832 1080
87.37 87.13 86.87 86.60 86.62 86.41 86.45 86.68
12.61 12.70 13.10 13.20 13.22 13.50 13.47 13.42
468 496 636 664 734 776 832 1084
87.20 87.10 86.78 86.75 86.66 86.60 86.54 86.34
12.80 12.90 13.22 13.25 13.34 13.40 13.46 13.66
CnHm- 8 CnHzn- a CnHzn- 8 CnHzn- s CnHzn- s CnHzn-s CnHzn- a CnHzn- a
0.9058 0.9072 0.9018 0 .9022 0.9052 0.9065 0.9600
477 550 684 725 823 992 1662
87.65 87,57 87.06 87.16 87.12 87.22 87.34
12.37 12.48 12.82 12.76 12.73 12.75 12.56
478 548 688 688 828 992 1668 Sour Lake, Texas
87.87 87.59 87.21 87.16 86.96 87.10 87.23
12.13 12.41 12.79 12.76 13.04 12.90 12.77
CnHzn-12 CnHzn-iz CnHzn-iz CnHzn-a CnHzn- 12 CnHzn-la CnHzn-zo
0.9408 0.9467 0.9482 0.9535 0.9595 0.9643
450 462 503 531 554 849
87.93 88,09 87.82 87.58 87.62 86.80
11.91 11.81 12.15 12.30 13.32 13.18
450 464 506 534 562 856
88.00 87.93 87.74 87.64 87.54 86.92
12.08 12.07 12.26 12.36 12.46 13.08
CnHzn- 12 CnHzn-in CnHm-la CnHzn-ia CnHzn-12 CnHm-iz
1.4980
0.9470 0.9497 0.9559 0.9643 0.9700 0.9714 0.9720 1.0230
602 630 680 716 792 854 981 1239
87.90 87.60 87.55 87.58 87.66 87.50 87.65 87.60
12.05 12.45 12.35 12.25 12 25 12.24 12.35 12.27
600 632 684 712 785 848 988 1240 Baku, Russia
88.12 87.62 87.72 87.64 87.88 87.74 87.45 87.98
12.00 12.38 12.28 12.36 12.12 12.26 12.55 12.02
CnHzn-is CnHan-16 CnHzn-16 CnHan-1s CnHzn-zo CnHzn-zo CnHzn-no CnHan-80
1.4970
0,9186 0.9251 0,9254 0.9262 0.9288
381 402 494 640 1022
87.42 87.75 87.46 86.91 87.29
12.53 11.93 12.53 13.03 12.68
308 396 494 634 1026
88.05 87.88 87.47 87.06 86.55
11.95 12.12 12.53 12.94 13.45
CnHzn-lo CnHzn-io CnHzn-io CnHzn-io CnHzn-io
1.4920
0.9025 0.9160 0.9167 0.9150 0.9162 0,9242 0.9360 0.9402
300 334 378 420 460 661 847 1098
87.95 87.98 87.36 87.28 87.29 86.72 86.63 98.31
11.96 12.01 12.53 12.60 12.66 13.21 13.30 12.68
300 328 384 426 454 664 846 1100
88.00 87.80 87.50 87.32 87.22 86.75 86.52 87.28
12.00 12.20 12.50 12.68 12.78 13.25 13.48 12,72
CnHzn- s CnHzn-a CnHzn- s CnHzn- a CnHzn- s CnHzn- s CnHzn- 8 CnHm-zo
,...
I
out to a considerable length in very fine threads, and possess great adhesiveness. The residual lubricants from the Appalachian crudes, amber in color, greasy in feel, and of high viscosity, differ in appearance from the gray basic stocks of the midcontinental lubricants, which are doubtless to some extent mixtures with asphaltic bases. On account of the limits of accuracy in the determinations of molecular weights mentioned above, the fractions with higher values, such as the Rosenbury fraction CI25H2$4,may be incorrect by one or more increments CH2, but by the determinations upon which it is based it must have a high value, for the fraction 9-H, specific gravity 0.8933, gave in two
.... .... .... .... ....
1.4960
....
1.4940
..
.... ....
1,4940
....
.... .... .... ....
.. . .... .... .... .... ....
1,4910
molecular weight determinations (1) 1722, (2) 1718; further fractioned with specific gravity 0.8943 it gave 1728; and still further fractioned with specific gravity 0.9079 it gave 1730. There appears, therefore, to be no doubt as to its high molecular composition. So d s o the molecular weight 1696 of the Cabin Creek 7-27 fraction, specific gravity 0.9063, with the next largest value, appears t o be correct, since it was separated from both specimens of the crude oil which gave fractions with the molecular weights (1) 1685, (2) 1690, and with analysis corresponding to the formula C123H232. Therefore, with methane as the first gaseous hydrocarbon and pentane as the first liquid, under ordinary pressure, passing
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
December, 1923
TABLEIV-CONSISTENCY CABINCREEK
ROSENBURY
OF
D
AND
1237
H HYDROCARBONS
SOUR LAKS
MECCA
R ussIA N
D Series
(1) Ligh?amber;fine,light
(1) Light amber: light lubricant
(8) Dark.
flows lubri-
(8) Dark amber: thick flow; heavy lubricant
(1) Light amber; like 1-D
(1) Thin flow; light lubri-
( 8 ) Dark amber;
(8) Dark amber: slow flow
lubricant
amber; readily; heavy cant
solid
thick,
fine
cant
amber: just good lubricant
(1) Dark amber: slow flow; good lubricant
( 7 ) Dark amber: thick flow: heavy lubricant
(7) Black, sticky t a r ; no lubricant
(8) Black, sticky, asphalt, oil; no lubricant
H Series (1) Light amber; thicker than Cabin Creek and Rcsenbury (7) Black, sticky, tarry oil
(1) Dark amber: just flows; good lubricant
(1) Dark amber:
(1) Light amber; lubricant
through the several series of light and heavy liquids, through viscous lubricants and solid paraffin, the final lower end is reached in these oils, so viscous they will not flow a t common temperatures, the heaviest lubricant hydrocarbons in Appalachian petroleum. Although the Mecca H group is composed in general of much heavier hydrocarbons than those from the Appalachian oils, the lubricants in the lower end of its series are not very different from the others. The last H hydrocarbon, ClzzHz~, specific gravity 0.9600, is not a lubricant but an asphalt. The last D hydrocarbon, Cr8H148, specific gravity 0.9171, is a true lubricant, viscosity 5461 seconds; and the last Rosenbury, 9-H, specific gravity 0.9079, viscosity 5248 seconds, water standard 2.4 seconds a t 50' C., probably the highest viscosity of any petroleum hydrocarbons, not only indicates that lower specific gravity is characteristic of the best lubricants, but it defines the difference in lubricant quality between the hydrocarbons of the Appalachian and those of the heavy asphaltic crude oils, with the higher specific gravity of the latter. Furthermore, this Mecca asphaltic oil, 7-H, has nearly the same high specific gravity, 0.9600, as the Sour Lake D asphaltic oil, specific gravity 0.9643, which resembles all the others with which it is associated, except the higher homologs, which are lubricants. The last Sour Lake oil, &H, specific gravity 1.0230, C ~ O H Iis~ O a ,brittle asphalt, for which no lubricant quality can be claimed. The predominating asphaltic nature of the Baku oil is equall-ywell defined, although with smaller values in specific gravity than the Sour Lake. The last H hydrocarbon is a black, sticky asphalt, a little higher in viscosity than the Sour Lake, but the last 5-D, C74H138, also a black sticky oil, has a higher viscosity than any other in this or the Sour Lake groups. I n the Baku oil, unlike the others, the D series, CnHzn-lo, seems to be poorer in hydrogen and heavier t h m the I-I series. The latter appears to be composed of a large number of low molecular weight hydrocarbons, the upper lubricants, the lower asphalts. As in the Sour Lake oil, the asphaltic hydrocarbons, in part lubricants, appear to predominate; even the last D oils are asphaltic. The halogens react with these hydrocarbons as readily as with those of lower molecular weights, and with the same brisk evolution of the haloid acid. At about 70" C. the action proceeds most satisfactorily, with complete solution of the oil in 4 or 5 hours. At higher temperatures complete solution may take place in 1 hour. There is a marked difference in the appearance of the products from the D and H hydrocarbons. On pouring into a large volume of water, all the nitro derivatives from the D hydrocarbons separate in a flocculent, finally crystalline form, those from the heavy H hydrocarbons, as sticky oils. The reactions of these bodies show them to be nitrocarboxylic acids. With the ammonium salt formed by solution in ammonium hydroxide silver nitrate precipitates the silver salt readily soluble in nitric acid. With tin and hydrochloric acid the nitro compound i x reduced to the amino acid. Barium and lead salts are
(1) Dark
fine
flows;
( 8 ) Black, brittle, asphalt
thick flow; heavy lubricant
solid
Thick, black asphalt 011
readily formed. Analysis showed a much lower molecular weight than that of the original oil. While the action of solvents indicated complex mixtures, it seemed possible by proper fractionation to separate individual constituents. A study of these derivatives will be continued. A summation of the facts relating to the nature of these hydrocarbons that make up from 25 to 35 per cent of petroleum seems to present a well-defined distinction between the lubricant and the asphaltic hydrocarbons, and appears to support the view that the higher specific gravity of the Sour Lake and Russian lubricant hydrocarbons is due to their inherent structure, which is altogether different from the lubricant structure of the Appalachian oils. I n further study now in progress of petroleum lubricants in general, including the midcontinental oils, the relation of high specific gravity and viscosity to wearing quality will receive attention. SULFURIS SOURLAKE,RCSSIAN,AND APPALACHIAN HYDROCARBONS
All determinations of sulfur were made by combustion in oxygen, the most accurate and expeditious method for sulfur in oils, tars, and asphalts. The variation in the percentage of sulfur indicates that the solvent differentiates in the sulfur derivatives as in that of the hydrocarbons, the greater part appearing in the H series. TABLEV-PER
Sour Lake Cabin Creek Rosenbury Mecca Russian
CENT
SULFURI N HYDROCARBONS
D FRACTIONS 1 3 6 0 33 0 27 0 57
H FRACTIONS Crude Per cent Oil 1 4 8 0 48 0 66 0.59 0 05 0 01 0 08 0 15
0 67
CARBOXYL DERIVATIVES IN AMERICAN PETROLEUM
All previous records of individual fractions from the different varieties of heavy petroleum-Ohio, California, Texas, Russia, etc.-have shown wide variation and abnormally high values in specific gravity. So the different series from the heavy crudes described in this paper show similar variations. These observations indicate that the carboxyl acids, or more probably esters, are present in all varieties of American petroleum, but in variable amounts, from the traces detected in the Appalachian oils to 2 per cent indicated by combustions of the fractions in the Sour Lake asphaltic oil. I n further testing for the presence of carboxylic acids, the upper D Sour Lake fractions, dissolved in ether and extracted with potassium hydroxide, the aqueous solution acidified and again extracted with ether, leaves on evaporation a considerable amount of the oily acid residue. The specific gravity of the hydrocarbon oil before and after the extraction of 4-0 fraction was, respectively, 0.9642 and 0.9575. The action of the solvent in carrying up the carboxyl derivatives in the fractions of the Russian oil is plainly evident in the high specific gravity, 1.1050, of the oil extracted from the upper D fraction, and the composition of this fraction (C, 86.83; H, 10.41) as
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Vol. 15, No. 12
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
compared with a fraction in the middle of the series (C, 87.58;
H, 12.45), viscosity of the first oil a t 50" C. 317 seconds and of the second oil 2005 seconds, water equivalent 2.8 seconds. The carboxyl oil dissolved out from Mecca 1-D fraction, specific gravity 1.0105, gave by combustion 86.70 per cent C, and 12.41 per cent H, with a difference of 0.89 per cent for 0 2 . The viscosity of this oil was 468 seconds as compared with the hydrocarbon C120H220,specific gravity 0.9171 a t the lower end of the same series, viscosity 1073 seconds a t 50" C., water equivalent 2.8 seconds. It would be of interest to isolate larger quantities of these oils and ascertain their composition. UNSATURATION AS SnowN BY IODINE NUMBERS Of the two forms of unsaturation, open chain and the ring, evidently only the latter applies to the lubricant hydrocarbons and it has received much attention with respect to this condition as shown by the iodine numbers. Iodine reacts indiscriminately on the D and H hydrocarbons without showing any consistent relation or differences, but with results much like those observed in distillates. Trial of the Johansen method that appears to reveal what has been regarded as
addition is really substitution, not only disproved addition, but gave negative numbers to the extent of two to four units.
FORMALITE REACTION The D hydrocarbons described in this paper do not enter into this reaction as applied by the Marcusson method frequently quoted in works on lubrication, and the H hydrocarbons of the Texas and Russian oils give variable mixtures with an indefinite composition. The Rosenbury fraction 3-H, specific gravity 0.8512, gave after the reaction, 0.8827; and the Russian fraction 4-0, specific gravity 0.9262, after the reaction, 0.9291. I n no case cou€d the reaction proceed unless the resulting increase in temperature was unchecked. No naphthene, C,Hh, lubricant hydrocarbons have appeared, and contrary to the statement of Marcusson, the hydrocarbons from American petroleum have shown a superiority in lubricant quality over those from the Russian oil.
Acx NOWLEDGME NT The writer wishes to acknowledge the efficient aid which he has received in this work from his assistants, R. C. Knapp and George Grossman.
T h e Value of Sweet Potato Flour in Bread-Making' By H.C. Gore
'
BUREAUOF CHEMISTRY,WASHINGTON, D. C.
I
T WAS recently shown2 that two widely grown commercial varieties of sweet potatoes, Nancy Hall and Porto Rico, are rich in diastase and that they retain their diastatic power when sliced, dried, and ground into flour. The diastatic power ranges from 200 to 500 Lintner. That in the southern sweet potato we have a source of diastase capable of competing with the cereal sources of this important enzyme is shown from a study of the economics of sweet potato production. The present cost of growing sweet potatoes on southern farms is shown by Haskel13to range from 22 cents per bushel upward, depending on the yields, the higher yields (160 bushels per acre) being produced a t the lower unit cost. Sweet potatoes are a sure crop, respond well to fertilizers, and their cultivation is well understood. The entire crop or any portion of it can be used as raw material for the production of sweet potato flour. I n a normal season about 40 per cent of the crop overgrows-that is, the roots become so large (greater than 3.5 inches in diameter) that they are not in demand for table use. They are, however, acceptable for technical uses. I n preparing sweet potato flour the process required is very simple. It is not necessary to peel the potatoes; they should, however, be washed in order to remove adhering soil. They are then sliced and dried. I n drying, an u p draft drier has been found to give satisfactory results. The temperature employed should not exceed 50" C. The yield is one-third the weight of the potatoes taken. Sweet potato flour imparts but little flavor to the mash. It does not liquefy starch so rapidly as barley malt. It has, however, much greater saccharifying power. Its uses in 1
Presented before the Division of Agricultural and Food Chemistry
at the 05th Meeting of the American Chemical Society, New Haven, Conn.,
April 2 t o 7, 1923. * J . B i d . Chem., 44, 19 (1920). 8 U. S. Deal. Agr., Bull. 648.
industry remain to be worked out. The most interesting development which has occurred thus far is the discovery of the fact that sweet potato flour can be used as a bread impr~ver.~ A large number of experiments were run in which a series of mixtures with varying percentages of sweet potato flour with hard wheat flour was tested. The different percentages of sweet potato flour used were based on the weight of flour taken. The baking tests were made by the straight dough method, with the following formula: GRAMS PER BATCH Flour Salt Sugar Yeast Water
460
7
16 10
Sufficient t o produce a dough of proper consistency
The sweet potato flour was mixed with the liquid ingredients before the wheat flour was added. Before panning, 170 grams of dough were removed for expansion tests, the remainder being panned for baking. It was found that a substantial increase in volume occurred when sweet potato flour was used. One and one-half per cent of sweet potato flour appeared to give the best results. I n one test, which may be considered as typical, the volume of the control loaf was 2250 cc., whereas that of the loaf prepared from the mixture containing 1.5 per cent sweet potato flour was 2425 cc. The texture of the bread and its color and flavor remained fully up to the standard. These results have been confirmed by independent tests made in three commercial baking laboratories. There is, therefore, no doubt of the fact that sweet potato flour does give a substantial increase in volume when used as a bread improver. 4 The baking tests herein reported were made by I,. H. Bailey, of the Bureau of Chemistry, and Miss R. Leone Rutledge, formerly of the Bureau of Chemistry.
