1062
INDUSTRIAL AND ENGINEERING CHEMISTRY
(5) Cabot, Godfrey L., Inc., Boston, Mass., “Carbon Black under the Electron Microscope.” (6) Carson, C. M., and Sebrell, L. B., IND.ENQ.CHEM.,21, 911 (1929). (7) Emmett, P. H.,Symposium on New Methods for Particle Size Determination in Subsieve Range, p. 95, Am. SOC. Testing Materials, March 4, 1941. (8) Glasstone, S., “Textbook of Physical Chemistry,” Macmillan, New York, 1951. (9) Hildebrand, J. H., Benex, H. H., and Mower, L. M., J. Am. Chem. Soc., 72, 1017 (1950). (10) Huttig, G. F.,Monatsh. Chem., 78, 177-84 (1948). (11) Jones, G., and Baeckstrom, S., J. Am. Chem. SOC.,56, 1517-24 (1934). (12) Jones, G.,and Kaplan, B. B., Ibid., 50, 1845 (1928).
Vol. 47, No. 5
(13) Kendall, C. E., Dunlop Research Centre, Birmingham, England. InternalReut.. C.R. 1103.1947. (14) Schaeffer,W.D.,Smith, W. R., and Polley, M. H., IND. ENQ. CHEM.,45, 1721 (1953). (16) Schoenfield, F. K., Zbid., 27,571 (1935). (16) Sips, R., J. Chem. Phys., 16,490 (1948). (17) Smith, W. R., Thornhill, F. S., and Bray. R. R.. IND.ENQ. CHEM..33. 1303 (1941). (18) Sweitzer, C. W., Venuto,‘L. J., and Estelow, R. K., Paint, Oil Chem. Rev., 115,22 (1952). (19) Walker, W .C.,and Zettlemoyer, A. C., J. Phys. 6 Colloid. Chem., 52,47-58 (1948). RECEIVED for review September 14, 1963.
ACCEPTEDNovember 22, 1954. Division of Rubber Chemistry, 124th Meeting, ACS, Chicago, Ill., September 1953.
Composition of Lubricating Oil
Portion of Petroleum BEVERIDGE J. MAIR AND FREDERICK D. ROSSINI Carnegie Institute of Technology, Pittsburgh, Pa.
I
N 1938, the American Petroleum Institute Research Project 6
reported the results of its extensive fractionation of t h e lubricant fraction of t h e project’s representative petroleum from the Ponca, Okla., field (6-9). T o obtain additional information concerning t h e composition of the lubricating oil portion of petroleum, the Advisory Committee for t h e project recommended t h a t a number of “homogeneous” fractions be selected from the lubricant portion of t h e project’s representative petroleum which had been subjected t o extensive fractionation, and that arrangements be made for a cooperative spectroscopic examination of these fractions by selected laboratories of the petroleum industry. This report gives a summary of the results obtained by the 15 laboratories cooperating with the API Research Project 6 in this work. COOPERATING LABORATORIES
Fourteen laboratories cooperated in the spectrographic work. Laboratory Atlantic Refining Co., Philadelphia, Pa. California Research Corp., Richmond, Calif. Gulf Research and Development Co., Pittsburgh, Pa. Humble Oil and Refining Co., Baytown, Tex. Phillips Petroleum Co., Bartlesville, Okla. Shell Oil Co., Houston, Tex. Sinclair Refining Co., Harvey, Ill. Socony-Vacuum Laboratories, Paulsboro, N. J. Standard Oil Co. (Indiana), Whiting, Ind. Standard Oil Development Co., Linden, N. J. Sun Oil Co., Marcus Hook, Pa. The Texas Co., Beacon, N. Y . Union Oil Co. of California, Brea, Calif. Universal Oil Products Co., Des Plaines, Ill.
Identifying Letter A B C D E F G H I J K L M N
T h e Standard Oil Co. of Ohio, Cleveland, Ohio, cooperated by performing a n experiment on the fractionation of one sample by thermal diffusion in t h e liquid phase. SAMPLES INVESTIGATED
Figures 1 t o 3 show schematically the procedures b y which the samples used in this work were produced from t h e original petrolym.
Figure 1 illustrates t h e scheme of separating the lubricant fraction into four broad portions. The entire material was dewaxed at -18’ C. with ethylene chloride t o produce a socalled “wax“ portion containing a considerable portion of clear oil. T h e remaining material was then subjected to extraction at about 40’ C. with liquid sulfur dioxide t o produce a Lisulfur dioxide extract.” T h e material insoluble in the sulfur dioxide was treated by adsorption with silica gel t o produce a “waterwhite oil” and a portion representing the “silica gel holdup.” T h e sulfur dioxide extract was brought into solution in liquid sulfur dioxide at -55” C., and extracted with petroleum ether at the same temperature t o produce a “petroleum ether-soluble” portion and a “residue” portion, t h e latter from the material remaining in t h e sulfur dioxide layer. T h e petroleum ethersoluble material was combined with t h e silica gel holdup t o make what may be called the “extract” portion of the lubricant fraction. I n this manner the original lubricant fraction was separated into t h e following four broad fractions: wax portion, 35%; residue portion, 8%; extract oil portion, 22%; and water-white oil portion, 35%. Figure 2 illustrates the manner in which the water-white oil portion was fractionated b y distillation and extraction, This material was first subjected to a systematic distillation in high vacuum in single stages, repeated about eight times, to produce a number of supposedly substantially constant-boiling fractions. These fractions were then subjected t o extraction with reflux in columns 46 feet long with acetone (plus some water for t h e more soluble fractions) as t h e solvent. Six series of fractions-A, B, C, D, E, and F, as shown in the lower part of Figure 2-were produced ( 4 , 6, 9). The approximate locations in t h e extraction process of samples 1, 2, 3, 4, 5, and 7 selected for spectrographic analysis are shown by the numbered blocks in the lower part of Figure 2. Actually, the production of t h e fractions comprising series A was more complicated than is indicated and involved division of t h e original charge into three portions, t h e separate extraction of each portion, and the blending of appropriate fractions t o produce three new charges, which were then extracted t o give the final fractions (6). Figure 3 illustrates the separation of t h e extract oil portion. This material was processed in the same manner as the waterwhite oil, except t h a t the extraction occurred in columns 55
1063
LUBRICANT FRACTION 100 % 16 Cuts, constituting 10%of original crude KV100.~~0.211 to 2 96
stokes
VI.75
I
DKK).F:087 to 0 91 g/ml
to 90
1-1
Dewoxing ot - 1 8 O c with ethylene chloride
Extraction at 40°C with sulfur dioxide
Trea t ment with silica gel
t
,
Extraction a t -58% with sulfur dioxide and petroleum ether
I "Petroleum ether solubleM
I I "Silica gel hold-up"
9%
II
"WAX" PORTION
35% Figure 1.
I I I
"RESIDUE" PORTION 8%
1 I
OIL PORTION
22 %
Schematic diagram of separation of lubricant fraction into four broad portions
feet long with methyl cyanide (plus some acetone for the less soluble fractions) as the solvent. The five series of fractions produced are shown in the lower part of the figure, and t h e position of sample 6 is indicated (6-9). Samples 1 to 7 are described in Table I. One of the fractions from the water-white oil portion, sample 7 , was subjected t o additional fractionation b y thermal diffusion in t h e liquid phase in a n experiment performed by the Standard Oil Co. of Ohio. T h e company reported: This experiment was performed in a concentric tube column, fabricated from stainless steel, 6 feet in length, having a n inner tube with outside diameter of 5 / 8 inch, and with a n annular space of 0.012 inch between t h e inner and outer tubes. T h e outer tube was electrically heated and the inner tube cooled with water. Ports located every 3.6 inches along t h e length permitted t h e collection of 20 separate fractions, each with a volume of approximately 1.45 ml. T h e entire amount of sample 7 available (13.5 ml., enough t o fill only 45% of t h e annular space) was charged
t o t h e apparatus, and t h e power input was adjusted so t h a t t h e hot wall temperature adjacent t o t h e empty portion was 160' F. and t h a t adjacent t o t h e sample was 110' F. T h e average temperature of t h e water used for cooling was 65' F., with a rise not greater than 10" F. between t h e bottom and top of t h e column. These conditions were maintained for a period of 6 weeks, after which t h e contents of t h e apparatus were removed as nine separate fractions, 7a t o 7i, each approximately 1.4 ml. in volume.
,4plot of refractive index with respect t o the fractions produced in the foregoing separation is shown in Figure 4. KINDS OF SPECTRAL EXAMINATIONS
The kinds of spectral examination made b y each laboratory are summarized in Table 11. Two laboratories obtained mass spectral data, 12 laboratories obtained infrared spectral data, and 12 laboratories obtained ultraviolet spectral data. Both of t h e laboratories obtaining mass spectral data interpreted their
Vol. 47, No. 5
INDUSTRIAL AND ENGINEERING CHEMISTRY
1064
Table 1. Description of Samples Examined Sample Average molecular formula Value of x in formula, CnHzn+ Boiling ,point, a t 1-mm. Hg pressure, O C. Refractive index, n,, a t 25' C. Density, d a t 25' g./ml. Kinematic 'viscosity,'ktokes At 100' F. At 210; F. Kinematic viscosity index Specific refraction, (l/d) (n,* l)/(nDz 2) Refractivity intercept, nD - (d/2) Specific dispersion, 104(n, - - np)/d Aniline point, C. Average molecular composition'" No. of cycloparaffin rings No. of aromatic rings Identification of sample in original report Fraction Series Reference a Plus paraffin side or connecting groups as appropriate.
-
+
2
3
Cz7.8Hss.e
CZ1.6H63.2
12%7 (0.832)
-2.0 (204) 1.4729 (0.861)
Czs.sH6r.e
-2.0 (222) 1.4713 (0.860)
-2.0 (249) 1,4730 (0.860)
-4.0 (204) 1.4836 (0.878)
0.1977 0.0410 137 (0.330) (1.045) (99) 112
0,3483 0.0526 90 (0.325) (1.043) (99) 106
0,3980 0.0589 99 (0.325) (1.041) (99) (111)
0.6318 0.0815 104 (0.326) (1.043) (99) (117)
0.6854 0,0695 39 (0,323) (1.045) (99) 100
1.46 0.0971 0 0.3242 1.0506 132 (46)
0.4195 0.0601 95 (0.326) (1.041) (99) (110)
1
2
2
2
3
2 or 3 1
2
1
0.0
results to give the percentages of the various types of hydrocarbons in the samples. Three of the laboratories obtaining infrared spectral data analyzed their results to give semiquantitative values for the number of various groups in the average molecule. Several other laboratories commented on the data and expressed their conclusions in qualitative terms. Detailed information regarding the spectroscopic procedures, calibrations, and methods of calculation used by the cooperating laboratories in obtaining the results reported here is available from the collaborating laboratories.
5
7
C27.7H61.4
CZB.SH67.6
(-2.1)
12%2 (0.862)
20
C
4
Table 11. Kinds of Examination Made by Each Laboratory Lab.
EXAMINATION O F WATER-WHITE OIL PORTION
Mass Spectral Examination. Two laboratories, A and F, obtained mass spectral data. Laboratory F, using the parent-peak portion of the spectrum, interpreted the data for samples I, 2, 3, 4,5, and 7 t o give the relative amount of each type of hydrocarbon for molecules of different numbers of carbon atoms per molecule, of each type of hydrocarbon in the total sample, and of the total sample constituted by molecules of different numbers of carbon atoms per molecule. Laboratory A interpreted the data for sample 1 in a similar manner. Table I11 gives the percentage of the total sample constituted by the components with different numbers of carbon atoms per molecule, while Table IV gives the percentage of each type of hydrocarbon in the total sample. The relative amounts of the types of hydrocarbons for the components with different numbers of carbon atoms are not given, since, within the accuracy of the determination, these are the same as for the total sample. A comparison of the results obtained by Laboratories A and F for sample 1 (see Table IV, columns 2 and 3 ) indicates reasonable agreement, the maximum difference (6 %) occurring with the monocycloparaffins. The manner in which the composition changes from the less soluble t o t h e more soluble fractions for series A may be noted by comparing the values for samples 1, 2, and 5. An estimate of t h e composition of the total material comprising series A, obtained principally by interpolation, b u t with a small extrapolation at both ends of the series, leads t o the following values for t h e several components, in percentage by volume: branched paraffins, 15 ; monocycloparaffins, 34; dicycloparaffins, 18; tricycloparaffins, 12; tetra- and higher cycloparaffins, 17; and aromatics, 4. Table V gives the results obtained by Laboratory F for the fractions produced by thermal diffusion, samples 7a t o 7i, inclusive, as well as a n average value for the total sample (obtained on t h e assumption t h a t the fractions were exactly equal in volume) and a value for the total sample obtained by direct determination. Examination of the spectral data showed that t h e process of thermal diffusion gave no detectable separation
4 C84.&6.8
Kind of Spectral Examination
Samples
A
LMMaSS
Ultraviolet, 2600 to 2900 A.
1, 2, 3, 4 , 5, 6 1, 5, 6
B
Infrared 1.5 to 25 microns Infrared' 2 to 15 microns Ultravidet, 2000 to 4000 A.
1, 2, 3.,4, 5 , 6 7a to 71 1, 2, 3, 4, 5, 6
C
Infrared 2 5 to 15 microns Ultravioiet: 2000 to 4000 A.
1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5 , 6
D
Infrared, 2 to 16 microns Ultraviolet, 2300 to 3600 A.
1 , 2, 3, 4, 5, 6, 7a to 7i 1, 2, 3, 4, 5,6
E
Infrared, 2 to 16 mirrons Ultraviolet, 2200 to 4000 A.
1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5 , 6
F
Mass
1, 2, 3, 4, 5, 6, 7, 7a to 7i
G
Infrared 2 to 15 microns Ultravioiet, 2200 to 4000
1, 2 , 3, 4, 5, 6 1, 2, 3, 4, 5, 6
H
Infrared, 3 t o 23 microns Ultraviolet, 2200 to 3800
1, 2, 3, 4, 5, 6 1, 2, 3
I
Infrared, 1 to 2 and 5 to 15 ni~crons
1, 2, 3, 4, 5, 6
J
Infrared, 2 to 16 microns Ultraviolet, 2200 to 4000 A.
1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5 , 6
K
Infrared, 1.65 to 2.0 microns Ultraviolet, 2200 to 4000 A.
1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5 , 6
L.
Infrared, 2 to 15 microns Ultraviolet, 2200 t o 4000 A.
1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5, 6
M
Infrared, 2 to 14 microns Ultraviolet, 2000 to 4000 A.
1, 2, 3, 4, 5. 6 1, 2, 3, 4, 5, 6
N
Infrared, 2 to 15 microns Ultraviolet, 2000 to 4000 A.
1 , 2, 3, 4, 5, 6 1, 2, 3 , 4, 5, 6
Table 111. Mass Spectral Analysis of Sample 1 by Laboratory A and of Samples 1, 2, 3, 4, 5, and 7 by Laboratory F" No. of Carbon Atoms per Molecule 21 22 23 24 25 26 27 28 29 30 31 32 33 34
35
36 37 38 39 a
Lad.A, vO1.
..
..
..
2
%
2 4 6 8 8 11 17 17 13 9 4 1
.. .. .. ..
Sample 1
..
2 4 7 14 26 24 12 7 3
1
.. .. ..
.. ..
..
1 2 4 9 19 23 18 13 8 3
.. .. .. .. ..
3 4 Lab. F., Vol. %
.. .. ..
1 5 8 14 21 20 14 10 5 2
..
1 3 4 9
14
..
17 17 13 10
..
4
..
..
..
J
7
.. ..
..
2 4 9 17 19 19 16 9 4
. 1.
..
..
7
.. ..
1
..
From interpretation of parent-peak portion of spectrum.
..
1 1 2 4 6 8 14 26 15 12 7 3 1
M a y 1955
INDUSTRIAL AND ENGINEERING CHEMISTRY
with respect t o molecular weight. Therefore, the spread in number of carbon atoms per molecule given for sample 7 in Table I11 is representative of t h a t of each of fractions 7a t o 7i. I n Table VI, a comparison is given of the values of n and x in the average molecular formula, CnHzn+ obtained by Laboratory F from mass spectral data, with those obtained by the API Research Project 6 from precise values for the carbon and hydrogen content and the molecular weight. It appears t h a t the two methods are in good agreement, with a maximum difference of 0.8 in the number of carbon atoms and a maximum difference of 0.3 in the value of 2.
1065
Table IV. Mass Spectral Analysis of Sample 1 by Laboratory A and of Samples 1, 2, 3, 4, 5, and 7 by Laboratory Fa Rnmnle ~
Type of Hydrocarbon
1
Lab. A, Vol. %
1
Normal paraffins Branched paraffins Monocycloparaffins Dicycloparaffins Trioyclo paraffins Tetra- and higher cycloparaffins Aromaticsb
1 31 32 21 10 5
3i
38 18 9 4 .
..
. -
2 3 4 5 Lab. F, Vol. %
ii
..
i5
28 29 25 25 18 16 16 12 . 2 3
7
26 25 17 16 2
2 ii 22 27 20 21 20 16 31 15 5 2
From interpretation of parent-peak portion of spectrum. b Alkylbeneenes and other mononuclear aromatics containing cycloparaffin rings. a
WATER-WHITE OIL PORTION
Table V.
Mass Spectral Analysis of Samples 7a to 7i, Inclusive, by Laboratory F"
SYSTEMATIC FRACTIONAL DISTILLATION AT LOW PRESSURE
FRACTIONS OF DISTILLATE
REFLUX EXTRACTION
WITH ACETONE
T F I N A L FRACTIONS
Type of Hydrocarbon Branched paraffins h'Ionocycloparaffins Dicycloparaffins Tricycloparaffins Tetra- and higher cycloparaffins Aromaticso
7a
7b
7c
Sample 7d 7e 7f 79 7h 7i Percentage by Volume
36 26 21 18 17 32 28 24 27 23 19 24 24 23 22 7 13 16 16 18 5 1
8 1
14 1
14 2
18 2
Av.b
7
14 19 23
18 24 22 16
18 27 21 16
17 21 27 32 3 4 4 7
17
16
15 13 10 23 22 18 24 23 20 18 17 21
5
3
2
From interpretation of parent-peak portion of spectrum. 6 Based on assumption t h a t all fractions from thermal diffusion separation were of same volume. Alkylbenzenes and other mononuclear aromatics containing cycloparaffin groups. a
REFLUX EXTRACTION WITH METHYL CYANIDE
Figure 2.
T
Schematic diagram of separation of waterwhite oil portion of lubricant fraction FINAL
N u m b e r e d blocks in lower p a r t of figure refer t o samples investigated spectroscopically
Table VI1 gives results obtained by Laboratory F from a n interpretation of the fragment-peak portion of the spectrum. This interpretation gives t h e amounts of paraffins, noncondensed cycloparaffins, and condensed cycloparaffins (five- or six-membered rings in which two or more carbon atoms are shared). I n addition t o these, a n estimate of the ratio of cyclopentyl t o cyclohexyl groups as free structures (not p a r t of condensed ring structures) is reported. Table VI11 gives results obtained by Laboratory A from a combined analysis of t h e parent-peak and fragment-peak portions of the mass spectrum. With this procedure, there are obtained t h e amounts of paraffins, noncondensed cycloparaffins, and condensed cycloparaffins, with t h e latter being determined according t o the number of rings per molecule. The value for t h e ratio of noncondensed t o condensed cycloparaffins obtained by Laboratory F (see Table V I I ) is considerably higher than t h a t obtained by Laboratory A (see Table VIII). By combining some of the results given in Table IV with those given in Table VII,
I
FRACTIONS
n
-
Figure 3.
I -
I
Schematic diagram of separation of extract oil portion of lubricant fraction
N u m b e r e d block in lower part of figure refers to s a m p l e investigated spectroscopically
1066
INDUSTRIAL AND ENGINEERING CHEMISTRY
Table VI. Values of n and x i n Formula by Two Different Methods Sample
No.
-
1 2 3 4 5 7
as Given
Value of 5 in formula CnHzn+ APIRPGa Lab. Fb 0.0 -0.3 -2.0 -2.2 -1.9 -2 0 -2.0 -2.2 -4.0 -3.9 -1.9 -2.1
Value of ~tin Formula CnHm+ z APIRPGa Lab. F b 27.8 27.4 27.6 27.2 29.8 29.6 34.4 33.7 27.7 27.4 29.8 29.0
a From precise measurements of molecular weight and content of carbon and hydrogen. b From mass spectral data.
1.4850-
0:
/
1.4800-
u-3 c\I L
C0' U
1.47501
X'
ORIGINAL
Vol. 47, No. 5
The data indicate (see Table VII) a ratio of cyclopentyl to cyclohexyl groups (present as free structures) of nearly 2 t o 1. This result does not appear t o be consistent with the results from the infrared examination and is discussed further in the following section. Ultraviolet and Infrared Spectral Examination. Table IX gives a brief summary of the comments and conclusions of a number of the cooperating laboratories from a consideration of their ultraviolet and infrared spectral data on samples 1, 2, 3, 4, and 5. These results are in accord with those from the mass spectral data in indicating t h a t the samples are composed almost entirely of saturated hydrocarbons with very small or trace amounts of aromatics in samples 1, 2, 3, and 4 and with slightly more in sample 5. In addition to the results given in Table I X , Laboratories B, D, L, and I interpreted their infrared spectral data for samples 1, 2, 3, 4, and 5 to give semiquantitative values for the number of various groups or the ratio of certain groups in the average molecule. These results are given in Table X. Laboratories D and L used a procedure similar to t h a t described by Hastings, Watson, Williams, and Anderson ( 2 )as modified by Francis ( 1 ) .
Table VII. lMass Spectral Analysis of Samples 1,2, 3, 4, 5 , and 7 by Laboratory Fa
d
1
%
Type of Hydrocarbon Paraffins
1 1.4700
Noncondensedoycloparaffins
Condensed cycloparaffins .4romaticn Ratios: .~~ ~ ~ cyclopentyl . . .groups ~~~
28 56 16
..
Sample 2 3 4 5 Percentage by Volume 11 56 31 2
15 55 29
1 j $
15 56 28 1
2 46 46 $5
7 19 50 30
.T1
cyclohexyl groups 44 39 35 39 28 From analysis of fragment-peak portion of spectrum. b Ratio of cyclopentyl t o cyclohcxyl groups is for free structures (not part of condensed structures). a
Table VIII. Mass Spectral Analysis of Samples 1, 2, 3, 4, and 5 by Laboratory A" I
I
I
I
I
I
I
I
FRACTIONS Figure 4. Results of fractionation of sample 7 by thermal diffusion in liquid phase
t h e percentage of the total polycyclic cycloparaffin portion comprised by the condensed cycloparaffins may be obtained. For the several samples these values in percentage by volume are sample 1, 55; sample 2, 54; sample 3, 53; sample 5, 65. The results of the mass spectral examination of samples 1, 2, 3, 4, 5, and 7 show t h a t the separation effected by distillation and by solvent extraction of t h e water-white oil portion of t h e lubricant fraction was less complete, and t h a t the samples were less homogeneous with respect to size and molecular type than had formerly been thought. T h e conclusions of the API Research Project 6, t h a t the water-white oil portion of the lubricant fraction was composed largely of Cycloparaffins with from about one t o three rings per molecule, need some revision, as i t is now apparent that this material also contains some branched paraffins as well as some cycloparaffins with four or more rings per molecule. The mass spectral examination of samples 7a t o 7i shows t h a t the thermal diffusion process produced a considerable separation of sample 7 . However, the separation was still far from complete; all of the types occurring in the original sample were present in each of the nine fractions separated therefrom. T h e data also indicate t h a t both condensed and siqgle ring structures are present in roughly equal amounts in t h e polycyclic cycloparaffins.
1
Type of Hydrocarbon
Sample 2 3 4 Percentage b y Volume
.-
5
Aromatics 0 1 1 1 3 a From combined analysis of fragment-peak and parent-peak portions of spectrum.
According t o this procedure, the content of CHa groups is obtained from t h e infrared absorptivity a t 7.254 microns, and the content of paraffinic CH2 groups is obtained from the integrated absorptivity in t h e region near 13.8 microns (12.5 to 14.3 microns for Laboratory D and 12.59 to 14.67 microns for Laboratory L). Cyclohexyl and cyclopentyl CH, groups are determined from the absorptivities at 3.382 and 3.418 microns, after correcting for the contributions due to CHI and paraffinic CH2 groups a t these wave lengths. This analysis is possible as a result of the fact t h a t cyclohexyl CHZ groups have their maximum absorption a t 3.418 microns, while cyclopentyl CH2 groups have their maximum absorption at 3.382 microns. For Laboratory I, t h e percentages of CHI and CH2 groups in the samples were determined principally from absorptivity in the region 1.1 microns, corrections being made for the presence of cycloparaffin rings as suggested by Hibbard and Cleaves (3). No information was obtained regarding the nature of the cycloparaffin rings. T h e percentages of n-butyl and higher groups, determined at 13.8 microns, appear in column 8. These values are similar t o those of column 7 (total number of paraffinic CHa
May 1955
.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Table IX. Summary o f Comments on Infrared and Ultraviolet Spectral Analysis o f Samples from Water-White Oil Portion Laboratory Comments B The presence of some aromatics (4to 5 % ) in sample 5 , and very small amounts of aromatics in samples 1, 2, 3, and 4, is indicated by ultraviolet spectral data. Infrared spectral data confirm the presence of aromatics in sample 5 . Samples 7a to 7i show absorption peak at 5.7 microns, indicating low degree of oxidation (see also Tables X and XI). D A group anaIysis is given in Tables X and XI. Samples 7a to 7i contain small amounts of oxygenated compounds (1 to 3%).
E
G H
I J
L N
The presence of a small amount of aromatics in samples 1, 2, 3, 4, and 5 is indicated by ultraviolet spectral data. Infrared spectral data indicate average unsubstituted chain length in carbon atoms per molecule to be 8 to 10, 6, 6, 6, and 5 , for samples 1 , 2 , 3, 4, and 5 , respectively, and average number of CHs groups per molecule to be 3.2, 3.2, 3.3, 4.2, and 4.2 for samples 1, 2, 3, 4 , and 5, respectively. The infrared spectral data indicate unsubstituted chain length in carbon atoms per molecule to be 6 or more for samples 1, 2, 3, 4, and 5. The presence of aromatics (about 5%) in sample 5 is indicated by both ultraviolet and infrared spectral data. In addition, sample 5 contains a trace of oxygenated compounds. The unsubstituted chain length in carbon atoms per molecule is indicated to be from 3 to 7 for samples 1, 2, 3, 4, and 5 . None of the samples 1 , 2, 3, 4, or 5 contain significant terminal branching. Internal branching may be present and may vary slightly from sample to sample, sample 1 showing most branching and sample 5 least branching. Group analysis given in Table X. The presence of aromatics (about 3%) is indicated in sample 5. Unsubstituted chain length in carbon atoms per molecule is indicated to be 8 or more for samples 1, 2, 3 , 4, and 5 . Branching or cyclic structure may be present but is not directly in evidence. A group analysis is given in Table X. A small amount of aromatics is present in sample 5 , and still smaller amounts in samples 2, 3, and 4. The presence of aromatics is indicated in sample 4 (a trace) and in sample 5 (about 3%). Unsubstituted chain length in carbon atoms per molecule is indicated to be 4 or more for samples 1, 2, 3, 4, and 5.
1061
Table X. Analysis, by Groups in Average Molecule, of Samples 1, 2, 3, 4, and 5, as Determined by Laboratories B, D, I, and L No. of CHs Sample
Lab.
D
Groups Lab. L
Lab.
I
Total No. of CHz Groups in Paraffinic Chains Lab. Lab. Lab. D L I
No. of,CHz Groups In Para~~~~~~~ 4 Carbons, Lab. I
No. of Groups per Average Molecule 1 2 3 4 5
4.1 4.9 5.0 5.8 5.6
3.3 4.1
5,O
5.8 5.2
4.4 4.9 5.0 5.4 4.9
17.0 13.2 15.1 18.2 11.2
17.1 11.6 14.6 15.6 12.1
17.2 12.1 14.8 17.8 11.2
18.1 11.8 14.2 16.4 8.2
No. of CHZ Groups per Average Mo@ I n Rings of 6 Carbon Atoms Total, Lab. Lab. ' Lab. I D L 1.1 1 18.9 1.7 2.6 2 15.7 3.0 3.0 3 17.5 3.9 4 21.2 5.1 4.4 0.2 5 13.7 3.3 a Calculation based on assumption
I n Rings of 5 Ratioa of Carbon Atoms C H ~G ~ Lab. Lab. CH2 Groups, D L Lab. B 1.1 0.20 -0.6 0.3 0.4 0.30 -1.0 0.25 0.0 -0.3 -1.8 0.26 -1.3 0.36 -0.8 t h a t samples are paraffinic (see text).
However, the mass spectral analyses indicate t h a t the samples contain substantial amounts of noncondensed cycloparaffins, and t h a t cyclopentyl groups predominate over cyclohexyl groups when these groups are present in noncondensed structures. For such free ring structures, accounting for the presence of CH2 groups in cyclohexyl b u t not in cyclopentyl rings would require t h a t the cyclopentyl rings be completely substituted, and the cyclohexyl rings little substituted. This is possible, but not very reasonable, and i t seems more logical to conclude t h a t the mass spectral d a t a and the infrared spectral data are not in complete accord regarding the content of cyclopentyl rings. It appears t h a t all the fractions are.too complex to permit a more complete picture of t h e structure of any one type of hydrocarbon to be obtained from a consideration of the percentages of the various groups as given by the infrared spectral data. When fractions which are homogeneous with respect to type and size of molecule become available, the results of a combined infrared and mass spectral examination should prove useful in obtaining a more complete picture of the structure of each individual type of molecule. EXAMINATION OF EXTRACT OIL PORTION
groups) for samples 1 t o 4, indicating t h a t the CH2 groups are predominantly in groupings of a t least four unsubstituted carbons. By t h e same reasoning, sample 5 should have more of its paraffinic CH2 groups in shorter groupings. There are also included in Table X (column 14) values for the ratio of the number of CHa groups to t h e number of CH2 groups in the average molecule, calculated by Laboratory B from observations of t h e absorptivity at 3.38 and 3.42 microns on the assumption t h a t these samples are paraffinic. Table XI gives the results of a n analysis b y groups in the average molecule by Laboratory D, and the results obtained by Laboratory B for the ratio of the number of CH, t o the number of CH2 groups, for samples 7a t o 7i, inclusive. There is general agreement (see Table I X and columns 7 and 8 of Table X ) t h a t the paraffinic CH2 groups are contained predominantly in unsubstituted chains at least four carbon atoms in length. T h e results for the content of CH2 groups in rings (see Table X and Table XI, columns 4 and 5) indicate t h a t these groups are present in significant amounts in rings of six carbon atoms but t h a t few or none (in some cases negative amounts are indicated) are present in rings of five carbon atoms. This need not mean t h a t cyclopentyl rings are absent if these rings are so highly substituted or condensed t h a t they contain no CH2groups.
M a s s Spectral Examination. The results obtained by Laboratory F from a n interpretation of the parent-peak portion of the mass spectrum of sample 6 are given in Tables X I 1 and XIII. Table X I 1 gives the percentage of the total sample constituted by the components according t o the number of carbon atoms per molecule, while Table XI11 gives the percentage of each type
Table XI. Analysis, by Groups in Average Molecule, of Samples 7a to 7i, Inclusive, as Determined by Laboratories B and D No. of CHz Groups per Average Molecule, Lab. D Ratio5 of No. of CHs Total in I n rings of I n rings of CHa/CHp 6 carbon 5 carbon Groups, groups, paraffinic chains atoms atoms Lab. B Sample Lab. D 7a 4.4 20.5 1.8 -0.6 0.22 7b 5.3 1.8 -1.5 0.21 18.1 7c 5.3 16.6 2.1 -1.5 0.25 2.1 -0.9 0.26 7d 5.3 16.3 7e 5.5 15.7 3.3 -0.6 0.24 3 . 3 0 . 9 0.26 71 40 .. 8J 15.1 79 14.5 3.3 -0.3 0.25 7h 5.8 13.6 3.3 -0.9 0.28 3.6 -1.2 0.31 7i 6.1 12.2 Calculation based on assumption t h a t samples are paraffinic (see text).
~
INDUSTRIAL AND ENGINEERING CHEMISTRY
1068
of hydrocarbon in the total sample. I n addition, from an analysis of the fragment-peak portion of the spectrum, Laboratory F reported t h a t sample 6 contained 7% of condensed cycloparaffins, 87% of mononuclear aromatics, and 6% of dinuclear aromatics. Laboratory A reported for this sample a content of 6y0 of cycloparaffins and %yoof aromatics, in good agreement with the results of Laboratory F.
Table XII. Mass Spectral Analysis of Sample 6 by Laboratory Fa No. of carbon atoms per molecule Vol. 7 0 a
24 25 26 27 28 29 30 31 32 4 12 22 23 19 12 6 2 1
From analysis of parent-peak portion of spectrum.
Table XIV. Summary of Comments on Infrared and Ultraviolet Spectral Analysis of Sample 6 from Extract Oil Portion Laboratory Comments B The resemblance of the ultraviolet spectrum to spectra of substituted tetrahydronaphthalenes agrees with proposal that this fraction contains one aromatic ring per molecule. However, absorption peaks between 3200 and 3300 A. may be associated with substituted naphthalenes E In the infrared spectrum, there is evidence of both condensed and noncondensed aromatic ring structures. Unsubstituted chain length in carbon atorns per molecule is 6 or more, and average number of CHs groups per molecule is 2.8. G
Table XIII. Mass Spectral Analysis of Sample 6 by Laboratory F a Amount, Vol. 70 Alkyl benzenes 11 Monocycloparaffin-mononuclear aromatics 17 Dicycloparafin-mononuclear aromatics 17 Tricycloparaffin-mononuclear aromatics plus alkylnaphthalenes 20 Tetra- and higher cycloparaffin-mononuclear aromatics plus 35 mono- and higher cycloparaffin-dinuclear aromatics Type of Hydrocarbon
a
H
From analysis of parent-peak portion of spectrum.
The results of the mass spectral examination of sample 6 show t h a t this material is composed largely of molecules with one aromatic ring attached to from zero to four or more cycloparaffin rings, together with appropriate paraffin side or connecting groups. Small amounts of condensed dinuclear aromatics are also present. These results confirm the conclusion of the API Research Project 6 t h a t sample 6 consists largely of molecules containing one aromatic ring attached to cycloparaffin rings (2l/2 on the average) and to paraffin side and connecting groups. Ultraviolet and Infrared Examination. Table XIV gives, for sample 6, a brief summary of the comments and conclusions received from the cooperating laboratories from a consideration of their ultraviolet and infrared spectral data. Most of the laboratories agree t h a t this sample consists principally of mononuclear aromatics together with a small amount of condensed dinuclear aromatics. Additional information concerning the structure of the aromatics cannot be regarded as definitely established from the infrared or ultraviolet spectral data. COMPOSITION O F LUBRICANT FRACTION OF PETROLEUM
From the earlier work of the API Research Project 6 ( 9 , 10) and the results of this spectroscopic investigation, a new approximate analysis of the lubricant fraction with respect to kinds of molecules can be made. These results are given in Table XV. ACKNOWLEDGMENT
Grateful acknowledgment is made to the 15 cooperating laboratories for their considerable assistance in this work. LITERATURE CITED (1) Francis, S. A., Ana2. Chem., 25, 1466 (1953). (2) Hastings, S. H., Watson, A. T., Williams, R. B., and Anderson, J. A., Jr., Ibid., 24, 612 (1952). (3) Hibbard, R. R., and Cleaves, A. P., Ibid., 21, 486 (1949). (4) Mair, B. J., and Schicktanz, S. T., J . Research Natl. B u r . Standards, 17, 909 (1936). (5) Mair, B. J., and Willingham, C. B., Ibid., 17, 923 (1936). (6) Ibid., 21, 535 (1938). (7) Mair, B. J., Willingham, C. B., and Streiff, A. J., Zbid., 21, 565 (1938). ( 8 ) Zbid.. p. 581.
Vol. 47, No. 5
The material is probably mostly substituted aromatics, such as derivatives of benzene, tetrahydronaphthalene and/or diphenyl, with about 1 to 5% of substituted naphthalenes. A minor amount of oxygenated compounds is also present. The infrared spectral data suggest that aromatics in this sample consist largely of polysubstituted benzenes plus some monosubstituted benzenes, or as a complex fused ring structure, partially cycloparaffin, about which little is known. This conclusion is confirmed by ultraviolet spectral data which also indicate presence of a small amount (about 4%) of substituted naphthalenes. A minor amount of oxygenated compounds is also present.
I
Ultraviolet spectral data show about 10% by weight of compounds with naphthalene nucleus and 90% with benzene nucleus. Both nuclei are probably fused to cycloparaffin rings, andit seemslikely that the benzene ring is terminal in chain of fused rings. The infrared absorption a t 1.1 microns, for aromatic CH groups, shows that aromatic rings are highly substituted.
J
A small percentage (probably less than 10%) of molecules present contain naphthalene ring structure, in which rings are at least disubstituted. The remainder of the material comprises one or more of the following or related structures: tetrahydronaphthalenes, indans, tetrasubstituted benzenes, or polysubstituted diphenyls. Mono- and disubstituted benzene rings are not present in appreciable amounts.
L
The ultraviolet spectra are consistent with the interpretation that an appreciable fraction of the molecules contain a benzene ring fused to a cycloparaffin group, although other types of structure might also explain data. The ultraviolet and infrared spectral data indicate the presence of one aromatic ring per molecule. Carbonyl compounds (about 1%) are present.
N
Table XV. Approximate Average .4nalysis, with Respect to Kinds of Molecules, of Middle Part o€ Lubricant Fraction Containing 25 to 35 Carbon Atoms Type of Hydrocarbona
Val. 70 of Lubricant Fraction 13.7 8.3
Normal Daraffins Branched paraffins 18.4 Mnnonvnlnnaraffins ._.~~..“ . 9.9 Dicycloparaffins 16.5 Tri- and higher cycloparaffins Mononuclear aromatics with cycloparaffin rings Dinuclear aromatics with Cycloparaffin rings Trinuclear aromatics with cycloparaffin rings Multiring aromatics, very low in hydrogen, with bulk of nonhydrocarbon material Total
.~..~..~~~~~ ~
\
’
0
44.8 10.5 8.1
6.6 8.0 100.0
Including, as appropriate, necessary paraffin side or connecting groups.
(9) Rossini, F. D., Proc. Am. Petroleum Inst., 19, 111, 99 (1938). (10) Rossini, F. D., Mair, B. J., and Streiff, A. J., “Hydrocarbons from Petroleum,” Reinhold, New York, 1953. RECEIVED for review August 18, 1954. ACCEPTED December 9,1954. P a r t of work of American Petroleum Research Project 6 in t h e Petroleum Research Laboratory, Carnegie Institute of Technology, Pittsburgh, P a .
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