I)elieved tile accuracy is of the saillc: oydcr of magnit,ude a s tha,t of the synthetic samples. LITERATURE CITED
(1) hssoc. Offic. Agr. Chemists, "Official ?*lethods of Analysis," 7th ed., 1950. (2) C a d , C. C., J . dssoc. O j i c. Agr. Chemists 20, 171 (1937). (3) Chaney, -4.L., Magnuson, H. J., IND.ENG.CHEII., ANAL. ED. 12,
691 (1940).
(4) Ho\v,A. IC., [bid., 10, 226 (19i38). ( 5 ) H11t)t)ard, D. 11.1 [bid., 13, 915 (1941). (6) Jay, R. It., Dickson, I,. It., Petrolemi Processing 9, 374 (1952). (T) Lachele, C. E., I s u . KXG. CIIEM., . ~ s A I , . ED.6, 256 (1934). (8) Niteching, E. H., Flinn, F. 13., J . Lab. Clin. .\led. 15, ii9 (1930). (I))Morris, H. ,J., Calvcry, H. O., ISD. ENG.CHEAT., .4x.i1,. ED. 9 , 447 (1937).
(10) Itodgew, D., IIcron, .1. E., .IriaZyst 71, 414 (1946). (11) Satterlee, €1. J., Hlodgett, G . , ISD.
ESG. CHEAT.,. 4 s a ~ .ED. 16, 400 (1944).
(12) Scott,, W. IT., "Standard Methods of Chemical Analysis," 5t.h ed., pp. 99, 115, Van Nostrand, Yew I'ork, 1939. (13) Smith, D. G., British Petroleum Co., London, England; private conirniiiiication (1952).
RECEIVEDfor review June 11, 1956. Accepted December 26, 1956. Group Session on Analytical Research, Division of Refining, American Petroleum Institute, Montreal, Canada, Ma>- 1956.
Hydrocarbons in the 116" to 126" C. Fraction of Petroleum AUGUSTUS R. GLASGOW, Jr.,l RAYMOND J. GORDON, CHARLES B. WILLINGHAMI2 BEVERIDGE J. MAIR, and FREDERICK D. ROSSlNl Petroleum Research laboratory, Carnegie Institute of Technology, Pittsburgh I 3, Pa.
Twenty-two hydrocarbons were found in the fraction of petroleum normally boiling between 116" and 126" C. This fraction of petroleum constitutes approximately 5.37% by volume of the representative petroleum which has been under investigation for many years by the American Petroleum Institute Research Project 6. These compounds were concentrated by extended use of the fractionating processes of regular and azeotropic distillation. Identification of the compounds was made by mass and infrared spectrometric examination, together with measurements of the simple physical properties. The names and estimated relative amounts by volume of the twenty-two compounds, given in order of decreasing amount in the petroleum, are as follows: n-octane, 35.5; 2-methylheptane, 1 6.7; 1,cis-3-dimethylcyclohexane, 1 1.8; 1 ,trans-2-dimethylcyclohexone, 5.8; 3-methylheptaneI 5.6; 1 ,trans-4-dimethylcyclohexane, 4.5; 4methylheptane, 3.7; 1 ,trans-2-ethylcyclopentane, 2.5; 3,4-dimethylhexane, 2.4; 1 -methyl-trans-3-ethyIcyclopentane plus 1 -methyl-cis-3-ethylcyclopentane, 2.3; 3-ethylhexaneI 1.7; 1 ,cis - 4 - dimethylcyclohexane, 1.6; 1 ,frans-3-dimethylcyclohexane, 1.3; 1,cis - 2,trans - 3 trimethylcyclopentane, 1.3; 1,l -dimethylcyclohexane, 1.2; 1 ,1,cis 2,trans- 4 tetramethylcyclopentane, 0.8; 1 -methyl- 1 -ethylcyclopentane, 0.6; 3-methyl-3-ethylpentaneI 0.3; 1 ,cis-2,frans-4-trimethylcyclopentane, 0.2; cycloheptane, 0.1 5; 2,2,5trimethylhexane, 0.03. In addition,
-
-
-
trace amounts of an unidentified bicycloparaffin occur in the distillate fraction boiling near 124.5" C.
A
p . 4 ~of~ the continuing work of the American Petroleum Institute Research Project 6 on the composition of its representative petroleum (7), analysis has bccn eomplcted of the hydrocarbons in that fraction of this petroleum normally boiling betn cen 116' and 126' C., nhich constitutes approximately 5.37% by voluinc of the original
s
petroleum. An early invrstigation ( 4 ) revealed the presence of four hydrocarbons in this fraction: 2-niethylheptanc at 117.65" C.; l,cis-3-dimetliylcyclohexane at 120.09' C.; l,trans-2-dimetliylcgclolie\ane :it 124.45' C.; and noctane a t 125.66' C. The present in\ estigation of this portion, using distillation equipment of much greater separating efficirncy than \\as earlier available, in conjunction \\ ith the modern spectroscopic mcthodq of analysis has shov n that it contains 22 hydrocarbons. The dctnils of the :inalysii of thc adjacent Ion er lioiling portion arc given in (3), and tliow of the :icljncciit highrr boiling portion in ( 2 ) . PROCEDURE
=ill of the paraffin-cycloparaffiIi material remaining from the earlicr in\-rstigatioii (4) was combined and distilled a t 725 nini. of mercury. Further processing of this material by distillation (regular, azeotropic. and at reduced pressure) was designed to concentrate the indi-
vidual 11) dioc:irhiib SO that they could be identified 11 ith reasonable certainty. The apparatus and procedurrs used in the distillations are drscribed in ( 8 ) . These distillation oprrations required the repeated blending of portions of distillate to product charges for redistillation. d total of 55 charge< n:ts prepared :ind cliatillcd. The amounts of the indi\.idiial conipounrls \\-rr(' coniputed from thc r t w l t s of ipwtrographic analyses (principally mass spectra, with ~ n i infrared c spectr:i) made for L I on ~ a total of j i intc~rmediatc~ and final frnctions by the Rcsearch 1,aI)oratoi-y of the Humble Oil :lad R h i i n g Co. In addition t o the -pcctrobcopic :in:ily.eq, the cr:d coinpounds \ r a t determincti from nic~isuremtnt~of the freezing point. Thc dttails of t h c v operations givtw in a rc>port of thv ilnierican Petrolvuni Iiiititutcx Ilriearch Project 6. c n t i t l d "Hydrocarbon. in the 116" to 126' C.Fraction of PctroIruni". dated AInrch 31, 1952, 11 hich is a v d a h l r from the Petrolrum Rpsearcli Laboratory, Carnegit, Inatitiitc. of Technology, Pittsburgh, Pa. The results of the distillation of the starting material are given in Figlire 1. I n this figure, the solid lines refer to the distillation a t 725 mni. of mercury. and the dashed lines refer to the redistillation of a portion of the material at 30.5 mm. of mercury. It will be noted that the distillation at 30.5 nim. of inercury \vas very effectiw in separating the re1 Piesent iddress, Satioiiitl Rineau of Standards, Kashington 25, D . C 2 rlddrees, llellon Institute 01 Industrial Research, Pittsliurgh 13, Pa.
VOL. 29,
NO. 3,
MARCH 1957
357
I -
o 0
z 38 2 I
2m I-
a
+
z0
36
a
0
z
=! 0
m
-nD
34
.44
32
.43
.42
9 In N
I-
d
cl
c
AI
x-x Z
w
II-
o
i, 110
I
I
I
I
I
I
I
1
I
I
I
a
11:
LL
I40
I
I
!$
1.39
Upper and lower solid lines give, respectively, boiling point and refractive index of distillate, with respect to its volume, obtained in regular distillation a t 7 2 5 mm. Hg. Upper and lower broken lines near right side of flgure give, respectively, boiling point and refractive index of distillate, with respect to its volume, obtained in distillation a t 30.5 mm. Hg of indicated portion of material.
maining n-octane from the cycloparaffins which immediately precede it in normal boiling point. The methods employed for the separation of the individual hydrocarbons are illustrated for one compound, cycloheptane, in Figures 2 and 3. The material from the preliminary distillation normally boiling in the range from 117.0" to 117.8" C. (portions A and B , Figure 1) were distilled azeotropically with ethyl
358
ANALYTICAL CHEMISTRY
alcohol to give the results shown in Parts I and I1 respectively, of Figure 2. The refractive indices of portions IA and IIA from this distillation were higher than those of the alkyl cyclopentanes and alkyl cyclohexanes which boil a t or near this temperature and it was suspected that this material contained cycloheptane which normally boils a t 118.79' C. (6). The further concentration of this material by aeeotropic
distillation is shown in Figure 3. The refractive index, nD a t 26" C., of the material near the end of the distillate (portion B , Figure 3) was 1.4400 which may be compared with the value 1.4424 for cycloheptane (6). The molecular n-eight of portion B , determined by the freezing point method using o-xylene as a solvent, was found to be 98.0 1.4 which is to be compared with the value 98.18 for pure cycloheptane. The other
*
I
I
I
I
I
1 I
I
74.6
PART I
I I
PART
I1 II II
/I II I1
'i
I
I
A
A
1
I 0
500
500
100
I 1500
IO00
VOLUME OF HYDROCARBON IN ML.
Figure 2. Results of azeotropic distillation of portions A and 5 from Figure 1
nDi/
I
CYCLOHEPTANE CONCENTRATE
____, Figure 3. Results of the azeotropic distillation of portion A from Figure 2
1
1 I
1 10
I
I
I 20
I 30
J
VOLUME OF HYDROCARBON IN M L. VOL. 29, NO. 3, MARCH 1957
359
~~
Table I.
~
~~
Summary of the 22 Hydrocarbons Found in the 1 16" to 126' C. Fraction of Petroleum
Componenta
Formh
Boiling Point of Pure Compouiid at 1 Atm., C.
Highest Concentration
84
1, czs-2,t~ans-4-Trimeth~ lcyclopentane 1,cis-2,trans-3-TrimetIi~lc!-clopeiitane
2-Rlethylheptane 4-Methylheptane 3,CDimethylhexane 3-Methyl-3-ethylpen tane 3-Ethvlhexane Cycloheptane 3-Methylheptane l,trans-4-Dimethylcyclohexane 1,l-Dimet hylcyclohexane 1,cis-3-Dimethylcyclohexane 1-Methyl-trans-3-ethylcyclopen tane 1-Methyl-czs-3-ethylcyclopentaiie 1-Methyl-trans-2-ethylcycloperitarie 1-Methyl-1-ethylcyclopentane 1 1,cis-3,trans-4-Tetramethylc!-clo-
Isolatedib llole ( L
118 2ti 118 53 118 79 118 92 119 35 119 54 120 OR 120 8" 121 4) 121 2 121 52
90 85 34 40 6 43 90 98; 97b cIJ
84 84; 85'' 57 i4
Estimated Relative Amount by Volume i n 116' to 126" C. Fraction
Amount in Original Crude Petroleum,c Percentage by \'oliime
0 2 1 3 16 7
3 7 2 4 0 3 1.7
0.15 5.6 4.5 1 2
11.8 2.3 2.5
65
0.6
83
0.8 5 .8 0 03
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
01 0i 90 20
0 0 0 0 0
04
13 02 09 01
30 25
06 G3
12 14 03
~
pentane l,trans-2-Dimethylcyclohe~ane 2,2,5-Trimethylhexane 1,cis-4-Dimethylcyclohesane l,trans-3-Dimethylcyclohe.;nne n-Octane Total
CsHis
121 G 123 42
98; 9Gh
11
i0
49 99 2
.
1.6
1.3 35.5 100.0
31 002 09 07
1 9 5 372
2,3-Dimethylhexane at 115.61' C. and 2-methyl-3-ethylpentane at 115.G5"C., which were isolated previously froin the 108" to 116" C. io1 this additional quantity of these coiistitiients ( 7 ) . I n addition, trace amounts of an unidentified bicycloparaffin occur in the distillate tracations boiling near 124.5' C. These values were determined from measurements of freezing points. A11 othei values in this column aere determined fiom spectral data. Amount of given component in gasoline fraction, 40' to 180" C., is about three times value given in this column.
(S), are also present in this fraction. Records have been adjusted to account
hydrocarbons which are possible in this region contain eight carbon atoms per molecule and have the following molecular weights: bicycloparaffins, 110.19; monocycloparaffins, 112.21 ; and paraffins, 114.22. The material was subsequently identified as cycloheptane by spectroscopic analysis and estimated to have a purity near 90%. I n this petroleum the cycloheptane was associated principally with Zmethylheptane; 4methylheptane; and 3,i-dimethylhexane, and was located in distillate fractions boiling slightly more than 1" C. below the boiling point of pure cycloheptane. A displacement of the boiling point of cycloparaffins in petroleum distillates is not unusual and may be attributed to the nonideality of dilute solutions of cyclopnrnfins in p:mffiiis ( 5 ) . RESULTS OBTAINED
Table I summarizes the information regarding the twenty-two hydrocarbons found in the 116" to 126' C. fraction of petroleum. Bell ( 1 ) . using somewhat similar methods, has reported the presence of 17 hydrocarbons in the corresponding fraction of an East Texas petroleum. The data in Table I lead t o the following conclusions. (a) The material is composed almost entirely of five types of hydrocarbons in the follow-
360
ANALYTICAL CHEMISTRY
ing relative aniounts by voluiiie: normal paraffins, 36; branched pamffins, 30; alkyl cyclopentanes, 8; alkyl cyclohexanes, 26; and cycloheptane, 0.15. ( b ) I n addition to the twenty-two hydrocarbons found, the only other hydrocarbons of the paraffin, alkyl cyclopentane, and alkyl cyclohexane classes normally boiling in the range 116' to 126' C. are the following (6), which are believed to be present only in trace amounts: 1,1,- 3,3 - tetramethylcyclopentane at 117.96' C.; 1,cis-2,cis-4-trimethylcyclopentane a t 118' C.; 2,2,4,4-tetramethylpentane a t 122.28' C.; and l,cis-2,cis3-trimethylcyclopeiitane a t 123" C. ( e ) The singly branched, doubly bmnched, and triply lxanched paraffins are present in this gasoline fraction in relative amounts which have magnitudes ns follows: 100, 10, and 0.1, respectively. ( d ) Cycloheptane is present in very sniall amounts. Tliis is the first t h e that this compound or any of its derivativrs has been identificd in petroleum. (e) A bicycloparaffin boiling near 124.5' C. is prcsent in trace amounts. This is the lowest boiling bicycloparaffin to 1w tletec t cd in p~ t rolcu 111. ACKNOWLEDGMENT
Grateful ackiiowledgment is made t o the Resc~trchLaboratory of the Humble
Oil and Refining Co., Baytown, Tes., for the spectrographic analyses reported in this paper. LITERATURE CITED
(1) Bell, &F., I. AXAL. C m x . 22, 1005 (1950). (2) Epstein, 31. B., Willingham, C. B , Mair, B. J., Rossini, F. D., Zbid., 28, 1924 (1956). (3) Glasgow, A. R., Jr., Willingham, C. B., Rossini, F. D., J . Research Sat2. Bur. Standards 44, 141 (1'350). (4) Leslie, It. T., Zbid., 22, 153 (1939). (5) hlarschner, It. F., Burney, D. E., Znd. E7~g.Chem. 44, 1406 (1952). (6) Rossini, F. D., "Selected Values of Properties of Hydrocarbons aiid Related Compounds," Am. Petroleum Inst. Reseaich Project 44, Carnenie Institute ot Technology, .,. Pittsbkgh, Pa. ( 7 ) Rossini, F. D., Nair, B. J., Streiff, 1. J.. "Hvdrocarboris in I'etroleuni," Reinhoid, S e w Tork, 1953. (8) Willingham, C. B., liossini, F. D., J . Research .Vatl. Biir. Stnndards 3, 15 (1946). RECEIVEDfor review April 20, 1956. Accepted November 13, 1956. This report was prepared as part of the work of the American Petroleum Institute Research Project 6 in the Petioleum Research Laboratory at the Carnegie Institute of Technology. Part of the work was completed a t the Sational I3uie:iu of Standaids prior to July 1 , 1950.
