Mass Spectra of Some Organic Compounds R. H. ROBERTS
AND
S. E. J. JOHNSEN, Monsanto Chemical Company, Texas C i t y , Texas
Mass spectra on 53 organic compounds are presented as an aid to investigators in the field of analytical mass spectrometry.
B
EFORE any known multicomponent mixture can be quanti-
tatively analyzed by the mass spectrometer, it is imperative that the mass spectrum (or electronic dissociation pattern) of each of the pure components be accurately known. The spectrograms given here are presented with the intention of aiding other investigators in the field to predict the feasibility of the analysis of mistures of any of the compounds whose spectra are tabulated. I t is not to be inferred that these dissociation patterns are rigidly reproducible and fixed for a given molecule in any mass spectrometer, but rather that they are approximate descriptions of dissociation patterns which will vary somewhat from instrument to instrument. The salient features of all mass spectra are observed with nearly all analytical mass spectrometers when operated under the same conditions. FACTORS AFFECTING DISSOCIATION PATTERNS
A great deal of work has been done in the field of ionization by electron impact with a view to understanding the processes and mechanisms giving rise to mass spectra. Smyth (4) has reviewed the field up to 1931. Hipple (2) has published a short bibliography covering the work up to 1941. This bibliography is not complete but provides a list of the substances that have been studied recently with the mass spectrometer, so that the earlier work can be traced. Washburn and eo-workers (5)’have discussed correlations between the structures of paraffinic hydrocarbons and their mass spectra and have shown that, in some rases, isomeric mixtures of the paraffins can be resolved because of sufficiently different dissociation patterns. ’ They also discuss briefly some oxygen-containing compounds. A great many factors affect the structure of the mass spectrum of a givcn pure compound in a mass spectrometer. The totality of these effects is generally not large enough to distort the major characteristics of any pattern but it is large enough to warrant a weekly (or sometimes daily) rerun of the spectrum during the course of accurate quantitative work. It is of primary importance that the ratio of any two ion currents (peaks) in any spectrum does not vary as a function of the individual peaks. If this is not the case, secondary effects are occurring in the ionization chamber or in the tube itself and quantitative analyses of mixtures cannot be easily made. All modern analytical mass spectrometers are designed to operate a t such low pressures in the ion source and analyzer section that the probability of occurrence of secondary effects is negligibly small. The temperature of the ion source affects the mass spectrum. Relative to the parent ion, some peaks increase, others decrease when the ion source temperature is raised. Fox and Hipple ( I ) have published some quantitative data on the variation of mass spectra with temperature. They studied n- and isobutane and 2,2,3-trimethylpentane. From their data one finds temperature effects varying from -3.3% per 1O C. for mass 114 of 2,2,3-trimethylpentane through 0.0 for some peaks in isobutane to positive values in some cases. This thermal effect is large enough to warrant operating the whole ion source a t some constant, controlled, elevated temperature which is usually chosen a few degrees above the normal temperature attained by the ion source due to heat from the electron source filament. The constancy of electron energy is a factor to be considered. 690
However, this effect is usually small if the electron energy is maintained between 50 and 80 volts, as the ionization efficiency curves for nearly all ions studied so far are quite flat in this region. The electron current density in the ion source used in this work was so low that probably no secondary effects from this cause were present. There are transient effects such as field interactions in the ion source. These can perhaps be best illustrated by the fact that the dissociation pattern obtained a t one value of H and V (magnetic field strength and ion accelerating potential, respectively) differs slightly from that obtained a t other values of H and V. For analytical purposes this latter effect is of little or no consequence; the fields are varied in the same way for analysis as for calibration prior to the analysis. This variation of fields is important only in so far as comparison of mass spectra from different instruments is concerned-that is to say, the mass spectra of benzene obtained from two 90” sectoredfield instruments will not be identical any more than that obtained from a 180’ instrument compared to a sectored-field instrument. These differcnces are rarely, if ever, large enough to destroy the principal characteristics of any dissociation pattern. RELATIVE IONIZATION EFFICIENCIES
The relative ionization efficiency (RIE) may be defined as the number of parent ions generated per molecule per electron for the molecule concerned, to that number for the reference compound under the same conditions. For example, the relative ionization efficiency of compound a relative to compound b may be calculated from the, so-called, pressure sensitivities of the parent ions of a and b. A fundamental relation in mass spectrometry states that any peak in any mass spectrum must vary in strict linear proportion to the partial pressure of the compound a t hand, so that m,’ = Apa
where m,+is the intensity of the ion current for the parent ion of molecule a, p, is the partial pressure of a measured a t any convenient point in the entering system, and A is a constant of proportionality usually called the “sensitivity factor.” The same equation applies for the parent ion of the reference compound. Now, by dividing the first equation by the second, one finds,
where A / B is now the relative ionization efficiency of a referred to b. The relative ionization efficiency is ambiguous unless it is explicitly stated which ions of the two molecules are being related. In the discussion to follow, only the parent ions are used in the relative ionization efficiency values. The reference compound was arbitrarily chosen to be n-butane (parent ion 58). The conditions under which these constants were obtained are described fully in a later section. ,411 the relative ionization efficiency values given in Table I were obtained with the ion source and tube operating at 235” C. These constants are found t o vary from day to day and are different from instrument to instrument; hoivever, a series of relative ionization efficiency values from any instrument should be consistent among themselves.
V O L U M E 20, NO. 8, A U G U S T 1 9 4 8
691
On most mass spectrometers, these values rarely change more than 10% per month. I t is difficult t o place a figure of accuracy on the constants in Table I but i t can be safely assumed that the data are valid to, a t best, two significant figures. Some interesting relations are apparent in the data of Table I. If one writes the relative ionization efficiency constants in order for a homologous series of compounds, it is seen that there is a steady decline in the values, from the lowest member of the series to higher members. Table I s h o m this up only through 12butane for the normal paraffin series. This same variation appears to hold for the mono-olefins. I t appears to be true for the series benzene, toluene, ethylbenzene, n- or isopropylbenzene, etc. Another obvious relation is that between an olefinic compound and its corresponding saturated molecule. The relative ionization efficiency for the olefin is always the greater. This can be seen in the following pairs: Ethane Propane n-Butane Ethylbenzene Isopropylbenzene
1.8 1.5 1.0 5 4 4.6
Ethene Propene 2-Bu tene Styrene Isopropenylbenaene
7.5 3.1 3.4 11.3 6.8
When more data become available, it may be possible to find useful relations of the relative ionization efficiency among groups of isomers, thereby presenting a possibility of identifying a compound by means of its relative ionization efficiency. A future paper in this series will discuss this possibility further. SOURCES AND PURITIES OF COMPOUNDS
The purities of the compounds used to obtain these spectra n-ere only as high as the accuracy of the work warranted. Rather than discuss each compound in detail, the estimated purity is given a t the top of each pattern table. In those cases in which isomers could exist, and no statement is made to the contrary, it is t o be understood that the compound is a mixture of isomers. In these cases the purity figure indicates the quantity of materials not isomeric with the major component. I n some cases, where the impurities were known, the mass spectrum was corrected by subtracting the contributions of the foreign materials, so that even though the impurity was as large as loyo,the spectrum repre-
Table I.
Relative Ionization Efficiencies of Some Hydrocarbons Referred to n-Butane Parent Ion RIE
Compound Hydrogen hlnthane
1.9 6.3 1.8 1.5
1 .oo
0.24 0.00 7.5 3.1 3.4 3.9 2.3 4.1 1.4 5.6 2.5 13.6 6.9 5.4 6.7 4.6
Ethene Propene Butene-2 1,a-Butadiene 2-Methyl-l,3-butadiene 1,4-CycIopentadiene Methylc yclopentane Cyclohexane Methylcyclohexane Benzene Toluene Ethylbenzene o-Xylene Isopropylbenzene Methylethylbenzenes Diethylbenzenes Styrene Isopropenylbenzene
4.8
4.2 11.3 6.8
Table 11. Instrument Conditions 142 f 3 Resolving power 75.0 volts Electron energy 9 . 5 uamperes Electron current” Total electron current 21 .O ramperes Ion accelerating voltage 600 0 volts (fixed) Variable Main magnet field 5 . 0 volts “Draw-out potential” Ion p a t h deflection 900 5 . 0 inches Analyzer radius 235 floc. Ion source temperature 23513oc. Over-all tube temperature a Only focused electrons responsible for positive ion formation,
sents the compound a t a purity of very nearly 100%. l17hereno purity is given, it is understood that the purity was adequate for the problem in vhich the sample a-as used, which in most cases was bettcr than 90%. .is an example, n-hexane was purchased as “technical grade” and found to be too impure for use as received. ; inarrow boiling (0.5’ C.) cut, taken during a 30-plate fractionation of this material, was further fractionated azeotrop ically through a 60-plate column t o give the n-hesane that Fas used here. In all those cases where the purchased material was found to be inadequate, it was first purified by appropriate methods.
715
I I
ETHYLBENZENE
(147
TABLES OF MASS SPECTRA
All the patterns given were obtained under the same operating conditions. These conditions and some of the constants of the mass spectrometer used in this work are listed in Table 11. All the dissociation patterns presented here were originally obtained on a Leeds & Northrup Speedomas Type A strip chart recorder. The recorder and associated mass spectrometer were made by the Westinghouse Electric Corporation and have been described elsewhere (9, 3). Although the recording mechanism has been discussed previously (g), the recorder operation is described in order to clarify the salient features of the mass spectra presented here.
91
78
Figure 1. Mass Spectra of Ethylbenzene
As the recorder preamplifier receives a signal from the electrometer circuit due to positive ion current, the Speedomax pen moves up scale toward higher chart numbers. In order to record a
A N A L Y T I C A L CHEMISTRY
692 __--
Table 111. JIass Spectra Index Compound Parattins Methane Ethane Propane n-Butane Isohutane n-Hexane n-Heptane 2.2-Dimethylpentane n-Octane 2.2,4-Trimethylpentane n-Decane Olefins Ethene Propene %Butene 1-Pentene 2-Pentene 1-Octene 2-Octene Diolefins 1,3-Butadiene 1,3-Pentadiene Z-hlethyl-1,3-butadieiir Cyclo-olefins 1.4-Cyolopentadiene Cyclohexene 4-Ethenyloyclohexene- 1 d-Limonene Saphthenes Cycloyentane hlethylcyclopentane Cyclohexane Methylcyclohexane Ethylcyclohexane Aromatics Benzene To1u en e Ethynylbenzenp Styrene Ethylhenzene o-Xylene Isopropenylbenhene Isopropylbenaene Methylethylbenzene 1.3,5-Trimethylbenzene 1-Ethvl-4-ethenvlbenzrne o-Diet"hylbenzeie n-Butylbenzene l-Rlethyl-4-isoproprihpnlr ,ne Oxygen compoundMethanol Ethanol Dimethyl ketone Diethyl ether Ethyl acetate Sulfur compounds Carbon bisulfide Thiophene Piitrogen compounds Pyridine Chlorine compounds Carbon tetrachloride
Parent Mass 16 30 44 58 58 86 100 100 114 114 142
28 42 56
Section of Table IV 1 2 3
? 6 7 8 9
10 11
112 112
12 13 14 15 16 17 18
54 68 68
19 21 20
66 82 108 136
22 23 24 25
84 84 98 110
io
26 27 28 29 30
78 92 102 104 106 106 118 120 120 120 132 134 134 134
31 32 33 34 35 36 37 88 39 40 41 49 43 44
39 46
45
56
io
38
46 4 i
\vould pxobably othernise miss because of the time lost in going up scale and dropping back after shunting. After scanning the peak, the pen drops back toward the base line and n-hen it crosses the tenth chart division, the shunting mechanism ic cut out by a lower limit switch, after n-hich the recordei proceeds at normal sensitivity. The chart drive is linked mechanically to the niain magnet ~ ~ 1 trol diive, so that in this case the mass scale is scanned by varying the magnetic field while maintaining the ion accelerating voltagl fixed a t 600 volts. The precise relation betxeen chart reading and voltage developed across the electrometer grid resistor I ? easily obtained by inserting signals from a Type K potentiometci into the ground side of the grid resistor. When the recorder ha. once been calibrated in this way, all chart readings may be coilverted to millivolts by reference to the calibration table.
The chart given here, ethylbenzene, was redrawn exactly as t,iic* recbrder presented it and is illustrated in Figure 1. The irregnlarities due to the factor-of-ten shunt,can he seen a t the 91 peak i i i the ethylbenzene spectrum. Experience demonetratrcl in thts course of this work that tlrv dissociation patterns of o-, m-,and p-dicAthylhenzene and o-, t n - , and p-sylcne were so very much alike that no resolution of the. isomcw in either group could be made. For this reason only on? isomer spectrum for each group is given here. As mentionr~l above, some analyses of isomeric m i x t u i ~ sof paraffins have berail mail(,, so it appears that larger differences in dissociation patterns of paraffin isomers are to hr expected than for aromatics. .In index to Table I V is given in Table 111. The tahle of mass spectra is largely wlf-explanatory ; horvev6.r. romc clarification may be necessary. .I11 peak ratios given arc. espressed in terms of a parent ion peak height of 100 unik. Iii those cases where the parent ion is absrnt (as in 2,2,4-trimethylpentane) or where the term "parent ion'' can be ambiguous, sonic' other ion is chosen as a reference. This is always noted clearly. to avoid confusion. Occasionall! , base line irregularities, smeareil peaks, and shoulders on peaks are observed. For x a n t of a bettvr name, these are all called metastable ions here, even though sonit' ]nay not. actually be due to metastable ions. An attempt habeen made in Table IV to report these peculiarities whenever they are observed. Three significant figures are always reported. as the data originally obtained gt~nr~ra11~warranted this accurac? . This is not nieant to convey the impression that these same value.> can he exactly reproduced hy other workws, for reasons outlincvl
74 88
48
76 84
50 51
79
52
ACKNOWLEDGMENT
152
53
Tlir~authors wish to thank J. A\, Perry for his assistance in the preparation of the tables and to acknoir ledge gratefully the encouragement given hi- H . E. Morris during the course of this
49
:rhore.
n-01
20,000-iold raiige of 1011 currents with the same peiccntagr error for all values, the signal entering the recorder is attenuated logarithmicallv by the recording mechanisin (pen drive gears), The attenuation is, of course, not strictly logarithmic but linear from the chart 0 to 10 divisions and approximately logarithmic above this. An additional shunting feature is also used. As the pen responds t o a large ion current, it moves up scale until i t trips a limit switch at about 96 divisiong. This limit switch then immediately shunts the incoming signal by a factor of 10. .It the same time that this switch shunts the signal, the whole mass scale is set back slightlv to allow the pen to scan the peak top. which it
1 -
k. LITERATURE CITED
(1) Fox, 11. E.,and Hipple, J. A., J . Chem. Phys., 15,208 (1947). (2) Hipple, J. A., J . Applied Phys., 13,551 (1942). (3) Hipple, J. A , , Grove, D. J., and Hickam, W. M.,Proc. .l-otl. Electronics Conf., 1,322 (1944). (4) Smyth, H.D.,Rev. Modern Phys., 3,347 (1931). (5) Washburn, H. W., Wiley, H. F., Rock, S. M., and Berry. C.E . ISD. E N G . C H E M . , AN.4L. ED..17,74 (1945). R E C E I V E DSeptember 19, 1947.
Illass spectra data on 53 conipounds are found in Table lV, pages 693 to 699.1
V O L U M E 20, NO. 8, A U G U S T 1 9 4 8
Table IV. Mass Peak Ratio No. 1. w e t h a n e Source, Phillips. Purit? , 95.0. RIE, 6.3 16 100.0 15 80.1 14 8.28 13 2.90 0.47 12
Mass Spectra of Organic Compounds
Mass Peak Ratio No. 5. Isobutane Source, Phillips. PuiitZ, 99.88. RIE, 0.24 5SR 100.0 57 129,
66
5.86 7.59 1.14 7.97 1.57 14.2 22.8 3.99 139 4100. 1270. 1430. 78.1 494 81.7 34.2 0.66 1 .:34 194, 63.2
JJ
34 53 52 51
00 49 44
No. 2. Ethane Source, Phillips. Puritx, 99.0R I C , 1.8 30 I 100.0 29 84.5 28 438. 27 11.6 2G 87.0 25 1.18 24 0.77 15 0.83 14.5 1.12 14 .i .99 1I: 0.37
693
43 42 41 40 39h 38 37 36 30 29
28 2i
,26 .-
-
Mass Source, unknown. 100'1 99 98 97 88 87 86 85 84 83 82 80 79 78 72 71
io
69 68 67 66 65 03
(ii., 4,;. 2
'25
1.97 1.12
18 15 14
4 , ,;:I 41.G 2 88
-2.J
Peak Ratio
No. 8. 2,Z-Dimethylpentane
58
Purity, 95.0 100 0 14.8 140.
6.06 3.84 111. 382. 1000. 278. 19.9 21.2 21.2 96.8 33.4 31.0 603. 928. 864 81.3 82.1 8.20 23.3 13.3 72.3 1070. 3490. 1280. 137. 6.5.2 42.8 86.9 60.8
3i 30
__
.I.>
54 .5:3 32 31
;10
9.62
49 44 48 4'2 41 40
No. 6. n-Hexane S o i ~ r c e Phillips. ,
No. 3. Propane +iirce. Phillips.. Purity. 99.9 R I E , 1.3 44a 100.0 43 115. 42 22.2 41 57.4 40 8.05 39 64.2 38 19.2 37 10.6 36 1.91 30 7.51 29 397. 28 232. 27 104. 26 22.7 25 0.60 20.5 0.33 20 1 86 19.5 0.79 191.68 18 0.79 15 0.41 14 0.70
86"
ti d
84 72 71 70 69 fl8
67
58 .57 *
;; 54 53
52 51 50 44
43 42 41 40 39 38 37
36
30 29 28 27 26
No. 4. n-Butam 'ource,
Phillips.
55
54 B3 52 51 50 49
44 43 42 41 40
391, 38
37 36 30 29 28 26 25.5 25 18 15 14
100.0 18.2 2.56 3.62 0.41 2.23 0.66 3.72 5.03 1.10 26.7 782 99.0 220. 6.25 75.9 9.75 2.31 3.08 2.88 25.0 221. 25,5 0.84 0.66 2.15 3.89 0.43
39.3 39 :3 8
87
23.8 3 36 28.1 866 273, 743, 64.3
86
30 "9 28 27 2G
11.5 2.20 6.77 4.96
16.3 474, 237, 429. 16.fi
94.5 7.45 5.00 1.52 7.25 282, 44.6 157. 12.2 2.86 7.28
No. 7. n-Heptane Source, Phillips. Purity, 99.0 100" 100.0 85 8.45 72 12.0 71 X 33 . 70 1.30. 69 1.86 .5 8 7.80 .5 7 324, 3- 6_ 179. nd ti2.2 54 0.74 33 ,3.42 51 1.70 44 !0.6 43 56 6 42 133. 41 281, 40 6.02 39 70.3 38 1.99 36 2.49 30 1.99 29 192. 28 24.7 27 116. 26 3.77
No. 9. n-Octane Source, Eastman. Puiity, Eastman grade 114" 100.0 86 35.7 85 344. 84 ii3. 83 5.03 72 21.0 71 398. 70 200. 69 22.7 67 3.59 fi5 2.00 64-624 10.0 58 y . 3 57 37.8
.
;; 54 33
.j1
.50 43 -12 41 40
39 30 29 28 27 "fi
b e
d
% .5 2
51 50 49 42 40 39.5 39 :38.5 38 37,3
37 36 35
33'J
30 29
28 27 ?I:
698 R2 0
36.4 4.96
Purity, 99.78.
RIE, 1.00
58a p7 06
18c 13
Puritv. tt.vhnibal 100 0 4.90 9.12 3.13 42.5 9 70 19.1 1.40 2.38 30.4 713. 392
88.1 2450. 1280. 2:390, 152. 12.1
Mnss Peak Ratio No. 10. 2,2,4-Trimethylpentane Source, Phillips. Purity, 99 0. R I E , 0.00 100 26.5 83 2.90 0.26 80 72 0.18 71 4.44 1.07 70 69 2.01 68 0.35 67 1.73 66 0.22 0.58 24.1 57 553. 3A 173. .5 5 16.3 ,i4 0.91 . 8i 4,2,5
Keierence peak Metastahle -39.2. M a y be H.O+. .\Ieta-tahle (?).
"8
146. 8.04 18.0 5.97 1.64 bl.1 1j . 5 , 199.
46.7 90.8
7.84
318. 57.5 20.5. 14.0
0.63 1.92 0 92 0 44 4.02 100 0
7.04 0.82 110. 1.27 6.19
0.44 26.5 1.65 1.41 0.49 1.63 49.4 6.34 27.5 0.96
No. 11. n-Decane Source, Eastman. Purity, Eastman grade 142" 100.0 118 16.9 117 13.0 115 3.98 114 4.94 113 59.2 112 26.8 101 3.98 100 9.76 9B 94.5 98 67.1 97 :3.49 90 3.93 85 84 83 82 81 77 76 71
io
69 68 67 66 64 62
57 d6 B5
28.9 411. 132.
'2.0. - . JI) 6.24
3. ,54 30.8 587, 213. 66.4 8.22 7.40 3.25 2.05
64.7 1470. 272. 194.
34 . 3i . 2i .5 1 50 49 14 43 42 41 40
16.2 22.9 3.49 9.52 3.93 .50 6 1540. 199. 521, 21.7
39 38 36 32d 30 29 28 27 26
122. 4.31 2 00 5.54 9.59 340. 56.1 216. 15.4
ANALYTICAL CHEMISTRY
694
TableIV. R :ass Spectra of Organic Compounds (Continued) Mass Peak Ratio No. 12. Ethene Source, Phillips. Purity, 99.8. RIE, 7.5 28a 27 26 25 24 15 14 13.5 13 12
Peak Ratio No. 15. 1-Pentene Source, Phillips. Purity, 96.0 Mass
100.0 5.36 1.37 4.60 1.45 1.30 1.15 5.05 8.49 173. 3.49 13.4 1.45 4.80
70a 69 68 67 65 64 63 56 55 54 53 52 51 50
100.0 57.2 49.9 7.79 1.97 0.06 1.28 0.09 0.27 0.14
4.00 0.46 15.3 227. 108. 16.5 71.6 8.24 3.59 0.70 2.40 0.62 56.4 9.37 51.4 7.04
No. 13. Propene Source, Phillips. Purity, 99.2. RIE, 3.1 42a 41 40 39 38 37 36 29 28 27 26 25 24 20.5 20 19.5 19 18 15 14 13 12
Source,
100.0 164. 42.0 93.0 25.1 16.9 4.3 0.43 2.27 46.3 9.86 0.67 0.12 0.36 2.60 1.59 4.17 0.75 1.88 0.59 0.21 0.15
No. 14. 2-Butene Phillips. Purity, RIE, 3.4
'
100.0 41.1 7.40 15.9 2.91 10.8 12.7 3.50 0.26 0.11 0.21 6.75 199. 11.8
39 38 37 36 30 29 28 27.5 27 26.5 26 25.5 25 18 15 14 13 12
58.9 7.17 4.00 0.73 0.45 29.9 46.9 0.17 38.6 0.18 16.2 2.65 1.48 0.33 1.28 0.15 0 06 0.04
1125 97 85 84 83 82 81 79 77 72 71 70 69 68 67 66 65 64 57 56
100.0 20.5 10.5 130. 205. 32.7 4.01 3.29 4.26 3.29 77.5 553. 283. 33.3 34.4 3.53 6.62 3.74 3.04 119.
..
572. 615. 55.5 48.7 6.62 15.2 7.12 26.4 674. 467. 579. 34.9 216. 13.2 4.94 7.23 5.51 272. 54.9 211. 14.9
54 53 52 51 50 49 44 43 42 41 40 39 38 37 36 30 29 28 27 26
No, 16. 2-Pentene Source, Phillipa. Purity, 95.0+ 700 69 68 67 66 65 63 62 61 56 58 54 53 52 51 50 49 48 42 41 40 39 38 37 _. 36 35 33 32.5 32 31.5 31 30 29 28 27 26 25
96.2.
560 55 54 53 52 51 50 49 48 44 43 42 41 40
Mass Peak Ratio No. 17. 1-Octene Source, Connecticut Hard Rubber. Purity, 85.0f
a
b c
d
100.0 7.10 1.16 5.94 0.77 1.89 2.09 1.94 1.42 0.57 11.4 257. 6.46 19.8 2.41 6.42 5.25
.
Reference peak. Metastable -39.2. May be H*O+. Metastable (?). Unresolved shoulder.
0.96 7.10 102. 70.0 11.0 63.8 7.32 3.42 0.73 0.45 0.53 1.21 0.73 3.63 1.16 56.0 7.70 41.8 5.67 0.21
No. IS. 2-Octene Source, Eastman. Purity, Eastman grade 1120 97 93 92 86 85 84 83 82 80 78 72 71 70 69 68 67 66 65 63
100.0 5.38 1.22 3.15 2.10 28.5 72.4 9.13 3.15 2.09 2.61 1.56 17.4 172. 110. 15.3 18.0 1.98 4.00 1.67
58 57 56 55 54 53 52 51 50 44 43 42 41 40 39 38 37 36 30 29 28 27 26
4.68 69.0 203. 332. 27.8 26.1 3.69 8.75 4.78 3.29 68.6 142. 275. 13.9 85.0 4.77 2.85 1.33 3.38 140. 26.6 97.9 6.90
Peak Ratio Mass No. 19. 1,3-Butadiene . Source, Phillips. Purity, 99.8. RIE, 3.9 54 a 53 52 .~ 51 50 49 48 41 40 39 38 37 .. 36
100.0 70.0 11.6 24.3 26.2 8.26 1.05 0.08 3.16 101. 6.36 4.66 0.94
29 28 27 26.5 26 25.5 25 24 18
0.43 32.9 49.1 0.19 17.1 3.77 2.54 0.10 0.17 0.07 0.15 0.07
15
14 13
No. 20. 2-Methyl-l,3-butadiene Source, Phillips. Purity, 99.0. RIE, 2.3 68" 67 66 65 64 63 62 61 60 54 53 52 51 50
100.0 132. 11.2 12.2 1.00 5.01 4.07 2.95 0.61 1.17 4.01 88.9 5.66 12.1
49 48 47 42 41 40 39 38 37 36 35 33 32.5 32 31.5 31 29 28 27 26
9.29 2.15 0.19 0.55 19.6 33.9 35.9 53.3 9.21 4.59 0.49 0.42 0.42 0.61 0.48 3.06 2.19 3.23 24.0 3.16
No. 21. 1,3-Pentadiene Source, Koppers. Purity, 9O.Of 680 67 66 65 64 63 62 61 60 59 54 53 52 51 50 49 43 42 41 40 39 38 37 36 29 28 27 26 25
100.0 133, 11.8 18.0 1.25 7.21 5.60 4.13 0.93 2.45 3.02 79.5 5.01 8.50 6.31 1.40 2.17 24.0 46.4 38.8 65.8 11.2 5.60 0.59 8.18 7.04 26.8 4.84 0.40.
V O L U M E 20, NO. 8, A U G U S T 1 9 4 8
Table IV. hIass
Peak Ratio No. 22. 1,4-Cyclopentadiene Source, Koppers. Purity, 99.5 R I E , 4.1 66 5 100.0 65 47.9 64 4.75 63 8.78 62 6.33 61 4.70 60 1.11 51 2.59 50 1.81 49 0.79 48 0.13 41 1.07 40 28.3 39 31.8 38 8.82 37 4.70 36 0.68 33 1.82 32 1.80 31 5.02 28 0.31 27 2.48 26 1.18 25 0.23
No. 23. Cjclohexene Source, Eastman. Purity, Eastman grade 820 100.0 81 28.1 80 2.74 79 18.5 78 4.87 77 13.5 75 1.05 74 1.97 73 0.68 69 1.01 68 13.9 67 245. 66 5.72 65 9.61 63 2.97 62 1.10 61 0.54 56 3.67 55 54 53 52 51 50 49 43 42 41 40 39 5 39 38.5 38 37.5 37 36 29 28 27 26
14.2 176. 26.1 8.10 17.2 11.2 1.54 0.91 6.35 82.7 10.2 1.64 72.6 0.44 6.97 0.66 2.85 0.40 5.40 11.1 37.8 5.76
Mass Spectra of Organic Compounds (Continued) hlass
Reference peak.
b Metastable -42.2. d
M a y be HzO+. hIetastable (?).
Peak Ratio
No. 24. 4-Ethenylcyclohexene-1 Source, Daw. Purity, 95.0+ 108a 100,o 107 15.0 106 2.05 105 11.3 104 4.58 103 7.04 94 16.7 93 229. 92 13.9 91 111. 81 33.6 80 340. 79 687. 78 157. 77 173. 76 3.86 78 7.35 74 6.63 68 15.0 67 276, 66 386. 65 76.1 64 3.86 63 20.5. 62 6.46 61 1.57 55 57.8 54 1070. 53 119. 52.5 2.53 52 48.7 51 89.9 50 39.9 49 3.59 42 7.78 41 180. 40 31.5 39 333. 38 21.0 37 6 02 36 * 6 26 24 27.0 28 53.8 27 154. 26 16.0
Mass
Peak Ratio
No. 26. Cyclopentane Source, Phillips. 70a 69 68 67 66 65 64 63 62 61 60 58 57 56 55 54 53 52 51 50 49 44 43 42 b 41 40 39 38 37 36 30 29 28 27 26 25.5 25
Purity, 90.0+ 100 0 4.29 1.65 5.65 0.92 2 22 0 25 1.70 1 49 1.14 0 21 0.61 13 6 9.04 108 3 22 5 72 0 78 2.67 2.16 0.40 0.85 25.5 318. 86.0 18.3 51.76.m 2.84 0.36 0 21 16.0 6.68 28.8 4.72 0.50 0.43
Mass
Peak Ratio
No. 28. Cyclohexane Source, Eastman. Purity, Eastman grade. R I E . 5.6 840 100.0 83 6.06 a2 0.24 81 0.39 79 0.63 78 0.39 77 0.93 70 1.92 69 34.6 68 2.50 67 3.75 66 0.33 65 0.79 57 6.45 56 133, 55 44.7 54 53 52 51 50 44 43 42 41 40 39 38 37 36 30 29 28 27 26
7.37 4.50 1.26 2.89 1.93 0.84 16.1 34.2 68.1 5.34 21.5 2.23 0.87 0.77 0.43 9.46 10.5 17.1 1.93
No. 25. d-Limonene Source, Eastman. P u r i t y , Eastman 136a 121 120 118 117 116 115 114 108 107 106 105 104 103 102 95 94 93 92 91 90 89 88 80 79 78 77 76 75 69 68 67 66 6.5
64 63 62 61 57 54 53 52 51 50 49 43 42 ~~
41
0
695
40 39 38 37 36 20 28 27 26
-made
100.0 8.30 87.3 6.87 8.78 8.63 0.96 4.28 1.16 19.5 76.5 5 82 18.1 1.56 8.06 1.92 32.8 94.7 269. 81.4 57.8 1.70 2.37 9.18 50.4 49.7 105. 16.9 59.8 1.43 44.6 515. 234. 32.3 26.3 3.37 9.13 2.86 4.97 30.4 6.57 88.2 12.6 34.4 7.70 13.4 14.5 91.4 30.1 83.6 5.17 1.15 0.77 21.4 5.90 37.2 1.16
No. 27. Methylcyclopentane. Source, Phillips. Purity, Technicd. R I E , 1.4 84a 100.0 83 5.46 82 1.10 81 1.74 79 4.25 78 22.7 77 6.50 76 1.10 75 0.66 74 1.74 71 1.26 70 11.8 69 229, 68 25.9 67 17.0 66 L94 65 4.61 63 2.98 62 1.42 61 0.66 58 57 56 55 54 53 52 51 50 49 44 43 42 41 40 39.5 39 38 37.5 37 36 30 29 28 27 26
1.42 47.1 646, 153. 21.0 20.5 8.07 14.2 10.7 1.28 2.34 75 9 158. 335, 26.2 1.10 107. 11.8 ?.26 0.35 0.86 2.01 51.9 38.3 79.3 8.92
No. 29. Methylcyclohexane Source, Dow 980 97
..
7n
57 56 55
5 .4 .
53 52 51 50 44 43 42 41 40 39 38 37 36.5 36
.
Purity. 95.0+. R I E , 2.5 100.0 6.59 0.42 16.1 229. 33.9 3.18 1.62 0.52 1.78 2.69 50.1 51.5 20.4 10.2 0.87 1.97 0.87 0.41 10.4 66.1 177. 10.1 10.1 1.77 4.23 2.27 1.38 16.2 64.5 96.3 6.67 37.4 2.73 1.38 1.77 1.38 0.26 25.2 9.81 30.4 2.17
696
ANALYTICAL CHEMISTRY
Table IV. Mass Spectra of Organic Compounds (Continued) Mast. Peak Ratio No. 30. Ethylcyclohexane Source, Eastman. Purit) , Eastman grade 112" 111 85 84 83 82 81 80 79 78 77 71 70 69 68 67 66 65 63 61-59d 57 56 B5 54 53 52 51 50 44 43 42 41 40 39 38
6.65 56.5 377. 24.0 18.3 3.28 7.08 2.71 1.29 35.6 43.0 182. 9.11 57.5 2.99
37-36d 30 29 28 27
5.05 0.71 42.6 14.3 51.1 3.01
26
Mass Peak Ratio No. 32. Toluene Source, Monsanto. Purity, nitration grade. R I E . 6.9
76 75 74 67 66 65 64 63 62
0 31 0 70 0.13 0 80 16 9 1 03 9 57 3 31 0 93
53
0.43 4.04 11.4 6.70 0.31 0.19 4.55 1.99 7.40 0.20 0.55 0.13 1.27 0.93 0.76 17.3 3.58 0.83 0 61 0.34 1.58 0.28
::
50 49 46.5 46 45.5 45 44.5 44
43,s
43 41 40 39
38 37 36 28 27 26
Mass Peak Ratio No. 34. Styrene Source, Monsanto. P u r i t J , 99.8 R I E , 11.3
No. 35. Ethylbenzene Sourre, Momanto. Purity, 99.0+ R I E . 5.4
Mass Peak Ratio No. 36. a-Xylene Source, Eastman. Purity, Eastman grade R I E , 6.7
.
106° 105 104 103 102 101 99 98 97 96 95 93 92 91 90
100.0 42.4 5.50 10.4 2.30 0.79 0.26 0.60 0.76 0.26 0.19 0.52 13.4 170. 1.53
89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 70 69 68
3.15 0.28 0.58 0.58 0.5; 0.30 0.42 0.50 0.5; 1.05 11.9 11.6 20.1 1.58 1 82 4.00 0.44 0.21 0.25 0.44
e7
0.10 0.54 1.40 10.8 1.61 7.84 2.92 1.23 0.82 0.40 1.08 0.33 4.51 1.0d 10.2 1 53 20.7
66 65 64 63 62 61 60 56 55 54 53 52 51.5 .d1
No. 31. Source, Baker.
.so .j0
Benzene
Purity,
C.P.
49.5 49 48.5 48 45 44 43 42 41
RIE,
13.6 78a 77 76 75
74
73 64 63 62 53 52 51
50 49 40 39 5 39 38.5 38 37.5 37 3A 28 27 26
a b C
d
Reference peak. Metastable -39.2. hIay be HzOr. Metastable (?).
100.0 18.4 5.13 0.82 3.79 0.63 1.55 0.17 0.16 0.27 17.5 14.7 12.0 0.84 0.08
0.08 11.3 0.13 3.81 0.42 2.30 0.50 0.17 0.56 0.46
No. 33.
Ethynylbenzene
Source, Farrhan.
5
40
39 38 97 36
P u r i t J , 95.0f.
fi3 62 61 ;.:3 .5 2 . .j R2 51 6 .1 i
an
49 41
-to 39 38 37 36 28 27 26
7.96 1 26 0.16 1 .OO 0.26 9.30 0.64 29.9 9.19 0 R? 1 .0Tr
0.11 1.5.3 1 ,i 2 0.11 O.R.5
0.90 5.23 0.32
29 28
27 "6
0.30 7.06 0.26 0.88 0.41 0.24 1.21 0.30 2.8; 1.59 14.8 2.74 0.98 0.43 0.63
0.85 7.00 0 80
V O L U M E 20, NO. 8, A U G U S T 1 9 4 8
Table I V . Peak Ratio
llUsS
Mass Spectra of Organic Compounds (Continued) Mass
Purity. ! I . i . O - .
%III~V?,
RIE. 6.8
118'L
10u.u 71 .0 9 . 10 21.1
I17 116 I15 114
1.48
113 107 108
1.08 1.58 4.00 45,6 4.43 0.59 0.16 0.18 0.33
105 104
103 I02 101 100
91 90 89 88 87 86
85 84 78 77 i6 75 74 73 72
65 64 63
ti2 61 60 38 57.5 37 56.5
41
40 39 38 37 36 28 27 26
0.91
1.47 1.35
11.8
7.33 2.82 0.28 0.30 1.41 3.94 0.44 16.3 7.11 0.50 0.12 0.15 0.35 0.10 I .72 1.50 11.3 1.81 0.74 0.11 0.10 0.33 2.78 0 41
;tj
.,.,
;. 4
52 51
.io. 5
RO 49 48 45 44
43 42 41 40 39 38 37 36 29 28 27 26
Isopropylbenzene
Sotiice, Fenske.
Purity, 98.0.
RIE, 4.6
-,I)
4 i:!'
titi
0.45
64 63 62 60 8 .a7 .? 3I 52.5 J2 51.5 51 50
1,60
Purity. H X . 0 .
nw. 4.(i
65
17.9 l.4i 3.56 0.41 0.89 0.68 0.36 2.40 28.9 19.9 2.93 2.60 3.0i 0.07 0.15 0.47 5.01 0.97 6.33 2.67
66
81 80 79 78 77 76
Fenike.
5.94
1 . Oti
0.40 2 50 1.56 1.18 1.78 2.45 8.07 1.11 X6.7 9.13 8.78 0.50 16.4 1.11
0.29 0.80 1.19
10.1 0 24
No. 39. Methylethylbenzene
1.03
39.1 17.9 45.4
1.49
1.49 1 .R2
69 67 66 65
Purity, 98.0-t RIE, 4.8
donrce, llonsanto. 120" 119 118 117 116 115 107 106 105 104 103 102 101 93 Y2 91 YO 89 88 87 86
85 80 79 78 77 76 75 74 66 65 64 63 62 61 60 58 5 p8 07 5 d7 56 5 56
54
100.0 1.52 0.55 1.00 0.30 1.59 33.5 361. 13.4 28.2 2.95 1.08 17.6 1.18
Peak Kntiu 1,3,5-Trimethylbenzene Source. E : a ~ t t t i n n . Purity, t w h n i w grade 120" 100.0 119 26.5 118 1.72 117 4.47 116 L.53 115 4.09 107 0.91 106 13.9 105 156. 104 5,3ti 103 9.36 2.31 102 101 0.97 97 0.52 96 0.59 0.61 95 94 1.15 93 1.98 92 3.60 91 12.1 90 0.64 89 1.40 87 0.36 86 0.41 85 0.20 83 0.36 82 0.21 81 0.50 80 0.76 79 8.24 78 4.84 77 11.2 76 0.91 75 1.20 74 1.23 70 0.34 Alas$
No. 40.
0,48
Iii
NO. 38.
Peak Ratio
No. 38. (Conrd.)
No. 37. Isopropenylbenzene Jourrr. llonsanto.
697
53 .7 2 51 5 51 50.5 50 49 48
44 43 42 41
40 39 38 37 86 '?Q 28 27 2h
64
100.0 11.5
63 62 61 60 59.5 59 58.3 58 57.5 57 55 54 53 52.5 52 51.5
2.07 7.41 1.99 7.10 1.29 30.8 330. 8.17 17.8 3.66 1.51 2.27 10.1 32.6 1.51 4.24 0.30 0.80
51
50 43 42 41 40 39 38 37 29 28 27 26
0.80
0.33 1.60 23.0 9.89
30.7 1.99 2 25 2.03 0.25 1 .2!l 13.6 1.94 9.48 3.42 1.22 1.73 9.48 2.07 8.05 6.01 2.71 0.48 0.26 5.05 0.60 4,65 0.65 15.0 . a . 74 0.33 0.26 0.23 0.15 5.84 2.45 17.8 2.45 0.65
0.58 1.18 74.7 !>.a6 u 70
a b C
Reference peah. Metastable -39.2. M a 3 be H?O+.
d l l r t n ~ t a b l c( 1 ) .
0.45 0.66 0.71 4.88 0.93 3.86 1.42 0.52 0.82 0.78 4,l2 1,05 3.74 2.55 2.03 0.88 0.25 3.65 0.30 2.65 0.25 7.65 2.85 1.17 0.25 5.29 1.14 10.1
1.1Y 0.31 0.78 0.63 5.72 0.84
31as
Peak Ratio
No. 41. 1-Ethyl-4-ethenylbenzene Source, University of Illinois. Purity, 9O.Of 132" 100.0 9.38 131 1.97 130 129 8.60 6.10 128 127 3.06 126 0.70 0 94 120 2 65 119 24.1 118 117 23.8 13.8 116 115 38.1 1.37 106 11.9 105 104
103 102 101 92 91 90 89 88 87 86 79 78 77 76 75 74 65 64.5 64 63.5 63 62 5 62 61
60
58 57.5 57 53 52 51 50 5
50 49 48 41 40 39 38 37 36 29 28 27 26
5,oo
6.81 .5,39 1.64 2.18 28.1 1.OS 4.56 0.38 0.87 0.57 3.09 5.16 15.2 2.52 3.09 2.75 4.04
0.81 12.1 1.79 7.52 1.79 10.2 2.78 0.74 2.61 1.83 6.51 0.28 3.49 3.37 0.34 15.7 5.77 0.34 2.02 0.92 12.9 1.66 0.34 0.64 0.73 2.20 5.74 0.66
ANALYTICAL CHEMISTRY
698
Table IV. Mass
Peak Ratio
No. 42. Diethylbenzene Source, NACA. Purity, 99.0+. R I E , 4.2
134a 133 131 129 128 127 120 119 118 117 116 115 106 105 104 103 102 101 93 92 91 90 89 80 79 78 77 76 75 74 66 65 64 63 62 59 58.5 58 57.5 57 54 52 51 50 49 41 40 39 38 37 36 29 28 27 26
100.0 1.96 0.58 0.50 1.56 0.71 20.4 202. 6.43 32.0 6.93 19.9 19.0 201, 13.7 19.9 4.20 1.64 6.16 4.74 54.8 1.64 5.14 0.92 17.2 10.6 30.1 2.10 2.57 2.48 1.26 13.8 4.07 9.39 2.69 0.73 1.01 4.07 6.13 8.40 0.56 5.01 4.40 16.4 5.72 12.5 1.51 16.3 1.79 0.26 0.39 3.68 2.87 7.12 0.64
No. 43. n-Butylbenzene Source, Eastman. Purity, Eastman grade 100,o 4.33 4.65 2.89 1.27 4.41 4.14 38.8 5.27 7.73 2.12 0.87 0.44 1.70 1.27 1.01 0.51 15.4 207. 378. 4 48 6.14 0.67 0.51 0.51 4.80 58 1 34.4 3.65 1.34 11.4 21.6 20.6 2.00 2.05
Mass Spectra of Organic Compounds (Continued) Bfass
Peak Ratio
No. 43. (Contd.) Source, Eastman. Purity, Eastman grade 74 2.00 73 0.48 71 0.71 70 3.01 69 5.14 68 2.33 67 9.13 66 2.84 65 35.9 64 3.27 63 9.65 62 2.55 56 7.96 56 39.7 54 3.86 53 5.02 52 5.02 51 18.9 50 7.05 44 0.54 43 12.0 42 3.78 41 28.7 40 2.39 39 26.2 38 2.20 37 0.73 36 0.31 29 9.35 28 2.80 27 l5,2 26 0.87
.
Peak Ratio Mass No. 44. (Contd.) Source, Eastman. Purity, Eastman grade 1.37 0.66 14.4 1.33 13.4 1.24 0.17 0.24 0.76 1.33 6.46 0.37
No. 45.
Methanol
Source, Carbide. Purity, C.P.
No, 46.
No. 44.
I-Methyl-4-isopropylbenzene Source, Eastman. Purity, Eastman grade 134O 100.0 133 3.34 0.73 132 0.44 131 2.07 121 40.1 120 119 396. 9.19 118 34.1 117 116 6.84 115 18.4 1.09 107 8.75 106 6.89 105 9.44 104 2.37 103 0.65 102 0.21 97 0.31 96 1.51 95 0.31 94 5.61 93 4.48 92 39.2 91 1.16 90 3.28 89 0.54 83 0.31 82 0.84 81 0.21 80 5.05 79 4.23 78 13.3 77 0.84 76 1.16 75 74 69 68 67 66 65 64 63 62 61 59.5 59 58.5 58 57.5 57 56 25 54 53 52 51 50
0.96 0.52 0.72 0.99 2.26 12.3 2.66 5.80 1.62 0.16 1.16 0.72 4.14 4.90 5,26 1.81 0.36 2.07 0.16 3.12 2.26 8.18 3.12
Ethanol
Source, Carbide. 46a 45 44 43 42 41 32 31 30 29 28 27 26 25 19 18 17 16 15 14 13 12
No. 47.
15
a
b C
d e
Purity, C.P. 100.0 230. 17.6 44.6 14.5 4.34 41.3 526. 29.0 111. 54.2 82.7 28.8 4.38 14.5 4.16 9.96 1.69 36.5 14.4 4 18 0.86
Dimethylketone
Source, Carbide. 584 57 55 53 44 43 42 41 40 39 38 37 36 35 31 30 29 28 27 26 25 24 19 18 16 14 13 12
Purity, C.P. 100.0 2.81 0.86 1.08 0.72 6.35 275. 17.6 5.37 2.15 8.73 4.76 4.43 1.75 1.51 0.28 8.31 7.72 13.8 9.17 2.22 0 35 0 64 0.64 0.72 66.2 9.75 2.35 0.61
Reference peak. Metastable -39.2. M a y be HnO+. hletastable ( 1 ) . Metastable 28.8.
-
Mass Peak Ratio No. 48. Diethyl Ether Source, Mallinckrodt. Purity, 95.0+ 744 100.0 73 10.2 1.13 72 5.21 59 58 159. 57 0.80 56 0.88 46 0.70 5.54 45 44 132. 6.06 43 23.7 42 4 .63 41 16.2 40 0 .38 39 0.34 35 0 . 48 33 4.07 32 359. 31 6.85 30
No. 49.
Ethyl Acetate
Source, Baker. Purity, C.P. 88 1.76 87 31.1 86 1.66 73 0.95 72 29.4 70 2.46 69 59.7 61 2.43 60a 100.0 59 6.14 58 0.81 55d 2.43 45 44 43 42 41 40 35 31 30 29 28 27 26 25 19 18 17 16 15 14 13 12
No. 50.
2.72 104. 19.9 680. 35.1 3.06 0.85 8.54 4.25 107. 38.3 49.6 12.7 0.81 2.44 3.29 0.46 1.31 54.6 13.3 2.37 0.36
Carbon Bisulfide
Source, Baker. 80 79 785 77 76 66 64 59 46 45 44 39 38.5 38 36 34 33 32 28 27 25
Purity, C.P. 2.51 1.97 100.0 29.7 1120. 1.00 11.4 2.08 4.65 1.94 106. 6.72 1.93 76.2 0.53 3.94 0.75 77.9 9.97 0.33 0.64
V O L U M E 20, NO. 8, A U G U S T 1 9 4 8
Table IV. Peak Ratio Mass No. 51. Thiophene Source, Socony-Vacuum. Purity, C.P 0.16 87 4.47 86 5.47 85 100.0 84“ 6.33 83 2.54 82 3.81 81 0.56 80 0.16 77 1.76 75 0.32 70 0.32 69 6.63 68 0.53 67 0.53 66 2.76 59 2.26 58 60.6 57 9.91 ?S 1.10 DO 0.14 51 2.75 50 4.15 49 1.88 48 0.46 47 a
6
699
Mass Spectra of Organic Compounds (Continued) Mass Peak Ratio NO. 51. (Contd.) Source, Socony-Vacuum. Purity, C.P. 1.83 46 1.02 45 41.8 44 1.57 43 0.22 42 0.22 41.5 3.86 41 0.22 40.5 1.83 40 1.18 39.5 1.83 39 19.5 38 4.96 37 3.56 36 2.28 35 0.19 34 0.27 33 0.36 32 1.60 31 0.58 28 0.76 27 2.07 26 0.68 25 0.17 24
Reference peak. N o ionization a t parent mass.
Mass No. 52.
Peak Ratio Pyridine
Source, Eastman. Purity, Eastman grade
Mass
No. 53.
Peak Ratio
Carbon Tetrachlorideb
Source, Sharples. Purity, redistilled commercial 10.9 123 1.29 122 100.0 121a 3.98 120 306. 119 4.03 118 314. 117 7.29 86 1.40 85 43.3 84 2.06 83 66.6 82 1.87 76 1.57 71 2.60 69 3.59 60 10.6 59 58 10.8 16.4 48 0.75 47 50.8 46 43 2.79 0.44 42 1.12 41 1.93 40 4.37 38 9.84 37 11.9 36 28.8 35 21.8 28 ~~
Depolymerization of Butylene Polymers Analysis of Isomeric Octenes by the Mass Spectrometer F. G. CIAPETTA, S. J. MACUGA, AND L. N. LEUM, The Atlantic Refining Company, Philadelphia, Pa.
In a study of the catalytic depolymerization of butylene polymers over Attapulgus clay, several analyses of octene feed and products of the experiments were needed in order to determine the extent and the manner in which some of the original compounds were isomerized over the catalyst. The method employed consisted of hydrogenation to the corresponding paraffins, fractional distillation, and analysis of the fractions by means of the mass spectrometer. The analytical data are presented, and
I
h h study of the catalytic depolymerization of butylene poly-
mersin the presence of Attapulgus clay ( 3 ) ,leading to the development of a means of manufacturing pure isobutylene from “cold acid polymer,” certain chain isomerizations of the octenes were suspected as accompanying or preceding depolymerization. T o determine what changes took place and t o what extent, exhaustive analyses of both feed and liquid products of a few typical experimeiits were needed. This paper describes the method of analysis used and the results obtained on analyzing these complev niixtuie-. of hydrocarbons by means of the mass spectrometer, Direct analj sis of these mixtures as olefins was not possible, as the n e e w a r y calibrating compound3 were not available. If these pure materials had been available, there is also considerable doubt as to ahether the unknoir-ns could have been analyzed nith the desired degree of accuracy in view of the difficulties expeiienced in mass spectrometric analysis of olefins of lon er molecular weight. By hydrogenating the olefins to the coriesponding paraffins the octanes can be analyzed nith good accuiacy ( 2 ) , provltling the number of isomers in any particular mixture analyzed IS not overly
the method of arriving at the various carbon structure isomerizations occurring in two typical experiments employing cold acid polymer and a codimer made o v e r U. 0. P. phosphoric acid catalyst, respectively, is described in detail. Summaries of the over-all reactions that occurred with these two stocks gave mole balances of 99.4 and 95.3Yo of the compounds charged and accounted for as undergoing depolymerization or as being isomerized into other octenes.
large. This mcthod does not show the composition of the mixture as far as position of the double bond in the various isomers is concerned, but it does indicate the carbon structure of the isomers, which was the main issue of this investigation. EXPERIMENTAL
The depolymerization procedure, apparatus, Attapulgus clay catalyst, and hydrocarbon feeds are described elsewhere ( 3 ) . The specific hydrocarbons used for the experiments reported here were a fraction of cold acid polymer obtained from the Neches Butane Products Company, Port Seches, Tex., boiling between 101O and 103’ C., which is essentially diisobutj-lene, and a 95” to 119’ C. fraction of a pol)-nicr formed in the presence of a Universal Oil Products Company phosphoric acid catalyst. In the preparation of this polymer the ratio of n-butylene to isobutylene consumed in forming the polymer was 0.7. Gas Analysis. The gaseous products were analyzed in a Consolidated Engineering Corporation mass spectrometer. Because the isobutylene contcnt of thc gas was very high the modified technique reported by llelpoldcr and Brown ( 4 ) was used. At the concentration of isobutylene found in the present work the accuracy of its determination by this technique is within *0.37,.
