phenyl isocyanate. Tertiary amines do not interfere; neither do carbonyl compound>, carboxylic acids. or acetals. Most aroinatic hydroxyl compounds do not react with phenyl isocyanate, or react with a rate less than that of tertiary butanol-e.g., the rate of reaction between 2.6-di-tert-butyl-pcresol and phenyl isocyanate is allproximately 5 x liter mole-’ minute-‘ under the reaction conditions, about three tinies slower than the tert-butanol reaction.
LITERATURE CITED
(1) Baker, J. W., Gaunt, J. J., J . Chem. SOC.1949, p. 9. (2) Burkus, J. J., J . Org. C h e m 26, 779
(1961). (3) Crummett, mi. B., AKAL. CHEM.34, 1147 (1962). (4) Hanna, J. G., Siggia, S., J . Polymer Sci. 56. 297 (1962). (5) Hendrickson, J.’G., ANAL.CHEM.36, 127 (1964). (6) PIIark, H. B., Papa, L. J., Reilley, C. N., in “Advances in Analytical Chemistry and Instrumentation,” C. K . Reilley, ed., 1-01, 2 , pp. 255-385,
W’iley, Kex York, 1963. 17) Paaa. L. J.. Mark. H. B.. Reillev. ” , C. 9.. ANAL.CHEM.34. 1513’11962). ( 8 ) Reed, D. H., Critchfield,’ F. E., Elder, D. K., Ibzd., 35, 571 (1963). (9) Reilley, C. N., Papa, L. J., Ibzd., 34 , 801 (1962). (10) Schmalz, E. O., Geiseler, G., Z. Anal. Chem. 190, 222 (1962). (11) Siggia, S., Hanna, J. G., I b i d . , 33, 896 11961). (12) Smith, H. A., J . i l p p l . P o l y n w Sci. 7, 85 (1963). RECEIVEDfor review July 10, 1964. Accepted August 14, 1964.
Identification of 2-QuinoIones in a California Crude Oil EDWARD C. COPELIN Union Oil Co. of California, Union Research Center, P.
b The discovery and identification of 2-quinolones in a California crude oil are described. This is the first time that 2-quinolones have been reported in any crude oil. Infrared spectra of heavy gas oils vacuum distilled from a few crude oils sampled from wells in the Ventura Basin of California showed a unique spectral absorption band a t 6.07 microns. From the particular gas oil showing the most intense 6.07-micron band, a fraction containing the substances causing this band was isolated by chemical and chromatographic methods. This fraction was analyzed by elemental analysis, nonaqueous titration, nuclear magnetic resonance and mass spectrometry, and infrared and ultraviolet spectrophotometry. The 6.07-micron band was identified as being predominantly caused by the amide carbonyl group of 2-quinolones. They of the gas oil comprise 0.4 weight and 0.05 weight of the crude oil.
7 0
EXPERIMENTAL
The particular crude oil whose heavy gas oil showed the most intense 6.07niicron band was selected for study. Crude oil obtained directly from the well was dewatered by centrifuging. Preliminary small scale distillation studies showed that the 6.07-micron band first appeared in the infrared spectra of fractions boilingabove 300’ C. This suggested that the compounds re-
0
ANALYTICAL CHEMISTRY
sponsible for the band would be rather large molecules. About 250 ml. of heavy gas oil with a boiling range between 343” and 454’ C. were vacuum distilled from the crude oil by an AST;\2 method ( 2 ) . Thii cut repreqented 14.2 weight % of the crude oil. Figure 1 shows separation steps and analytical data. Sonaqueous extracts or solutions were dried over potassium hydroxide pellets whenever possible. Removal of solvents \\as carried out below 100’ C. under nitrogen a t about 0.5 atni. Hydrogen Chloride Gas Treatment of Gas Oil. Ai 100.0-gram portion of the heavy gas oil was denaxed with 750 ml. of la-pentane at 0’ C. The brown, n axy precipitate weighed 0.52 gram. D r y hydrogen chloride gas was bubbled through the pentane filtrate for 45 minutes. After removing the supernatant liquid by KEY
0.301 % N
7 0
and separation techniques are making it possible to better understand the chemistry of the nonbasic nitrogen compounds in petroleum. The definition of nonbasic nitrogen compounds proposed by Richter and coworkers (10) as those nitrogen compounds having a pK, 5 2 is used in this paper. dmides constitute one of t8hesenitrogen types currently being studied. Bezinger, hbdurakhainanov, and Gal’pern (3) reported the presence of 3,4-dihydro-2quinolones in a Russian crude oil, while Jewel1 and Hartung ( 6 ) described the identification of benz-2-quinolones in a heavy gas oil. I n both cases, there was no direct evidence of the amide functional group in the original stock, whereas the work reported here was per-
Brea, Calif.
formed to identify the cause of a band a t 6.07 microns in the infrared spectra of some heavy gas oils. This band was caused by the amide carbonyl functional group of 2-quinolones. The gas oils were mcuum distilled from crude oils sampled from wells located in the Ventura Basin of California.
W T X OF GAS OIL
n-PENTANE DEWAXING
WAX 0 . 5 2 X 10.31 Y. N IIR I4.1IXSI
1
I
BLACK OILY PRECIPITATE
ODERN AKALYTICAL METHODS
2274
0.Box 76,
I AQUEOUS HCI EXTRACTION INSOLUBLE I::LUB/ O . I:4*XBN} Z K EASES
-!IR
4 . 8 9 % EASES
I f ? = INFRARED ELEMENTAL U V . ULTRAVIOLET ANALYSES EN s BASIC L V M S LOWIONIZINO-VOLTAGE NITROGEH MASS SPECTROMETRY N A T NON-AQUEOUS TlTRATlON FOR N-H N M R . NUCLEAR MAGNETIC RESONANCE
-
-
I % RECOVERED BETWEEN STEPS
& I N S
Figure 1 .
100 83
100
100 104
79
Flow diagram and material balance of fractions separated from 343-454” C. gas oil
343 -4 5 4 ' C GAS OIL
1 1
cw
( M )
I
CHz
I
&SI
Figure 3. Comparison of infrared spectral absorption bands shown by fraction C with those exhibited by 2-quinolones
the fractions separated from it appear in Figure 1. Total nitrogen content was determined by either the Kjeldahl or the Dumas method, the latter being used on samples containing more than 1 weight ye nitrogen. I'otentiometric titration with pcrrhloric acid of samples dissolved in glacial acetic acid was used to measure their basic nitrogen contents. Total sulfur was determined by the peroside bomb method. Carbon and hydrogen were determined by micro combustion methods. The spectral data were obtained by conventional infrared, ultraviolet, nuclear magnetic resonance, and ion- ionizing voltage mass spectrometric techniques. Because the intent of this paper is to describe the isolation and identification of 2-quinolone.s, the compositional analysis of the other fractions is omitted, except to state that fraction B was a misture of carbazoles and benzcarbazoles. Fractions A, B, and C were titrated in pyridine with tetrabutylanimoniuni hydroxide. This system w-ill titrate the S-H functional group of carbazoles, benzcarbazoles, and 2-quinolones and will not titrate their S-alkyl derivatives. Fraction A contained no titratable material. Fraction TJ, the carbazole-benxcarbazole fraction, contained titratable material equivalent to 4.9 weight 7c nitrogen. Since the nitrogen in fraction I3 was found by to be 5.0 weight ye,, essentially all of the nitrogen appears to be present as S-H. .%bout 75% of the total nitrogen in fraction C: could be titrated, and if it is assumed that only 2-quinolones are present, then about 25Tc must contain Y-alkyl groups.
The fate of the remaining 177, nitrogen is presently unknown. The cause of the 217, loss of total sulfur in the elution chromatographic- >tell is likewise presently unknown. Separation of 2-Quinolones from Original Gas Oil. Infrared sptctrophotometry was used to trace the presence of 2-quinolones during the separation proces,s. Figure 2 cont'ains the infrared spectra of the original gas oil and some of the fractions separated from it. Those fractions not appearing in Figure 2 do not show the 6.07-micron band. The top two curves are spectra of 0.20-nim. thick films, while the bottoiii five curves are spectra of film. al)prosiniatcly 0.025 nini. thick. The absence of the 6.Oi-niicrr~nband in the spectrum of the residual gas oil fraction and its presence in the insoluble bases fraction shows that precipitation of 2-quinolones from a 1)rntane .wlution of the gas oil is efficient. similar result was obtained by chroniatogi,al>hing some of the original gas oil over aliimina. This demon.+trate+ that 2-quiiioloncwere not generattd by the hytlingzrn chloride gas treatnient. .ifter the ion exchange separation, a nc.gligiblc
ysis of Fraction C. The infrared spectrum of fraction ( ' rhon.n in Figure 3 agree:: u i t h infr:irrtl spc,ctra of 2-quinolones obtained in thi. labcira-
DISCUSSION
Material Balance of Fractions Separated from G a s Oil. T h e weight yo of material recovered after each separation step is included in Figure 1. Only 83Yc of t,he total nitrogen originally present in the gas oil was found in the was, residual gas oil, soluble bases, strong bases, and weak bases fract,ions.
shoulder at 7.7 microns indicate.. that there may he mnic I\--aliiyl-2-quinolonri present. The 25Yc of' noiititratable nitrogen in fraction C may at leaht in part be due to these compounds. VOL. 36, NO. 12, NOVEMBER 1964
2275
reference compound, LV-ethyl-2-quinolone. 13y this technique the average molecular weight of fraction C was 285, which' is in good agreement with the previous value of 304. The average molar absorptivity of 4-quinolones is about half that of 2-quinolones (8). If fraction C were assumed t,o be 4quinolones, then its average molecular weight would be about 150, which is much too low.
FRACTION C
Ultraviolet Spectrophotometric Analysis of Fraction C. The ultraviolet WAVELENGTH
IN MICRONS
,
Figure 4. Influence o f environment on N-H and C=O stretching bands in infrared spectra o f fraction C
The relative intensity of the 1 3 . 4 iiiicron C-H out-of-plane bending band comlmed to the other bands at 11.7 and 12.4 microns indicates that most of the 2-quinolones are unsubstituted on the benzene ring. The weak band at 14.7 microns appears to be typical of 2-quinolones but could not he correlated with any particular functional group. An unusual band shows u p at 8.95 microns. Tentatively, this has been assigned to the moderately intense C,=S stretching band of 2thioquinolones ( I Z ) , the sulfur analogs of 2-quinolones. The presence of 2thioquinolones may account for t,he 1.8 weight % sulfur found in fraction C. An additional problem in the identification of the molecular species causing the band a t 6.07 microns was that the infrared spectra of 2- and 4quinolones are practically identical (Y). Therefore it was necessary to detemiine how much of each was in fraction C . For this reason, infrared spectra of fraction C in solution were recorded and are shown in Figure 4. The S-H stretching band appears at' 3.14 microns for the film and a t 2.94 microns in chloroform solution. hccording to Katritzky and =Imbler (8), t1ii.s shift is typical of 2-quinolones. In contrast, I'rice and Killis (9) found 4-quinolones to exhibit a broad, weak S-H band, between 3 and 4 microns, which is not greatly influenced by environment. ,Inother criterion used in this work to diffc,rentiate between 2- and 4quinolonea was the comparison of aieragr molecular weights of fraction C determined by independent methods. Assuming one nitrogen atom per molecule. 4.6 weight % total nitrogen in fraction C is equivalent to an average molecbular weight of 304. The 6.07micron clarbonyl band of fraction C in rhloroforni shown in Figure 4 was integrated from 5.8 to 6.2 microns and cmniliared to the integrated absorbance of t h c amide carbonyl group in a 2276
ANALYTICAL CHEMISTRY
-LONE (LOG E
spectrum of fraction C shown in Figure 5 is almost identical to those of 2-quinolones ( 5 ) ,whereas the spectra of 4-quinolones do not have a band at 277 mp ( I S ) . I n addition, the molar absorptivities of 4-quinolones at 327 mp are about twice those of 2-quinolones. Using the 2-quinolone average molar absorptivity of 6170 liter per mole-cm., a t 327 mp an average niolecular weight of 308 was calculated for fraction C. This is in good agreement with 304 and 285 determined earlier. Therefore, it appears that 4-quinolones, if present, comprise less than 10% of fraction C. 2-Thioquinolones which have a band a t 376 mp (I) xere not detectable. It is probable that such a band would be masked by the spectra of 2-quinolones.
4-QUI NO LONE (LOG E C U R V E )
I
Figure 5. Ultraviolet spectra o f fraction C and two reference compounds
T h e alkyl groups on the hetero rings average Cs in length.
Low Ionizing Voltage M a s s Spectrometric Analysis of Fraction C. Figure 6 shows the lorn ionizing voltage mass spectrometric (LVLIS) d a t a obtained for fraction C. The LVMS data have been deisotoped, and the sensi:bities of all homologous series have been assumed equal. The 2 numbers (CnHz,+,iS) and structural forniulas of the compound types that best fit the chemical and s1)ectral data are shown in Figure 6. For example, the mass peaks for the -9 series started low a t 145 (the molecular weight of' 2-quinolone), reached a maximum a t 215, and formed
Nuclear Magnetic Resonance Spectrometric Analysis of Fraction C.
Semiquantitative nuclear magnetic resonance spectrometric d a t a are in good agreement' with the previously described spectral d a t a . Fraction C contains little, if any, X-alkyl-2quinolones. Aromatic rings are predominantly unsubstitut,ed, and heterocyclic rings are highly substituted.
0
I
I
cz5 250 275 300 325 350 WAVELENGTH I N M I L L I M ICRONS
~
8
IO
12
14
I6
18
20
22
24
26
NQ. CARBON ATOMS PER HETEROCYCLIC MOLECULE Figure 6. Distribution o f thioquinolones, quinolones, and benzquinolones in fraction C as determined b y low ionizing voltage mass spectrometry
a smooth distribution curve. If another - 9 homologous series were present in a significant amount, excluding 4-quinolones, it is quite likely that the distribution curve would show either a shoulder or another peak. Each curve in Figure 6 represents a homologous series present to more than 57c, and all four curves together represent 7575 of fraction C. The remaining 25yc of the total peak intenbities was uniformly divided throughout, the rest of the mass data. Fraction C contained 4i weight. 76 2-quinolones, 11 weight 70benz-.2-quinolones, and 17 weight yo 2-thioquinolones:. The identification of the latter two conipound types must remain tentative until additional inforination is gathered. However, this concentration of 2-thioquinolones is equivalent to 2.1 weight 70 sulfur, which is in good agreement with 1.8 weight % total sulfur found by
elemental analysis. 1-sing a11 of the niass spectral peak intensities, an average molecular weight of 277 was calculated for fraction C. This is in reasonably good agreement with the values of 304, 285, and 308 determined from total nitrogen, infrared, and ultraviolet spectrophotometryJ respectively. ACKNOWLEDGMENT
The experimental assistance and suggestions of G. H. Smith, L. R. Snyder, and €3. E. Buell in carrying out this work are gratefully acknowledged. LITERATURE CITED
(1) Albert, h.,Barlin, G. B., J . Chem. SOC.1959, pp. 2384-96. ( 2 ) ASTAl Standards on Petroleum Products and Lubricants, ASTM D-116057T, pp. 61427, 1958. (3) Bezinger, X . K.,hbdurakhamanov, AI. il., Gal’pern, G. U., Petrol. Cheiri. C.S.S.K. 1, 4Xsi--02(1!462).
(4) Cook, D. J., Yunghans, R . S., Moore, T. It., Hoogenboom, B. E., J . Org. C‘heui. 22, 211-14 (1957). ( 5 ) Grundon, 11. F., McCorkindale, S . J., J . Cheni. SOC.1957, pp. 2177-85. ( 6 ) Jewell, D. AI., Hartung, G. K., J . Cheni. Eng. Data 9, 297-304, (1064). ( 7 ) Knslow, C. E., Cook, D. J., J . A m . Cherri. SOC. 67, 1069-72 (1945). ( 8 ) Katritzky, ii. R., Ambler, A. P., “Physical hIet,hods in Heterocycljc Chemistry, 11,” pp. 262-4, Academic Press, N . Y.) 1963. (9) Price, J. R., Willis, J. B., Ai~stralian J . Cheni. 12, 589-600 (1959). 110) Richter, F. P., Caesar, P. D., Meisel. S. L.. Offenhauer. - , 11. I).., I-n d . ~~
~
Eng. dheni. 44, 2662-5, (1952). (11) Snyder, L. R., Buell, B. E., Proc. Ani. Petrol. Inst. Sect. VIII, 42, 95-9 (1962). ( 1 2 ) Spinner, E., J . Chem. SOC. 1960, pp. i2n-42. (13) Steck, E. -4., Ewing, G. IT.,Xachod, F. C., J . A m . Chem. SOC.71, 238-40
(1949).
RECEIVEDfor review April 3, 1964. Accepted September 1, 1964.
Thickness Measurement of Polymer Films for Infrared Spectrometry by Beta-Ray Absorption Analysis of Ethene-Propene Copolymers TH. A. VEERKAMP, R. J. DE KOCK, A. VEERMANS, and M. H. LARDINOYE Cenfral laboratory, !jtaatsmijnen in limburg, The Nefherlands Determination of the thickness o f films for infrared spectrometric examination may b e accomplished in several ways. In the method described here, use i s m a d e of 6 - r a y absorption. The methnd has several advantages over the conventional procedures for thickness determination. Since there i s no mechanical contact between the measuring device and the sample, the thickness o f rubber films can b e measured without difficulty. The effective! optical thickness i s determined, so that the method i s applicable to films having a rough surface; knowledge of the density o f the film material i s superfluous. The relative error in the determination o f the thickness does not exceed 1%.
Q
polymers by means of infrared spectrometric methods requires knowledge of the sample thickness. In general, infrared spectrometric examination of a polymer is carried out on a film pressed from the polymer or on films cast from solutions. Determination of the film thickness normally presents a niiniher of problems. RIany spectronietrists therefore prefer to rvork with an absorption band which can CANTITATIVE A S A L Y S I S O f
A sample holder can he placed in the ahove mentioned hlock. This sani’ple holder can also be wed in the infrared sl’ectrophotoineter. The dimensions of the sample, a film of the polymcr, are 5 X 17 sq. mm. At about 10 mni. a h o w the source an adjustable Geigerlluller counter, provided with a mica window (2 nig. cin.?) is placed. The auxiliary equipment consists of a power supply! a preset count selector, and an electronic counter. Procedure. The iqotope 6oCodisintegrates via a 8--decay to the -econd excited state of 6on’i at 0.312 m.e.v. This excited state deactivates immediately via two y-quantp, with 1.17 and 1.33 n1.e.v.of energy: respectively, to EXPERIMENTAL the srable 6% isotope. The sensitivity of the employed G.M. Apparatus. h recess constructed tuhe is about 2Tc for the y-quants. in the top of a perspes block contains the sensitivity for the 3 . 5 absorbed by a radioactive bource, consisting of a T o or a 14C derivative. l’he dinienthe titbe being 1 0 0 ~ o . With a very thin layer of a “ T o preparation the sions of the source are about 5 x 18 count rate oliservd by the detecmtor sq. mm. The “Co source consists of a thin will lie> tkterinintd niainly hy the layer of coc‘o3 enriched with fi(CX03, $-particles. TIIP ahaorlition curve varips nrarly t,xponcntially n.ith the abdeposited on a piece of filter paper. The activity of the source is about 0.5 sorhei. thickness i i n d r ~the influtwce, of the energy distribution and scattering. fir. l‘he souwe i.; cowred with a thin I he range of the p-particles is about aluminum film (4 nig. cni.?) stuck on 80 mg. c ~ i i . - ~for “OCo. 1kviations the perspex block with araldite. The 14C source consists of pol~-methyl- from the exponential curve occur above 30 nig. ciii.? methacrylate. thickness 0.3 mni., enI n practice. the film thicmkners needed for infrared 5pectroriched n i t h lacc.The activity is about scoIiic work never (lxcecclq 200 inicronh. 3 uc.
be used as an internal standard. This does away with the need for sample thickness de termination. In many case?, however, internal standards are u$eless owin tallinity or orientation effect The film thickness can be measured in two fundamentally different n-ays-with a simple or modified thicknes gauge or by means of @-rayabsorption. The second method for determining the thickness (2) was suhjccted to a more detailed study. The advantages and the accuracy of this method are emphasized.
r .
VOL. 36, NO. 12, NOVEMBER 1964
2277
