spectra. Components which are poorly resolved on the GLC column can be identified since a mass spectrum can be taken every 1 or 2 seconds and observations of mass spectra can be made almost continuously during the time the efluent passes the ion source. The number of samples that the mass spectrometer can analyze in a day is increased since it is not necessary to break the vacuum to introduce a sample. Solids, liquids, and gases can all be introduced onto the mass spectrometer through the same gas chromatography inlet. The high accuracy and sensitivity and the short time required for the analysis and identification of various compounds that can be obtained by using the mass spectrometer as the detector for a gas chromatograph suggest that this type of compound instrument would be of great use in many quality control and research laboratories. It estends the usefulness of both the gas chromatograph and the mass spectrometer.
j
239
U
Ex
I
211
x
10
x
1
.
1
lZz5
2
.
239 253
I
d
267
’
U
The author thanks Sune I3ergstrom for his interest, encouragement, and support, Einar Stenhagen for many stimulating discussions in the early phases of this work, and Sten Wikstrom and Ilona Lippoy for technical assistance. Thanks are also due to George Waller, Oklahoma State University, Stillwater, Okla., for reviewing this paper. LITERATURE CITED
(1) Bec$y, E. W., “Separation of Iso-
topes, p. 360, George Newnes Ltd., London, 1961. (2) Biemann, K., “Mass Spectrometry, Organic Chemical Applications,” p. 172, McGraw-Hill, New York, 1962.
.
J
’
-
-
Figure 9. High-mass end of mass spectra of components C24 and Czs from chromatogram of paraffin (Figure 8) The compounds were identitled os n-tetrocorone (mol. wt. 238)and n-pentacosane (mol. wt.) 352
(3) Brunnke, C., Jenckel, L., Kronen-
ACKNOWLEDGMENT
~ m/o
berger, K., ASTM Committee E-14 Meeting, Yew Orleans, La., 1962. (4) Dorsey, J. A., Hunt, R. H., O’Neal, M.J., ANAL.CHEM.3 5 , 511 (1063). (5) Ebert, A. A,, Zbid., 33, 1865 (1961). (6) Gerson, T., Hawke, I. C., Shortland, F. B., Biochem. J . 74, 366 (1960). ( 7 ) Gohlke, R. S., ANAL. CHEM. 31, 535 (1959). (8) Haathi, E., Scand. J . Clin. Lab. Invest. 13, suppl. 59 (1961). (9) Hansen, R. P., Shorland, F. B., Cooke, J. S . , Riochem. J . 77,64 (1960). (10) Hornina. E. C.. Moscatelli, E. A., Sweeley, C., Chem. I n d . 1959, 751: (11) Lindeman, L. P., Annis, J. L., ANAL.CHEM.3 2 , 1742 (1960). (12) Ryhage, R., Arkiu. Kemi 2 0 , 185 (1962). (13) Ryhage, R., Stallberg-Stenhagen, S., Stenhagen, E., Ibid., 14, 247 (1959). (14) Ryhage, R., Stallberg-Stenhagen, S.,
c:
~
Stenhagen, E., Karolinska Institutet, Stockholm, Sweden, unpublished data, 1961. (15) Ryhage, It., Stenhagen, E., Arkiv Kemi 13, 523 (1959). (16) Zbid., 15, 291 (1960). (17) Ryhage, R., Sydow, E. von, Acta Chem. Scand. 17, 2025 (1963.) (18) VBradi. P.. Ettre., K.., ANAL.C H E M . 3 4 . 1417 (1962). (19) ’VAradi, P.,’ Ettre, K., Zbid., 3 5 , 410 (1963). RECEIVED for review October 16, 1963. Accepted December 5, 1963. This work was made possible by grants from Knut and Alice Wallenbergs Stiftelse, Svenska Tobaksmonopolet AB, Magn. Bergvalls Stiftelse, Therese och Johan Anderssons Minne, and from Statens Medicinska, Naturvetenskapliga and Tekniska Forskningdd.
Reaction of Ethers with Acetyl Chloride and the Identification of Products by Gas Chromatography PAUL WASZECIAK and HERBERT G. NADEAU 0th Research Center, 0th Mathieson Chemical Corp., New Haven, Conn. 06504 The reaction of simple and polymeric ethers with acetyl chloride in the presence of a strong Lewis acid salt has been studied. Reaction products have been isolated and identified as the corresponding chloroacetates. Optimum conditions for quantitative conversion have been found and utilized to develop a procedure for the classification of ethers. The procedure has been applied to polyglycol ethers containing, in some instances, mixed ether groups. Gas liquid chromatography is used for the
764
ANALYTICAL CHEMISTRY
determination of reaction products. Colored compounds are formed during the reaction which appear to b e linearly related to the concentration of the polyether. Possibilities of a new colorimetric method are presented.
P
polymers of various compositions are commercially available and find many applications. These materials usually are made by ethoxylation andjor propoxylation of low molecular weight OLYOXYALKYLENE
alcohols. The degree of hydroxyl functionality of the alcohol controls the number of terminal hydroxyl groups in the resulting polyether. Consequently, mono-, di-, and trihydroxy polyethers are available. For some applications, the hydroxyl groups are reacted to form the polyether alkoxy compound, where usually the terminal alkyl group is C1-C9. Generically, the compounds can be represented by the following formula;
would offer a convenient method of classification. The identification of the products could be achieved by saponification of the ester or by gas liquid chromatography (GLC). The reaction, applied to polyethers, would be as follows:
where
x = 0-whole number, Y = 0-whole number, z
= 1-whole
RI =
RP
=
number, depending on functiona,lity of alcohol, H or alcohol carbon base with functionality or 1-3, H or C1-C4 alkyl group.
Characterization of an unknown polyether with existing snalytical methodology is difficult. Csually, a combination of analytical methods is required. Hydroxyl groups are determined according to the procedure of Elving and Warshowsky as described b y Siggia (C), and give a number average molecular weight if a definite functionality of the polymer can be assumed. The procedure of Seumann and Nadeau (2) is useful for the detection of terminal alkoxy groups containing a carbon chain greater than the back 3one of the polymer and for the determin:ttion of the general class of the polymer The presence of methine linkages is (determined by the procedure of Ring (3). This procedure is adequate for the determination of propoxy groups in po ymers of this type. 8iggia (6) reacted ethoxylated compounds with hydriodic acid to effect ether cleavage with subsequent formation of ethylene. I'ropoxylated compounds react similarly, but also result in complicated side reactions. Yuclear magnetic resonance ( N l I R ) is capable of determining the basic
Table 1. Inorganic Salts Used to Effect Reaction of Polyethers with Acetyl Chloride
Salt AlC13 ZnCh FeCla HgClz BaCh LiCl PbOOCCHJ cuso, BFa.EbO CaC12
Table II.
Reactivity Fast Fast Fast Slow None None None Very slow Fast None
Color Wine red Wine red Wine red Wine red Colorless Colorless Colorless Yellow Wine red Colorless
Elemental analysis c, %J H, %
Figure 1. GLC chromatogram of reactor products of Poly G 3030 PG showing incomplete reaction Air or HCl Acetyl chloride 3. Acetic acid 4. Dichloropropane and/or propyl acetate 5 . Acetic anhydride 6. Unknown 7. Chloropropyl acetate 8. Propylene glycol diacetate 9. 1,3-DichIoropropyl acetate 10. 3-Chloro- 1,2-propanediol diacetate 1 1 . Glycerin diacetate 12. Dipropylene glycol diacetate 13. Glycerin triacetate 14. Tripropylene glycol diacetate
structure of many of the polyether types, but not always can detect the existence of terminal alkyl groups by reason of their low concentration ( I ) . I n an attempt to develop a method of classification which is less dependent on instrumental techniques and which might be more sensitive, the reaction presented by Underwood ( 6 ) , 0
'I
+
ZnClz
//O RC-OC*Hs ( R = acetyl)
+ CZHrCl,
has been investigated. It seemed apparent that, if the above reaction were applicable to all ethers, then identification of the products
Sapohification no. IR
Chloropropyl acetate
43.9 6.7 26.0
416 12ster
411
CHaC-C1 CH3 0
I
Fraction #2
Glycol diacetate
52.3 7.7 1.2
52.5 7.54 0
711; 714
768
Ester
ZnCI?
1
either
I
II
CI(CHzCH0) *CCHa
or 0
CICHzCHzOC'
1. 2.
C ~ H ~ O C I H RC-CI ~
'43.7 6.8 :!6.3
1
TH8
P
Identification of Components Isolated from Reaction of Polyethers with Acetyl Chloride -k ZnCh
Fraction #l
c1. 70
r
Ri O(CH?CH?O)z(CH?CHO),Rz -t
CH3
REAGENTS APPARATUS AND ANALYTICAL CONDITIONS
Ferric chloride
Baker and Adamson Sublimed J. T. Raker ChemAcetvl chloride ical Co. Silicone oil DC 550 Dow Corning Chromosorb W JohnP-Manville F & M Model 300 Instrument Column (aluminum) I-meter DC 550 silicone oil on Chromosorb W Detector Thermal conductivity cell, 100,000 ohm Detector current 150 ma. Column tempera75' 9'/minute, ture programmed to
+
Injection port temp. Flow Block temperature Sample size Chart speed
200" 2.50" C.
c.
90 ml./minute 250" C. 5 pl:
4 minutes/inch
EXPERIMENTAL AND DISCUSSION
Initially, polypropylene glycol (PPG) of molecular weight 3000 was reacted with acetyl chloride and zinc chloride in a 1:Z:O.z weight ratio. An ester product was isolated by distillation, which was characterized by boiling point, saponification number, infrared (IR) spectrum, and elemental analysis as chloropropyl acetate. Tn addition, a second product was separated and identified as the diacetate of propylene glycol. One difficulty in this reaction is the relative insolubility of zinc chloride in the reaction mixture, which presents two-phase medium for reaction. The reaction was screened with several other salts (see Table I ) ; and ferric chloride, because of its solubility in the reaction mixture, was chosen for further work. A reaction was completed with ferric chloride similar to that previously completed with zinc chloride. The same products were isolated. Table I1 shows the properties of the products. A study of the extent of reaction was initiated. To 1.5 grams of polyether (Poly G 3030 PG), 7 ml. of a solution containing 64 grams of FeC& per liter VOL. 36, NO. 4, APRIL 1964
765
1
Table 111. Propoxy/Ethoxy Ratio of “Block Polymers” Compared with NMR Results and Manufacturer’s Claims 2
Wyandotte Plu-
4
ronic“ L-42 L-43 L-44 L-61
D
P!4
Manufacturer’s valueb
Acetyl chloride cleavage
NMR resultsc
3.0 1.8 1.1 6.9
2.2 1.8 1.0 3.6
2.1,2.0 1.3, 1.3 1.0, 1.0 4.6,4.2
I ’
a Samples obtained from the Wyandotte Chemical Corp., Wyandotte, Mich. * Data obtained from Wyandotte Pluronic Grid, published by Wyandotte Chemical Corp. c Unpublished method of Olin Mathieson Chemical Corp.
3
PVLYPROPYLENB GLYCOL 3030 ffi
RETENTION TIME
- Minutes
Figure 2.
GLC chromatogram of Poly G 3030 PG reacted with FeC13-acetyl chloride under conditions I. 2. 3. 4. 5.
finalized
analytical
Acetyl chloride Acetic acid Acetic anhydride Chloropropyl Propylene glycol diacetate
of acetyl chloride were added, and the mixture was held a t reflux temperature for hour. The products were examined by GLC. Figure 1 shows an actual chromatogram of the reactor product?. Identification of most of the observed peaks was made on the basis of retention time of standards. Retention times of expected compounds are also shown by an arrow. It is seen from the figure that products are present representing more than one monomer unit, indicating incomplete reaction. Also, since products such as propylene glycol diacetate were found, rupture of the ether bond appears to be occurring in a random fashion. Random cleavage of the polyether could result in the formation of chloroalkyl acetate, alkyl diacetate, and alkyl dichloride. In the event of incomplete reaction, the corresponding polyethers would be present. The initiator or alcohol used for the polyether preparation would give rise to a number of products, depending upon the functionality of the alcohol. I n general, alkyl chlorides, alkyl acetates, or compounds of mixed acetate-chloride functionality would result. Attempts were made to increase the extent of reaction, using sealed tubes at 100” C. for extended periods of time up to 24 hours. The changes produced were not significant. Subsequently, i t was found that, by increasing the concentration of ferric chloride, the reaction went 766
0
ANALYTICAL CHEMISTRY
to completion-that is, the concentrations of the compounds containing more than one monomer unit were reduced, while there was a corresponding increase in concentrations of the chloropropyl acetate, dichloride, and diacetate. Thus, if a 1 : l : l ratio of components is mixed at 0’ C. in a flask and brought to room temperature, the resulting chromatogram indicates complete reaction. Figure 2 is a chromatogram of Poly G 3030 PG reacted under the finalized conditions. With these improved conditions, several types of polyethers were reacted. These polyethers were made from ethylene oxide (Carbowax), 1,2propylene oxide (PPG 1800, 3000 triol, 300 diol), and 1,4-butylene oxide (tetrahydrofuran). Chromatograms showing the reaction products of Carbowax 2000, Poly G 3030 PG, and 1,4-butylene oxide are shown in Figure 3. The chromatograms show that complete reaction was obtained with each type of polyether; however, it is seen that the way in which acetyl chloride reacted is different. I n the case of the ethoxylated polymer, only chloroethyl acetate was observed, while with Poly G 3030, both chloroisopropyl acetate and the isopropyl diacetate were observed. Although it was expected that the butylene oxide polymer would react similarly to the ethylene oxide compound, it is shown that both chlorobutyl acetate and butylene diacetate are present. The peak emerging after the diacetate was not identified. I n addition to the above compounds, block polymers (Wyandotte’s Pluronics) mere reacted. These compounds consist of a polypropylene oxide nucleus onto which ethylene oxide has been polymerized. From the chromatograms of the reaction products, it was possible to calculate the ratios of propoxylene oxide to ethylene oxide monomer used to form the polymer. These data were compared with ratios calculated from an
I
2
RETENTION TIME
-
Minutes
Figure 3. GLC chromatograms of polyethylene, polypropylene, and polybutylene glycol reaction products after reaction with FeCI3 and acetyl chloride I. 2. 3.
Chloro olkylacetate Alkyl glycol acetate Unknown
XMR study of these block polymers. The S M R values were based on the fact that the total number of equivalent protons is proportional to the areas under the curves of the specific absorption lines. This information was compared to data from the manufacturer of the composition of these materials. The results of NMR analysis and the results of GLC analysis of the reaction products shown in Table 111 indicate reasonably good agreement and compare favorably with the compositions indicated by the producer of the polymer. These data also indicated that the reaction had cleaved the polymer completely. During this study, it mas noted that a distinct color change occurred on the addition of polyether to the reaction mixture. Therefore, a short study was undertaken to develop a colorimetric technique for determining the polyether concentration. Dilute solutions of ferric chloride in avetyl chloride mere combined with various concentrations of polyether, and their absorption
spectra were determined in the range of 400-500 mp. An absorption band was found with maximum at 455 mp. It was further found that Beer's law was obeyed with respect to polyether present. A 0.1 weight solution with respect to the polyether (2000 mol. wt.) gave an absorbanccb of 0.04. This particular aspect of the reaction is of interest at the preecnt time. When acetyl chloride and FeC13 are reacted with simple aliphatic ethers, the resulting chloroalltanes and acetates can be readily detecled by GLC. All ethers studied have been found to react.
The determination of the acetate by saponification in situ is not feasible because of interferences from the ferric chloride. The method using GLC, however, is a simple method for the identification of ether mixtures. Work has been presented which shows that the reaction of polymeric ether with acetyl chloride and ferric chloride in conjunction with GLC examination of products yields structural information. The information obtained by the procedure has merit in that it is in agreement with the data from other methods.
LITERATURE CITED
( 1 ) Agahigian, H., Olin Mathieson Chem-
ical Coy., New Haven, Conn., unoublivhe work. 1962. ( 2 ) Neumann, E: W., Nadeau, H. G., ANAL.CHEM.35, 1955 (1963). (3) Rim, R. D., 7th Detroit Anachem ConfGence, Detroit, Mich., October,
1959. (4) Siggia, S., "Quantitative Organic Analysis via Functional Groups," 3rd ed., p. 20, U'iley, New York, 1963. ( 5 ) Zbid., p. 213. (6) Underwood, H., J. Am. Chem. SOC. 52, 387 (1930).
RECEIVED for review October 14, 1963. Accepted January 8, 1964.
Characterization and Routine Determination of Nonbasic Nitrogen Types in Cracked Gas Oils by Linear Elution Adsorption Chromatography L. R. SNYDER and B. E, BUELL Union Oil Company o f Californiu, Union Research Cenfer, Brea, Calif.
b
Nitrogen present as alkyl indoles, carbazoles, and berizcarbazoles (indole derivatives) can be rapidly and quantitatively determined in cracked gas oils boiling below 950" F. The indole derivatives are first separated by a combination of ion exchange and linear elution adsorption chromatography, and the inclividual nitrogen types are determined by their absorbance in the ultraviolt!t. These indole derivatives account For an average of over 80% of the ironbasic nitrogen in cracked samples boiling above 500" F. N-alkyl-substituted indole derivatives are not determined, but these compounds do not appear to be important constituents in cracked streams. The relative occurrence of the various benzcarbazole isomers can also be determined. For the cracked gas oil samples so far examined, the approximate relative concentrations of these isomers a re: 1,2 benz1:arba zole, 85%; 2,3-benzcarbazole, and 3,4benzcarbazole, 15%.
-
I
Oyo;
RECEXT YEARS, interest has increased in the relative occurrence of various nitrogen conipounds in petroleum gas oils (400' to 1000" F.). The importance of nitrogen compounds in determining pr0duc.t quality (color stability, gum formation, etc.) and feed response toward catalytic processinq is now generally recognized. Previous studies of the nitrogen types that occur in petroleum have tendrd to emphasize the basic nitrogen tyoes, although in catalytically cracked :as oil fractions N
that boil above 500' F., nonbasic nitrogen constitutes 80 to 90% of total nitrogen. The determination of nonbasic nitrogen types in cracked gas oil fractions is therefore of considerable interest. The derivatives of pyrrole (indoles, carbazoles, etc.) are known to be important contributors to the total nonbasic nitrogen of cracked gas oils. Numerous workers have observed the presence of indoles and carbazoles in cracked gas oil fractions (7. 8, IO, 151 7 ) ; one study (15) shows pyrrolic nitrogen compounds to comprise 74% of the nonbasic nitrogen in a 480" to 540' F. sample. A number of colorimetric (8. 12) and nonaqueous titration (1, 14) procedures have been described for the determination of some or all of the pyrrole derivatives in petroleum samples. These methods generally suffer from incomplete determination of given pyrrole types, interference from other sample components, and/or lack of specificity among the various pyrrole derivatives, and they may have only qualitative significance. X o adequate check has yet been reported on the accuracy of any of these techniques for direct application to typical petroleum samples. The technique of linear elution adsorption chromatography (LEAC) has been shown useful in the determination of a number of the minor constituents of petroleum (19-21), and its application to the analysis for the various pyrrole derivatives in petroleum looked promising initially. The present communica-
tion describes the results of this study as applied to the analysis of cracked gas oil fractions; a subsequent publication will explore the application of LEAC nitrogen-type analysis to straight-run petro!eum samples. EXPERIMENTAL
Routine LEAC Determination of Nonbasic Nitrogen Types in Cracked G a s Oils. REAGENTS. Chromatographically standardized 2.07& H20A1203 (Xlcoa F-20, equivalent linear retcntion volume equals 4.0 ml. per gram for elution of naphthalene by n-pentane) is prepared as previously (22). Phillips 99% n-pentane is purified by passage over activated silica gel (20 ml. per gram). Reagent grade methylene chloride and benzene are used. Duolite C-10 cation exchange resin (100 to 200 mesh) in the methanol wet acid form is prepared as previously (27), rinsed with 2 to 3 washes of benzene, then with 3 to 5 washes of pentane. The resin is stored under pentane, and air-dried to give a free-flowing powder immediately before use, as described below. PROCEDURE. Sample basic nitrogen is first removed as follows. Approximately 0.5 gram of sample is weighed into a 5-ml. volumetric flask and brought t o mark with benzene. For samples boiling below 725' F., approximately 0.1 gram of air-dried cation exchange resin is then weighed into the flask. For samples boiling above 725" F., approximately 0.2 gram of the resin is added. The flask is shaken by hand at 5- to IO-minute intervals for 15 to 60 minutes from the time the resin was added, and the supernatant solution is used as VOL. 36, NO. 4, APRIL 1 9 6 4
767
