and erroneous results. The wide range in melting points for the addition compounds of these two substances reported in Table I1 is believed to result from a combination of these effects. With the above two exceptions of the compounds reported in Table 11, the behavior of benzene derivatives IT ith 2,4,7-trinitrofluorenone is analogous to that of naphthalene derivatives and the same reagent. A number of other benzene derivatives were tested with 2,4,T-trinitrofluorenone. Aniline derivatives, such as A'-methylaniline, A',AV-dimethylaniline, N,S-diethylaniline, m-phenylenediamine, and p-phenylenediamine form molecular addition compounds with 2,4,7 - trinitrofluorenone in a mixed fusion. However, because of the intense colors formed in the mixing zone, it was extremely difficult to determine the eutectic temperatures and particularly the melting points of the addition compounds. Molecular addition compounds form between 2,4,7-trinitrofluorenone and mesitylene, anisole, and m-dichlorobenzene in a mixed fusion. On heating, these compounds ITere so volatile that they distilled or sublimed an-ay from the preparation before the significant temperatures could be measured. This represents an important limitation on the use of 2,4,7-trinitrofluorenone with some benzene derivatives.
With the temperatures reported in Table 11, there is an uncertainty of *0.5" C. unless a temperature range is quoted. DISCUSSION
The original mixed fusion data (4) have been extended t o include 14 additional naphthalene derivatives and 11 additional benzene derivatives. Examination of the original data and the data in Tables I and I1 shows that most of the compounds of approximately the same initial melting points may be differentiated on the basis of the color of the 2,4,7-trinitrofluorenone molecular addition compounds and the significant temperatures as measured in the mixed fusion technique. Of the benzene derivatives tested, some behave in a mixed fusion similar to polynuclear aromatics. This is particularly true of those melting above 60" C. and those which exhibit a low vapor pressure a t the temperatures employed. However, even with the small number of benzene derivatives tested, 2,4,7-trinitrofluorenone is of more limited applicability to the benzene series than to the polynuclear series. The higher volatility of benzene derivatives makes the identification of certain members of this class difficult or impossible if 2,4,7-trinitrofluorenone is the reagent. It is to be expected that many benzene derivatives which form
2,4,7-trinitrofluorenone molecular addition compounds will be too volatile for the significant temperatures to be measured. It may be possible to modify the method by the liquid chamber technique (1) or the salt chamber technique (5) to overcome these difficulties. These modifications have not been tried in the present work. The intense colors observed n-ith the aniline derivatives are a further limitation of the method. With an ordinary light source, it vr-as extremely difficult to determine the significant melting points. It is possible that a stronger light source or the proper filter system would overcome this difficulty. This was not tried in the present work. LITERATURE CITED
c. J., ANAL. CHEM.2 5 , 486 (1953). Laboratories, Leominster, Mass., Data Sheet, "2.4.7-Trinitrofluorenone," 1954. (3) Kofler, A., Chem. Ber. 84, 427 (1951). (4) Laskowski, D. E., Grabar, D. G., RlcCrone, W. C., ~ A L CHEY. . 25, 1400 (1953). (5) Laskowski, D. E., RlcCrone, JV. C., Ibid., 26, 1947 (1954).
(1) Arceneaux, (2) Dajac
RECEIVEDfor review April 15, 1957. Accepted Kovember 26, 1957. Based upon thesis submitted in June 1956 by Donald E. Laskowski to the Graduate School of Illinois Institute of Technology in partial fulfillment of the requirements for the degree of doctor of philosophy.
Infrared Spectra of Oxirane Compounds Correlations with Structure JOSEPH BOMSTEIN Becco Chemical Division, Food Machinery & Chemical Corp., Station 6, Buffalo 7, N. Y.
b Infrared absorption spectra of 1 1 oxirane ring compounds have been recorded in the 2- to 15-micron region. These are chiefly nonterminal epoxides. Based on these and previously published data, tentative correlations have been established for oxirane type, using the 12-micron band as a key to structure. Trisubstituted rings have a band a t 13.0 to 13.3; disubstituted rings have a band a t 11.8 to 12.9; and monosubstituted rings have a band a t 11.4 to 12.4 microns. Oxirane rings were found to form molecular iodine complexes.
E
on the identification of bands associated with the oxirane ring was adequately described b y Patterson (8). Later publications (4, 7 , 10-12) were concerned with compound synthesis, and spectra shown were not interpreted. ARLY WORK
544
ANALYTICAL CHEMISTRY
Most recently, Henbest and coworkers (6) developed a general correlation for the C-H stretching band as found in oxirane rings. It was shown that a band near 3000 em.-' shifted toward a lower frequency with increasing substitution of the ring, and that attachment of an epoxy methine group to a strained ring resulted in a n increase of absorption frequency. These observations, plus comparison between epoxide and saturated parent compound, provided evidence for the origin of the band. Detection by this correlation would be subject to masking effects in the presence of many types of structure, and therefore has limited use. As far as can he determined from published data, the present status of infrared study of oxirane compounds is that ring vibrations have been tentatively assigned to three wave length ranges: 7.8 to 8.1. 10.5 to 11.6, and
11.5 to 12.7 microns. As noted in the combined work of Patterson (a), Shreve and coworkers (9), and Field and coworkers (S), the 8-micron band is fairly constant for all types of molecules; the 11-micron band position is variable, and has been related to structure in a general sense; and the 12-micron band position is sensitive to structural changes. Patterson examined chiefly molecules having a terminal oxirane ring. Shreve obtained data for longchain, internal-oxirane compounds. The present work discusses the spectra of a group of epoxides of widely varying structure and correlates these with previously published spectra. EXPERIMENTAL
Spectra were made with a Baird AB-2 spectrometer, using rock salt prism and cells. Samples were run either as undiluted liquids in thin cells or as solu-
Table 1.
Spectra of Compounds Examined“ (Wave length of absorption peaks in micronsb) A B C D E F G H I J K m 7.90 m 7.66 m 7.69 m 7.47 m 7.75 m 7.80 m 7.92 m 7.59 s 7.98 m 7.98 m 7.71 8 8.08 m 8.02 m 7.83 m 7.57 s 7.98 m 7.92 m 8.02 m 7.72 w 8.19 m 10.72 m 7.81 m 8.21 s 8.29 m 7.95 m 7.63 m 8.32 m 8.39 TV 8.20 m 7.93 n- 8.36 m 10.93 s 8.09 m 8.32 s 8.47 m 8.02 s 7.92 m 8.60 m 8.54 m 8.48 m 8.00 m 8.85 m 11.78 m 8.21 s 8.95 s 8.94 m 8.28 m 8.16 w 8.85 R’ 8.70 m 8.52 m 8.05 w 9.30 s 11.98 m 8.52 B 9.43 m 9.14 m 8.47 m 8.36 m 9.02 m 9.20 m 9.60 m 8.10 m 9.50 m 13.83 m 8.69 m 9.67 s 9.63 m 8.90 w 8.65 s 9.35 m 9.44 s 10.05 m 8.22 m 10.05 m 8.86 s 10.57 m 9.85 m 9.04 m 8.92 m 9.60 ni 9.62 m 10.26 w 8.70 m 10.73 m 9.28 m 10.87 m 10.32 m 9.38 E! 9.15 w 9.72 m 10.05 m 10.32 w 9.12 s 10.88 s 9.59 s 11.11 s 10.55 s 9.63 m 9.25 m 10.00 s 10.35 s 10.98 m 9.55 w 11.27 w 10.01 s 12.33 s 11.32 m 9.79 w 9.39 s 10.45 s 11.22 m 11.48 m 9.65 m 11.80 w 10.33 s 13.30 s 11.88 m 9.92 m 9.47 m 11.00 s 11.40 m 11.73 m 9.79 s 11.98 m 10.90 s 14.39 s 13.13 w 10.29 m 9.59 s 11.35 s 11.93 s 12.31 in 10.03 JY 12.70 w 11.00 s 14.92 TY 10.50 m 9.90 m 11.45 m 12.31 s 12.59 m 10.30 \v 13.16 m 11.39 m 10.63 m 10.05 s 12.62 s 12.80 m 13.33 m 10.78 w 13.52 m 11.63 s 11.10 s 10.37 s 13 35 s 13.40 m 11.12 IV 13.78 m 11.77 s 11,75 m 10.62 m 13.70 s 11.78 m 11.83 s 11.98 m 10.72 m 14.07 s 12.05 m 11.95 s 12.51 m 11.15 m 12.59 m 12.29 s 13.09 s 11.70 m 12.98 u‘ 12.70 s 11.91 m 13.07 w 12.95 v- 13 59 m 12.23 m 14.53 s 13.30 s 13.03 s 14.57 m 14.40 a A. 2,3-Epoxy-2,2,4-trimethylpentane.B. 1,2-Epoxy-p-menthane. C. (1,2))(S,g)-diepoxy-p-menthane. D. 2,3-Epoxypinane. E. 1,2-Epoxg-2,2,4-trimethylpentane. F. Epoxycyclohexane. G. 4-Vinyl-1,2-epoxycyclohexane. H. (4,5), (8,9)-diepoxytricyclo(5,2,1,0z~~)decane.I. 1,2-Epoxyoctane. J. 1,2-Epoxydodecane. K. Phenyl glycidyl ether. s = strong; m = moderate; w = weak.
tions in carbon disulfide. Iodine complexes were prepared by miying equal volumes of carbon dirulfidc qolutions, each c o ~ t a i n i n gtwicr the desired final concentration of the component involved.
Compounds A
MATERIALS
C
All compounds nere prepared and purified in this laboratory. Purity was greater than 95% for most samples, and slightly less for others, as determined by any of three methods: titration with hydrobromic acid ( I ) , zinc bromide isomerization ( 2 ) . or infrared quantitative analysis. Most samples contained traces of impurities, such as residual olefin, or ring-opened and/or isomerized product. Data quoted from other sources were not generally checked by examination of the same compounds in this laboratory, as spot checks oyer several years’ time have shown them to be reliable. METHODS
OF IDENTlFiCATlON
Two techniques were used in identifying oxirane group bands. The first was that described by Patterson, involving comparison of spectra of the saturated parent, the olefin, and the epoxide. The second method was based on recent work on charge-transfpr complexes, especially that of Gluslter and Thompson ( 5 ) . These authors reported the formation and nature of complexes of iodine and iodine cyanide with some oxygen- and nitrogen-containing compounds. I n the present nork it was found that complexes are also formed between iodine and epouides in carbon disulfide solution, and that these complexes cause shifts and intensity changes in the infrared region. Bands not associated with the epoxy ring appear unaffected b y the presence of iodine.
Table 11.
B
a
S o . of Ring
Substituents 3 3 3
D E C F G H I 1 J 1 I( 1 See Table I for key.
Probable Epoxide Bands
Xear
8 Microns
7.90 8.02 8.02 7.92 7.98 7.95 7.92 7.92 7.93 7.98 7.98 8.09
Insufficient samples have been examined to detect a pattern in the direction and magnitude of shifts and intensity changes. Certain of the samples undergo a chemical reaction Trith iodine, and so cannot be treated in this fashion. The study of the complexes themselves and their effects on infrared and ultrayiolet spectra is not reported here. RESULTS AND DISCUSSION
Table I lists bands and their relatire intensities in the 8- to 15-micron region. Table I1 lists compounds examined and bands probably associated with the oxirane ring. I n Table 11, number of ring substituents means the number of R,’s which are not hydrogen in the generalized molecule,
SFar 11 LIicrons 12.33
Xear 12 Microns
11.88
11.98 11.91 11.35 11 . i 5
11.22 10,98 10:88 10,93 10.90
12.31 11.78,12.05 11.98 11.98 11.95
No-other restriction is implied. The column headed ‘hear 12 microns” lists bands in decreasing order of absorption 1%-avelength. Several compounds have been reported previously, but are repeated here because of poor resolution of the older spectra. Most samples shorn bands in the 14to 15-micron region which may also be associated with the oxirane ring. These were also shown, but were not reported, in previously published spectra. They are of moderate to strong intensity, are absent in parent compound spectra, and shift on iodine complex formation. No obvious correlation could be made for them. If all the data published to date, and t o which reference has been made in this paper, are considered, approximately 50 to 60 compounds have been examined. These include a limited number of highly substituted rings and a larger number of monosubstituted VOL. 30, NO. 4, APRIL 1958
545
rings. This is at least sufficient to establish a tentative correlation, which is apparent from the 12-micron band positions. Compounds having three ring substituents absorb strongly a t 13.0 to 13.3 microns. Those with two ring substituents absorb a t 11.8 to 12.9 microns, and those which are monosubstituted absorb a t 11.4 to 12.4 microns. Substances in which a ring bond is conjugated with an unsaturated group-e.g., olefin or phenyl-show a pronounced shift to a longer wave length, as suggested by Patterson. A11 oxides newly reported have a band a t 7.8 to 8.1 microns. However, the 11-micron band range should be extended from 10.5 to 11.6 to 10.5 to 12.3 microns to include the nonterminal oxirane ring. Other compounds examined in this laboratory tend to substantiate these
correlations. They are omitted here because they are not single isomeric forms. A number of 11- and 12-micron bands are very intense and are suitable for routine infrared quantitative procedures. Some have been used for this purpose in this laboratory for several years. ACKNOWLEDGMENT
The author wishes to express his appreciation to Becco Chemical Division for permission to publish this m-ork, and to the members of the research department who prepared and purified some of the samples. LITERATURE CITED
(1) Durbetalri, A . J.,
2000 (1956). (2) Zbid., in press.
A s . 4 ~ .CHEL
28,
Field, J. E., Cole, J. O., Woodford, D. E., J . Chem. Phys. 18, 1298 (1950). Gasson, E: J., Uillidge, A . F., Primavesi, G. R., Webster, TI7., Tounr. D. P.. J . Chem. SOC.1954. 2161. Glusker, D. L., Thompson, H. I\-., Ibid., 1955,471. Henbest, H. B., Meakins, G. D., Nicholls, B., Taylor, K. J., Ihid., 1957, 1459. Ilwart, H., Vosburgh, W,G., J . -1m. Chem. SOC.76, 5400 (1954). Patterson, W. A , , ANAL. C H m i . 26, 823 (1954). Shreve, 0. D., Heether, 11. R., Knight, H. B., Sn-ern, D., Zbirl., 23, 277 (1951). Stevens, C. L., Farkas, E., Gillis, B., J . Am. Chem. SOC.76,2695 (19.34). Walborsky, H. AI., Loncrini, 11. F., Zbid., 76, 5396 (1954). Wasserman, H. H., Aubrey, S . E., Ibid., 77, 590 (1955). RECEIVEDfor review June 7 , 1957. -1ccepted January 6, 1958. _ I
Chromatographic Determinutio n of Stea m-VoIa ti Ie Acids in Cigarette Smoke SIR: The unidentified acid fraction folloning formic acid on partition Chromatography of the steam-volatile acids of cigarette smoke ( 2 ) is derived from materials used in the chromatographic analysis and not from the smoke sample. Glycine (aminoacetic acid), used in buffering the column a t p H 2.0 constitutes about 70% of this fraction and a t least one other acid is present. Uniform background acidity throughout the separation a t pH 2.0 and, to a lesser extent, the separation a t p H 8.7 is significant when small amounts of acids are being analyzed. This acidity is most noticeable when the solvent composition reaches 257, 1-butanol in chloroform. Although the original report by Corcoran (3) on this method did not mention the presence of blank
Table I.
Blanks f o r Elution of pH 2.0 and 8.7 Columns with 1-Butanol-Chloroform Mixtures
Column pH 2.0
2.0
2.0 8.7 8.7 8.7 a
acidity, the present investigation indicates the desirability of performing blank runs a t column p H values below 8 to 9. The blanks are affected by variables, such as technique of column preparation and reagent quality. Table I does not necessarily represent standards for this analysis. Identification of eluted acids was confirmed ( 2 ) by paper chromatography of their ammonium salts. Hon-ever. volatilization of these salts during a concentration step in their preparation has led to the failure of detecting small amounts of the higher acids. This difficulty has been eliminated by the successful use of sodium salts in the same chromatographic system. illthough this modification makes possible the direct use of the titrated eluent,
70 1-Butanol
in Chloroform 1
10 25
1 10
25
Blank per 5-111. Eluent" 1Il. 0.0197N NaOH Meq. 0.01 0.0002 0.03 0 . 14b 0.01
0.01 0.03
Containing 2 drops 0.170 bromothymol blue in methanol. (0.074 meq.) had passed.
* After acidity peak 546
ANALYTICAL CHEMISTRY
0,0006
0.0028* 0.0002 0.0002 0.0006
which simplifies considerably the identification procedure, indicator interference prevents this approach with the most mobile acids. EXPERIMENTAL WORK A N D RESULTS
Unidentified Acid Fraction. Sevei a1 repetitions of the procedure (2) for isolation and chromatographic separation of volatile acids from cigarette smoke indicated that the aniount of the unidentified acid fraction (I) was largely independent of the size of smoke sample. This suggested acid (I)was associated nith the analysis materials rather than with the sample [substantiated by the discovery of a similar acidity peak (11) on chromatography of a known mixture of acids and also in a mere elution of a blank column]. Acids I and I1 (applied as ammonium salts) each had a single spot a t R, 5 when paper chromatographed in the 1-butanol-water-propylamine system ( 2 ) . Glycine also had this R,; its presence as a major constituent of acids I and I1 was further suggested by these fractions giving positive ninhydrin tests. Paper chromatography of the ammonium salts in ethyl Cellosolve-n-aterconcentrated ammonium hydroxide (80 to 15 to 5 v./r.) ( I ) , revealed that a n acid other than glycine was also present and indicated further identity of acids I and 11. Spots on these chromatograms were made visible under ultraviolet light n-ith 8-quinolino1, used by
