M. J. MURRAY AND FORREST F. CLEVELAND I
I
I
I
Vol. 63
that the oxidation, if occurring, depends to a large extent upon the nature of the solvent used. It would be interesting to study how pyridine differs from alcohol in influencing this decomposition of rotenone, but the fact that pyridine and rotenone both show high absorption in about the same region of the spectrum makes such a study impossible. On the other hand, the effect of light on the decomposition of rotenone is very marked. It should be noted that the absorption spectra for both of the exposed solutions, that is, the solutions saturated with carbon dioxide and with oxygen (Fig. 1))gradually changed in shape as the period of exposure increased, until the absorption maxiinum finally disappeared altogether. It is apparent from the curves that for the same period of exposure the absorption spectra of carbon dioxide and oxygen treated solutions differ only slightly. This slight difference could mean only that the effect of oxygen in the photo-decornposition of rotenone is a t least very small.
2500 2900 3300 3700 Wave length in A. Fig. 2.-Absorption curve of rotenone in ethyl alcohol solution. The plotted curve is for the solution measured immediately after preparation and not saturated with Summary either oxygen or carbon dioxide; the observed values for Study of the absorption spectra of solutions of similar solutions kept in the darkroom for twenty days rotenone in ethyl alcohol, saturated with carbon and saturated with these gases are also indicated: (0) saturated with oxygen, ( x ) saturated with carbon dioxide. dioxide and with oxygen, exposed and unexposed 2100
ethyl alcohol solution. Jones1 found that, of the various organic solvents studied, rotenone in pyridine solution changed color most rapidly, while in the case of alcohol and benzene solutions the change is almost imperceptible. This suggests
[CONTRIBUTION FROM THE
to sunlight, showed that oxygen does not decompose rotenone in the dark. In light, however, there is marked decomposition, an effect which does not seem to be due appreciably to the presence of oxygen. PEIPINC,
DEPARTMENTS OF CHEMISTRY
CHINA
RECEIVED NOVEMBER 12, 1940
AND PHYSICS, ILLINOIS INSTITUTE OF
TECHNOLOGY 1
Raman Spectra of Acetylenes. V. Alkyl Acetylenes BY M. J. MURRAY AND FORREST F. CLEVELAND The main purpose of this series of papers' has been to determine what changes occur in the 2200 cm.-l region of the Raman spectra of acetylenic compounds when various groups are adjacent to the triple bond carbon and thus to obtain additional information in regard to the occurrence of more lines in this region for disubstituted than for monosubstituted acetylenes. The considerations given in paper I V indicate that some of the additional weak lines are due to isotopic molecules containing a carbon atom of mass thirteen, as JOURNAL, 60, 2664 (1938); 11, ibid., 61, 3546 (1939); (1) I, THIS IV, J . Chcm. Phys., 9,890 (1941.)
111, ibid., 62, 3185 (1940);
was suggested for dimethylacetylene by Glockler and Redrew2 and by C r a ~ f o r d . ~ An interesting observation* has been made in the case of 6-dodecyne. When this compound was allowed to stand in contact with air, an oxygen atom replaced the two hydrogen atoms on one of the carbon atoms adjacent to the triple bond carbon. The resultant 6-dodecynone-5 had only a single line a t 2212 (lo), whereas the parent 6(2) G. Glockler and Xf M Renfrew, tbid , 6, 340 (1938), Ih d , 6, 408 (1938). (3) B. L. Crawford, Jr., s b t d , 'I, 265 (1939) (4) M.J. Murray and Forrest F Cleveland, Tms JOURNAL. 63, 1363 (1941).
June, 1941
RAMAN SPECTRA OF ALKYLACETYLENES
1719
dodecyne had three lines a t 2231 (7), 2248 (2) and Raman displacements which correspond to those 2294 (4). Apparently the oxygen atom had previously observed for these compounds are set lowered the triple bond frequency so that it was in bold type in Table I. In general, the agreement no longer in sufficiently exact coincidence with is quite good. For 1-heptyne, however, the strong the overtone frequency (or frequencies) to pro- line listed by Magatg as 2940 was observed in the duce any observable resonance splitting. Or present study a t 2923. For 2-octyne, the line perhaps the removal of the hydrogen atoms from previously reported a t 280 was resolved into the the carbon atom removes or changes one or both of doublet 263, 296. On the other hand, the doublet the lower fundamentals involved in the resonance 963, 9i8 listed by Magat appeared as the single interaction. The fact that only one line has been line 9'72. Also for the latter compound, the line observed for other disubstituted acetylenes which previously reported as 2920(5) was found to be the have no hydrogen atoms on this carbon appears doublet 2916(6), 2939(10). The infra-red absorpto substantiate the latter view,lt5 although in one tion spectrum of 1-heptyne has been obtained by Lambert and Lecomte.lo case' a closely spaced doublet was observed. Frequencies below 2000 cm. -l.-The displaceThe present paper is a report of the Raman spectra of the alkyl acetylenes, 1-heptyne, 4- ments near 200 cm.-' probably correspond to demethoxy-1-butyne, 2-octyne, 3-octyneI 5-decyne, formation vibrations. They are more intense in the two monosubstituted acetylenes than in the 7-tetradecyne, and 9-octadecyne. five disubstituted acetylenes. This is in agreeExperimental ment with the results reported for other comThe acetylenes were supplied by Dr. G. F. Hennion of pounds in paper 111. The strong frequency near the University of Notre Dame and were prepared according to procedures previously described.8 The authors are 375 in the disubstituted acetylenes has a value near 335 in the monosubstituted acetylenes. This grateful for this assistance The apparatus and experimental technique were essen- agrees with Gredy's findings for a considerable tially the same as described in paper 11. The liquid number of acetylenes. As she observed, the 335 samples used in obtaining the spectra were purified immedifrequency disappears or is considerably weakened ately before exposure by distillation in a 30-cm., Podbielniak type, heated column. This was necessary since ex- when the carbon adjacent to the triple bond is perience indicated4 that many acetylenes upon standing tertiary. The fact that this frequency is strong for become contaminated by reaction with atmospheric oxygen the two monosubstituted acetylenes in the present to form ketones. The boiling points of the compounds paper and weak or absent for the five in paper 4-methoxy-lare as follows: I-heptyne, 98.4-98.6'; I11 adds weight to this conclusion. Crawford"'" butyne, 87.4-88.0'; 2-octyne, 135.5-137.5"; 3-octyne, ascribes the corresponding frequencies in methyl 132.5-132.8"; 5-decyne, 75' (23 inm.); 7-tetradecyne, 101 (3 mm.); 9-octadecyne, 163-1f.X4" (7 mm.). The slit and dimethylacetylene to bending of the CECwidth for the regular exposures was 0.08 mm. and 0.12 mm. CHa angle. The two monosubstituted acetylenes for the polarization exposures. also have a frequency near 630 cm.-' which was not observed for the five disubstituted comResults The results obtained for the seven compounds pounds. Following Crawford, this may be atare listed in Table I. The presence of strong tributed to the deformation frequency involving continuous background on spectrograms of 9-oc- the CrC-H angle. All seven compounds have tadecyne made impossible the measurement of a frequency near 815 cm.-' which is considerably depolarization factors and lines of low intensity polarized. Frequencies near 1040, 1075, 1115, 1300, 1440 for this compound. and 1460 are observed quite generally for comDiscussion pounds having hydrocarbon groups. The ones Previous Data.-Results were found in the at 1075, 1300 and 1460 may be attributed to literature only for l-heptyne7v8 and 2-0ctyne.~J chain frequencies.l2 Comparison with Craw(5) Blanche GrCdy, Comfit. rend., 196, 1119 (1933); 197, 327 ford's results for methyl and dimethylacetylene (1933); 198, 89,2254 (1934); 199, 294, 1129 (1934); Theses, Paris, indicates that the 1040 and 1440 frequencies, as 1935. ( 6 ) Hennion, cf a i . , J . 0% Chtm.,4, 1 (1937); THISJOURNAL, 69, 1310 (1937); 60, 1717 (1938); Pvoc. Indiaaa Acad. S c i , 41. 1113 (1938). (7) R. Courtel, Dipldme d'Lfudcs supdricurcs, Paria, 1932. (8) M.M.Bourguel and P. Daure, Compf.rend,, 190, 1288 (1930); Bull. SOC. chins., 47, 1849 (1830).
(9) M. Magat, "Tables annuelles de constants e t donnCes numeriques," Volume XI,Gauthier-Villars, Paris, 1936. (10) P. Lambert and J. Lecomte, Ann. phys., 10,503 (1938). (11) B. L. Crawford, Jr., J . Chcm. Phys.,8, 526 (1940). (12) Cf. S. E. Whitcomb, H. H. Nielsen and L. H, Thomas, W.,8, 148 (1940).
1720
M.J. MURRAY AND FORREST F. CLEVELAND
Vol. 63
TABLE1' ACETYLENES
RMdMi SPECTRA OF TBE ALKYL 1-Heptyne Au
212
I
p
3b 3b}o.7
309 2 } 0.7 336 5 353 3 434
4-Methoxy1-butyae Au I
*150
4b 205 3b
*338
6
507 1 548 1
p
0.7 0.7
AY
I
3-Octyne
Au
P
I
Au
P
5-Decyne I
p
7-Tettadecyne Au I p
9-Octadccyne Au I
372 4 0.7
364 2
0.8
169 l b 211 3 263 1 296 1
0.7 349 *375
418 3
1
2-Octyne
0.6
0.9 0.9
508 1 570 1
2 7 0.7
376 2
1 460 1
0.7
438
464 1 494 l b 556 l b
515 1 539 2
371 389 3 416 2 474 l b
}
0.6 0.8 0.7
547 l b
0.7
803 3 811 4
0.7 0.4
873 901 929 960
0.6 0.6 0.7 0.7
1434 1 0.91
567 1 626 3b 0.9 763 826
1 3 0.4
659 627 2b 2b} 0.7 822 4
0.5
685 1 803
677 1 781 1
771 1
1
P
812 2 849
846 1
1
944 1 962 1 974 1 1004 1 1035 2 P 1077 3 0.7 1111 4 0 . 7
P
980 1017 1047 1061 1116 1155
3 1 2 1 3 1
0.4 0.7 0.9 0.7
2064 0 2097 0 2118 10 0 . 4
2723 1 2861 6b 0 . 1 2908 8b 0.3 2925 8b 0.1 2964 4
0.9
3292 1 3309 2 medium
889 1
874 2 897 2 945 1
972
970 1
1335 1382 1422 1438 1454 1482 2064 2094 2118
2740 2828 2863 2893 2918 2939 [2965 2989 3296
3 2 2 5 3 2 0 0 10
1
1029 1 1064 2 0.7 1110 3 0.9
0.8
1273 1
0.8 0.8
1305 3 0.7 1335 3 0.7 1382 6 0 . 7
i
0.7
0.6
1064 4 1103 4
0.6
1299 2 1324 5
0.6
'}3
8 3 11 4
lb
weak
1457 3b
2198 0 2233 10 0.4 2256 1 2305 8 0 . 4 2731 1
2199 2235 2249 2296 2730
0 8 1 6 2
2872 2907 2927 2974
6 10 8 6
P
P
)0.7
1049 4 1104 1141 1204 1235 1295 1326
0.7
1051 1 1074 3b 0.6 1112 5 0 . 4
1075 2 1115 3
5 0.7 1 1 2
