[CONTRIBUTIOS FROM THE
DEPARTMENTS O F PHYSICS
AND CHEMISTRY,
FISKUXIVERSITY]
An Infrared Spectroscopic Study of the Carbonyl Stretching Frequency in Some Groups of Ketones and Quinones BY NELSONFUSON, MARIE-LOUISE JOSIEX
AND
ESSIE 11. SHELTON
RECEIVED NOVEMBER 9, 1953 The infrared spectra of over one hundred ketones and quinones have been measured in the six p region. The position of the carbonyl band is discussed as a function of one or more of the following: C=C conjugation, proximity of a cyclopropane ring, length of the aliphatic chain, branching of the chain, ring strain, Hammett's substituent constant and oxidationreduction potential. These results extend the ?cope of a study, being carried on in this Laboratory, of the effect of molecular environment upon the carbonyl frequency. spectra were obtained in dilute carbon tetrachloride soluIntroduction tion. The only exceptions were the diphenoquinones During recent years a very active interest has which, being in some cases insoluble in carbon tetrachloride, been taken in small variations of the carbonyl bond were studied in chloroform solution. The thickness of thc stretching frequency in the infrared spectrum of absorption cell employed was usually 1 mm. It was necessary to use 2-mm. and 3-mm. cells for some of the less soluhle groups of similar ketones and quinones. These compounds. studies have proved useful not only for compound Discussion identification purposes but also in order to obtain The results are presented in Table I. Each by experimental means a measure of particular factors in the molecular environment which have group of compounds will be discussed below in the been predicted theoretically on a qualitative order in which they appear in the table. a basis1-I4 as well as on a quantitative basis.15,16 A. Phenyl Ketones and Styryl Ketones.-In A more complete survey of the literature has been study of some phenyl ketones Mariella and Raube given e l ~ e w h e r e . ~The ~ , ~results ~ obtained in this have shown t h a t the cross conjugation effect upon the ultraviolet spectra is "damped out" for all but Laboratory thus f a r l * have ~ ~ ~ shown that v(C=O) may be correlated with molecular structure and phenyl propenyl ketone.18 In contrast t o this, we bond order. The new results in this present paper have found that the infrared carbonyl stretching include measurements, on several very different frequency of compounds of the type CeHs-CO-X sets of molecules, which will both enlarge the is markedly sensitive to changes in the substituent, experimental basis for conclusions previously decreasing with different X-substituents in the drawn, and present additional experimental data following order: saturated straight chain (XLI upon which more theoretical calculations can be through XLVIII), 1691 f 1 cm.-I; cyclanes with more than three carbons in the ring (111, IV, V), based. 1686 =t 1 cm.-l; -CH=CH-CH, (I), 1680 Experimental crn.-'; cyclopropane (11), 1677 cm.-I; and the The spectrometer used in this study was a single beam phenyl group (LXXXI), 1664 cm.-'. While the automatic recorder equipped with a large rock salt prism.'? Reproducibility was such that sharp bands between 1600 and 1800 cm.-l could be measured to within f l ern.-' or f 2 ~ m . - l . ~ 3Since intermolecular bonding effects and solvent interaction effects are so frequent for samples run in the solid state and in polar solvents, respectively, sample (1) R. S . Jones, V. Z. Williams, M. J. Whalen and K . Dohriner, THISJOURNAL, 70, 2024 (1948). (2) E. J. Hartwell, R. E. Richards and H . V.'. Thompson, J . Chenz. Soc., 1436 (1948). (3) R. S . Rassmussen, D. D. Tunicliff and R. R . Brattain, THIS J O U R N A L , 7 1 , 1068 (1949). (4) I. M. Hunsburger, i b i d . , 72, 5626 (1950). ( 5 ) h i . L. Josien and N. Fuson, C o m p f . r e n d . , 231, IS11 (1950). (6) 3f,L. Josien and N. Fuson, THISJ O U R N A L , 73, 478 (1951). (7) S . J. Leonard, H. S. Gutowsky, TI', J. hfiddleton and E. 51. Peterson, i b i d . , 74, 4070 (1952). (8) G. R. Clemo and D. G. I . Felton, J . Chem. Soc., 16.j8 (1932). (9) I M. Hunsburger, R. Ketcham and H. S . Gutowsky, THIS JOURNAL, 74, 4839 (1952). (10) E. D. Bergmann a n d S. Pinchas, J . chim. phrs., 49, 537 (1962). (11) h l . I,, Josien, N. Fuson and D. E. Pearsnn, Cotnpf r e n d . , 235, 1206 (1952). (12) .\I. I.. Josien and N. Fuson, Bull. soc. chiin. F r a ~ i c e ,19, 389 (1952). (13) Xi. I.. Josien, N. Fuson. J. R I . 1,ebas and T. L f . Gregory, J . Chenz. Phrs., 21, 331 (1953). (14) hl. L. Josien a n d N. Fuson, Compl. r e n d . , 236, 1879 (1953). (15) G. B. Bonino and E. Scrocco, A l l i . . V a d Li?zcie, Rend., Classe sci. fis.,6, 421 (1949, XIII); 8 , 183 (1950, 1'111); E. Scrocco and P. Chiorboli, ibid., 8 , 248 (1950, V I I I ) . (16) G. Berthier, B. Pullman and J. Pontis, J . chiin. phrs., 49, 367 (1952).
(17) If. L. Josien, S . Fuson and A. S. Cary, THISJOURNAL, 73, 444-5 (1951).
/CHz
infrared v(c=O) of CsH5-CO-CH
and that \CH,
of CF,H~-CO-C=Care shifted by different amounts, the ultraviolet spectral8 for these are identical. This is in contrast to the steroid case where the shifting effect of cyclopropane upon both ~ l t r a v i o l e and t ~ ~ infrared6 spectra is less than that of the unsaturated C=C link. The shifting effects of the cyclopropane ring upon the position of v(C=O) in phenyl ketones is slightly larger than that of the -C=C- group. This is the reverse of the situation found when the carbonyl carbon is a inember of a 6-carbon ring, i.e., unconjugated &ketone steroids,' 1ilO f 1 c i ~ ~ . - ~ ; i-~holestane-B-one,~~ i-androstandione," and carone,12 1689 i. 2 c1n-l; conjugated 3-ketone steroids,l 1677 f 3 cni.-'. The effect of the X-substituent of the C&I--CH=CH-CO-X group upon the carbonyl frequency is less easy to determine than in the previous case. The introduction of the conjugated C=C group in each compound adds another absorption band in the 1600 cm.-* region and in two of the six cases we studied we were not able t o resolve the v(C=C) and the v(C=O) bands. Nevertheless it is (18) R . P . Mariella and R. R. Raube, i b i d . , 74, 518 (1952). (19) I . M. Klotz. i b i d . , 66, 88 (1944).
Xfay 5 , 1%54
CARBONYL STRETCHING FREQVRNCY OF KETONESAND QUINONES
clear t h a t the v(C=O) of the styryl ketones when X is the cyclopropane ring (IX), (1685 cm.-l), is not as high as when the X-substituents are cyclanes with more than three carbons in the ring ( X and XI), (1690 =t 1 cm.-l). There is definite indication t h a t v(C=O) for the saturated straight chain substituent (VI) is still higher (ca. 1695 cm.-l).
The substitution of the styryl group for the phenyl group in each case raises the carbonyl frequency by about 5 cm.-’. B. Cyelopentenones and Cyc1ohexenones.-Because of previous studies made by Jones, et d.,’ and Leonard, et al.,7 we thought it would be of interest to make an infrared study of the set of
TABLE I KETONES AND QUINONES, TABULATED I N SOME CASES WITH THE CORRESPONDHAMMETT’S COSSTASTS,OXIDATIOS-REDUCTION POTENTIALS, AND/OR ULTRASONIC VELOCITIES
CARBONYL FREQUESCIES ING
O F SEVERAL S E T S O F
Other d a t a a s indicated
A.
u(C=O),h cm.-l
Y(C=C),
cm:’
Phenyl and styryl ketones 1 1 1
Phenyl propenyl ketone Phenyl cyclopropyl ketone Phenyl cyclobutyl ketone Phenyl cyclopentyl ketone Phenyl cyclohexyl ketone Styryl propyl ketone Styryl isopropyl ketone Styryl isobutyl ketone Styryl cyclopropyl ketone Styryl cyclobutyl ketone Styryl cyclohexyl ketone
B. XI1 XI11 XIY XY SYI XVII
Source4
Name
Number
I I1 I11 IV V 1 7I VI I YIII IX S SI
1 1 1 1 1 1 1
1680 1677 1686 1687 1686 (1710-1670)’ 1692 1669 (170n-i660)~ 1662 1685 1691 1667 1663 1690
2 2 2 2 2
1712 1720 1694 1699 1697
2 2 2 2 2 2
1699 1702 1688 1690 1664 1664
3 3
1641 1649
1
Cyclopetitenones and cyclohexenones
XYIII XIS XX XXI XXII
4-Hydroxy-4,3-diphenyl-2-methyl-A2-cyclopen tenone 4-Hydroxy-4,3-diphenyl-A2-cyclopentenone 5-Benzylidene-3-methyl-2-propyl- A*-cyclopen tenone 5-Benzylidene-3-phenyl-A2-cyclopentenone 5-Benzylider1e-4-hydroxy-4,,7-diphenyl-~~-cyclopenteno1ie 5-Benzylidene-4-hydroxy-4,3-tiiphenyl-2-methyl-A~-cyc~opentenone 5-Benz~lidene-4-hydroxy-4,3,2-triphenyl-A~-cyc~opentenone 5-Isopropylidene-4-hydroxy-4,3-diphenyl-A2-cyclopen tenone 2,3,6,7-Tetraphenyl-A2~6~8-cycloindatrienone 6-Benzylidene-6,3-dimethyl-A2-cyclohexenone 6-Benzylidene-5,5,3-trimethyl-A2-cyclohexenone
XXIII SXIV
a-Tocopherylquinone P-Tocopherylquinone
C. Tocopherylquinones
E , d volt
D. XXV XXYI XXVII XXYIII XSIX
XSS XXXI XXXII XXXIII SXXIY XXXV
Methyl-l,2-benzanthraquinones
1,2-Benzanthraquinone 3-Methyl- 1,2-benzanthraquinone 4-Methyl-I,2-benzanthraquinone 5-Methyl-l,2-benzanthraquinone 6-Methyl-1,2-benzanthraquinonc 7-Methyl-l,2-benzanthraquinone 2’-Methyl-l,2-benzanthraquinone 3’-Methyl-l,2-benzanthraquinone 4’-Methyl-l,2-benzanthraquinone 5,6-Dimethyl-l,2-benzanthraquinone 6,7-Dimethyl-l,2-benzanthraquinone
4 4 4 4 4 4 4 4 4 4 4
1670 1670 1670 1668 1670 1670 1670 1670 1671 1668 1670
E. Diphenoquinones XXXYI XXXVII XXXVIII XXXIX
XI,
2527
Diphenoquinone (red form) Diphenoquinone (gold form) 3,5,3’,5’-Tetramethyldiphenoquinone 3,5,3 ’,5’-Tetra-&butyldiphenoquinone 3,5,3’,5’-Tetrachlorodiphenoquinone
1635 1635 1637 1634 1646
0.224 .208 ,177 ,168 ,211 ,209 ,213 ,213 ,209 ,200
N.Fi,son., ?\I.-L.JOSIEN
2528
AND
E. 11. SITELTON
TABLE I (Continued) Other d a t a as Number
XLI XLII XLLII XLIV XLV XLVI XLVII XLT’III XLIX L LI LII LIII LIV LV
LVI LT’II
Name
Source5
F. Alkyl phenyl and p-xylyl alkyl ketones Methyl phenyl ketone (acetophenone) 6 6 Ethyl phenyl ketone 6 Butyl phenyl ketone 6 Amyl phenyl ketone 6 Hexyl phenyl ketone 6 Heptyl phenyl ketone 6 Octyl phenyl ketone 6 Xonyl phenyl ketone 6 Methyl p-xylyl ketone 0 Ethyl p-xylyl ketone 0 Propyl p-xylyl ketone 6 Butyl p-xylyl ketone G Amyl p-xylyl ketone 6 Hexyl p-xylyl ketone 6 Heptyl p-xylyl ketone 6 Octyl p-xylyl ketone 6 Nonyl p-xylyl ketone
u(C=O).b ,cm.-‘
1692 1692 1690 1690 1690 1690 1691 1690 1690 1691 1689 1690 1690 1690 1690 1689 1690
indicated
V . # m. see.-’
1463 1456 1434 1433 143G 1437 1445 1451 1445 1434 1420 1414 1414 1416 1421 1428 1430 E , I volt
G. LVIII LIX LX LXI LXII LXIII LXIV LXV LXVI LXVII LXT‘III LXIX LXX LXXI LXXII LXXIII
Alkyl alkyl ketones
2-Propanone (methyl methyl) 2-Butanone (methyl ethyl) 3-Methyl-2-butanone (methyl isopropyl) 2-Pentanone (methyl propyl) 4-Methyl-2-pentanone (methyl isobutyl) 2-Heptanone (methyl amyl) 3-Pentanone (ethyl ethyl) 3-Hexanone (ethyl propyl) 3-Heptanone (ethyl butyl) 3-Octanone (ethyl amyl) 2-Heptanone (propyl propyl) 2,4-Dimethyl-2-pentanorie (di-isopropyl) 4-Sonanone (propyl amyl) 5-Nonanone (butyl butyl) 5-Decanone (butyl amyl) 6-Undecanone (amyl amyl)
rn
i
c
I
8
”I c
i
” I
0 0 G 0,7 6 (i
0,7 6 0
1719 1720 1718 1720 1720 1719 1717 1718 1717 1717 1716 1713 1715 1716 1715 171G
0.329 .I23 .122 ,122 ,122 ,121 ,118
,117 ,116 ,117 ,110 ,109 ,109 ,101 ,103
,095 Additional ‘C=O), cn1.
H.
LXXIV LXXV LXXVI LXXVII LX XI’I I I LXXIS
-1
Epoxy ketones
1,4-A-aphthoquinone 1,4-Naphthoquinone-2,3-osirle Progesteroneh Oxido-progesterone Pregnenolone acetate Oniclo-pregnenolone acetate
10 11
I1 11 11
lBft50 1710 1707 1709 1708 1705
1681’ 1680i 1738’ 1748’ E:,!+ volt
Substituted lmizophenones 4,4’-Di-(dimethylamino)-benzophenone 4-Aminobenzophenone 4,4’-Dimethosybenzophenoile 4,4’-Dimethylbenzophenone 4-hlethoxybenzopherione 4-t-Bu tylbenzophenone 4-hlcthylbenzophenone Benzophenone 4-Chloro-l’-tnethylbenzophenone 4-Chlorobenzophenone 4-Bromobenzophenone 3-Bromobenzophenone l,l’-DichIorobenLophenone ~,~’-~ibrotnobet~zo~~l~~t~~~~~e
01
I.
LXXX LXXXI LXXXII LXXXIII LXXXIV LXXXV LXXXT‘I LSSX\’II LXSXVI II LSSX I S SC XCI XCII SCIII
c)
1689 1631 1 6.55 16.59
9
1fi.i5
c)
1664 1661 1R i l l 1667 1RRfl 10R.i lRfi9 1n;o 1(i73
c) c)
0
0 9 0 r)
0 0 9 !I
-1.161 - 1 ,260 - 1.187 -1.104 - 1.10R -1.165 - 1.140 -1.10’7 - 1 .09:3 -1.051 -1.021 - 1 00’7 - 0 H1*3
--O.tx - ..ix - .340
-
,268 ,197
,170 .0 ,057 ,227 ,232 ,391 ,454 ,782
\lay 5 , 1954
CARBONYL STRETCTIINC
FREQUENCY O F KETONFS
2.529
AND (2UIh'Oh'ES
TABLE I (Continued) Number
Source5
Name
v(C=O), b cm.-'
Other data as indicated cm
J. Substituted acetophenones XCIV XCV XCVI LXI XCVII XCVIII
XCIX C CI CII
p- Aminoacetophenones p-Hydroxyacetophenone p-Methoxyacetophenone Acetophenone p-Chloroacetophenone p-Bromoacetophenone m-Nitroacetophenone p-hTitroacetophenone p- Acetoxyacetophenone p- Acetylaminoacetophenone
12 12 12
6 12 12 12 12 12 12
1677 1086 1684 1692 1692 1693 1701 1702 1691 1686
-0.66 - ,317 - ,268
.o .227 .232 .710 .778"
(1) R. P. tariella, Loyola Univ., Chicago, Ill. (compounds re-purified by C. I.Hill, Tenn. A & I State Univ., Nashville, Tenn.). (2) 1. S . French, Wellesley College, Wellesley, Mass. (compounds re-purified by C. M. Hill, Tenn. A & I State Univ., Nash\ le, Tenn.). (3) M. Farber, Cornel1 Univ. Medical College, New York, N. Y. (4) J. Iball, University College, Dundee, Sco and. ( 5 ) H. Hart, Michigan State College, E. Lansing, Mich. (6) R. T. Lagemann, Vanderbilt Univ., Nashville, Tenn. (7) Commercial product (Fisher Scientific Co.). (8) Commercial product (Eastman Kodak Co.). (9).D. E. Pearson, Vanderbelt Univ., Nashville, Tenn. (IO) L. F. Fieser, Harvard Univ., Cambridge, Mass. (11) P. L. Julian, Research Dept., Soya Products Division of the Glidden Co., Chicago, Ill. (12) A. H. Soloway, Sloan-Kettering All frequencies were measured for compounds in dilute solution in carbon Institute for Cancer Research, New York, N. Y. The C=O and tetrachloride with the exception of the diphenoquinones which were studied in dilute chloroform solution. C=C absorption bands were not sufficiently resolved in this case to justify assigning frequencies. The numbers in parentheses give the general location and width of the unresolved doublet. * Oxidation-reduction potentials taken from ref. 22. f Oxidation-reduction potentials taken from ref. 26. 0 Carbonyl frequency taken c Ultrasonic velocities taken from ref. 24. Dilute CS, solution frequencies of 1708 and 1677 cm.+ are given for this compound in ref. 1. This lower from ref. 13. frequency of the pair is assigned to the conjugated 3-keto carbonyl group (see ref. 1). f This higher frequency of the pair is assigned to the acetate v(C=O) (see ref. 1). * Oxidation-reduction potentials taken from ref. 30. I Hammett substituent 73, 5836 (1951), confirm the p-methyl constants taken from ref. 31, p. 188. C. C. Price and D. C. Lincoln, THISJOURNAL, Hammett substituent constants taken from ref. 31 except that for p-hydroxy which and p-t-butyl values almost exactly. Hammett (ref. 31, p. 188) is as calculated by Jaffe in ref. 35. No values of u were found for p-acetoxy or p-acetylamino. Lists two U-values for the +nitro substituent. The value used here is the one which he states is "for all benzene derivatives except those of aniline and phenol."
cyclopentenones and cyclohexenones recently studied in the ultraviolet by French.2o They proved to be a good example of the sensitivity of the infrared carbonyl frequency to molecular structure. The carbonyl frequency of the endo-conjugated cyclopentenones (XI1 and X I I I ) (1716 + 4 cm.-1) is close to the value of 1716 cm.-' found for a,/?-conjugated cyclopentenones.' Of the endoand exo-con jugated cyclopentenones those in which the exo-unsaturated bond terminates in a CsH6 group (XIV through XVIII) have a carbonyl frequency of 1698 f 4 cm.-l, that for the two others not having the benzene ring termination (XIX crn.-l. Finally the carand X X ) being 1BS9 bonyl frequency of the endo- and exo-conjugated cyclohexenones (XXI and X X I I ) is I664 cm.-'. C. Tocophery1quinones.-Rosenkrantz and Milhorst?' made an infrared study of tocopherylquinones in the solid state. They suggested that the low values of v(C=O)which they found were a result of hydrogen bonding. This would require a chelation effect resulting from the formation of an eight-atom ring, an effect which has not yet been substantiated in the literature. We have been able to obtain relatively sharp bands a t 1641 and 1649 cm.-l for a-tocopherylquinone and ptocopherylquinone, respectively, in carbon tetrachloride solution. These bands, which we have assigned to v(C=O),appear to be free from overlap with v(C=C) bands. We disagree with Rosenkrantz's hypothesis, suggesting rather that these low frequencies are produced by an induction effect (20) H . S. French, THIS JOURNAL, 7 4 , 514 (1952). (21) H. Rosenkrantz and A. T. Milhorat, J. B i d . Chem., 187, 83 (1950).
resulting from the large number of substituents attached directly to the quinone ring itself. An example of the strong effect of substituents on the quinone ring is to be found13in the following series: l14-naphthoquinone (1675 cm.-l) ; 2,3-dimethyl1,4-naphthoquinone(1660cm. -l), Av = - 15 cm. -I; and 2,3-dichloro-l,4-naphthoquinone (1687 cm.-l), Av = + I 2 cm.-l. For a corresponding l14-benzoquinone series with four substituents on the quinone ring, one might predict, by analogy, t h a t the frequency shifts should be about double those for the 2,3-disubstituted naphthoquinone ring. This suggestion is borne out e~perimentally,'~ for the frequency shift from 1,4-benzoquinone (1667cm.-l) to 2,3,4,5-tetrachlorobenzoquinone (1695 cm.-l) is Av = +28 cm.-l. Thus we predict t h a t the frequency of 2,3,5,6-tetramethylhenzoquinoneshould he ca. 1667 - ( 2 X 15) or ca. 1637 cm.-1,21aand that the frequency of 2,3,5-trimethylbenzoquinone,decreased about 75y0 as much, should be ca. 1645 cm. -I. The CY- and p-tocopherylquinones, which are rather similar to tetramethyl- and trimethyl1,4-benzoquinones, have frequencies (1641 and 1649 cm.-', respectively) which are thus quite close to those predicted. D. Methyl Benzanthraquin0nes.-The variation in oxidation-reduction potential is very small for the set of methyl benzanthraquinone isomers studied by Iba11.22 Table I shows that for these compounds v(C=O) is if anything an increasing (21a) One of us (M. L. J.) recently obtained some 2,3,4,.5-tetramethylbenzoquinone from Dr. Souchay of the Sorbonne. Its u(C=O) (measured at the Universitb de Bordeaux) i s 1641 cm.-1. This tits rather closely our prediction. (22) J. Iball, A m . J. Cancer, 98, 372 (1940).
function of the oxidation-reduction potential, that the ultrasonic velocity in a series of alkyl although the shifts in b(C=O) are likewise too phenyl ketones passes through a inininium for amyl small to be used as a basis upon which to make phenyl ketone. They found that this minimum any precise correlation. velocity also occurs for the same alkyl chain length E. Diphenoquin0nes.-Detroit and Hart's re- in p-xylyl alkyl ketones. B study of the infrared cent study of the effect of substitution on the ultra- spectrum of these two series of compounds shows violet absorption spectrum of diphen~quinone'~ that the carbonyl frequency of the former series stimulated us t o make a parallel infrared study. (XLI-XLVIII) is constant a t 1691 f 1 cm-', that Diphenoquinone in the solid state exists in two of the latter series (XLIX-LVII) being constant a t crystalline modifications,?3 the red modification 1690 + 1 crn.-'. Thus the carbonyl frequency being much more soluble in chloroform than the remains unaffected by the peculiarity of these two gold. (We found the Kujol mull spectra of the series of molecules, whatever it is, which is respoiitwo forms to be practically identical.) Dipheno- sible for the appearance of the ultrasonic minima. G. Alkyl Alkyl Ketones.-Syrkin and Dyatkina quinone itself and some of the substituted diphenoquinones being insoluble in non-polar solvents such state that "in a series of saturated ketones the as carbon tetrachloride and carbon disulfide, all value for the (carbonyl) frequency of 1710 cm.-' rethis group of compounds were run in the polar mains constant irrespective of the chain length. . . ' ' ? 5 solvent, chloroform. Jones, et al.,' have shown for Figure I is a graph of the v(C=O) of the alkyl alkyl steroids that chloroform solution carbonyl frequen- ketones obtained in this study vs. the corresponding cies ranged from 0 t o 22 cm.-l lower than the cor- oxidation-reduction potentials.26 The v(C=O) is, responding carbon tetrachloride solution frequen- again, an increasing function of the potentials, the cies. Similar results have been recorded for qui- slope of the curve being about 2 cm.-'/centivolt. nones.I2 The amount of the shift is as yet unpre- This result shows t h a t Syrkin and Dyatkina's dictable. Thus it is not possible to draw signifi- statement should be considered as only afirst approxcant conclusions between the chloroform solution imation, useful when comparing saturated ketone diphenoquinone results and carbon tetrachloride frequencies with other carbonyl frequencies. Our solution spectra of other groups of compounds con- results in Table I show that for a symmetrical taining the carbonyl group. I t is very possible, chain ketone v(C=O) decreases from 1T19 cm:-' for also, that chloroform solution frequencies of the methyl methyl ketone (LVIII) to 1 i 1 3 c m - l for different substituted diphenoquinones are variously amyl amyl ketone (LXXIII) as the chain length ineffected by interaction with the polar solvent. creases. Because of the small frequency shift we n'ith the preceding statement in mind as a reserva- would not put as much emphasis upon this result tion, it may be pointed out that the carbonyl fre- as we have if it had not been for the rather large quency of diphenoquinone (XXXVI and XXXVII) number of ketones available, thus giving statistical (1633 cm.-l) is not shifted when the hydrogens on weight to the study. An examination of Hartwell, Richards and the four carbons adjacent to the carbonyl groups are replaced by methyl or t-butyl groups. The Thompson's vapor data on some of these comtetrachloro substitution, however, increases the pounds? shows that in the vapor state the decrease in v(C=O) for the long chain ketones is 9 c m - ' frequency by 11 cm.-'. F. Alkyl Phenyl Ketones and p-Xylyl Alkyl this being larger than the corresponding decrease Ketones.-Lagemann, et nl.,24have recently shown in the solution state. This is to be expected because of the dielectric constant effect.?' For the non-symmetrical tnethyl alkyl ketone series ,725 (LVIII-LXIII) the v(C=O) in solution appears to be constant a t 1719 c m - I as the chain increases. i Hartwell, et al.,'s data for gaseous CH3-CO-II ke5. 0 tones show a decrease of 4 cm.-' as R increases from -CH3 to -(CHs)3CH3. Since this is about 1720 0 half that for the symmetrical gaseous ketones, by z W analogy, the shift in the solution case should be 3 O only about 2 c ~ i i . - ~which , is within the limit of erW ror of our ineasurenients and so cannot bc rleE 1715 tectecl. This is undoubtedly true also for the dkyl phenyl ketones (XLI-XLVIII) and p-xylyl alkyl ketones (XLIX-LTrII) which show only the barest
1
9
.
Y
.
1710
t
E 0.10 0.11 0.12 0.13
0.09
OXIDATION
REDUCTION POTENTIAL (CENTIVOLTSZ
Fig. 1 .-Carbonyl frcqueiicy 1 ' s . osidation-rcdiiction potential for alkyl alkyl ketones i n carbon tctr:ichloritle solution. (23) %'. J. Detroit and H . H a r t , THISJ O U R S A L , 74, 5215 (lS52). (21) R. T. Lagemann, R. Gwin, C. T. Lester, J , R . Proffitt a n d E. C. Siiratt, i b i d . , 73, 3213 (1950)
(2.;) U.K Syrkin and M E Dyatkina, "Structure of LIolecnles ani1 the Chemical Ron
