RICHARD D. CAMPBELL AND NORMAN H. CROMWELL
3456
VOl. 79
TABLE I1 I'ROI'ER1'IES
O F E P O X I D E S C O S T A I S I S C I-ITDROXTI, GROUPS
13.1>., Cumpound
,. 1 ctrah) tirop~raii-2-irietIi~ciiol 3-l~~dros?.tetr~ili?.drofuraii
OC.
Prc.;?., mm.
,57
4.2
110
5.6
C a r b o n , 70 Calcd. Found
Hydrogen Calcd. Found
1.4561
62. 1
62.2 62.1
1 0 ,2
1.4493
54.6
54.6 34.8 54.9 62.0 62.4 58.6 58.8
9.1
%260
3-Etliyl-3-oxetane1nethanoi
84
2.8
1.4517
G2.1
3-hIethyl-3-oxetaiieinethanol
80
4 0
1.4449
58.8
3,3-Osetaiieditnetliaii~l
153
3.5
(Solid)
3-Ethyl-3-oxetanemethanol from Trimethylolpropane. -.4 mixture of 268 g. of trimethylolpropane (2.0 moles), 236 g. of diethyl carbonate (2.0 moles) and 0.10 g. of potassium hydroxide dissolved in 5 ml. of absolute alcohol was refluxed until pot temperature was below 105" (15 minutes), and the mixture was distilled keeping the head temperature 76-78'. Distillation was continued until the pot temperature was 145O, and then the pressure was reduced gradually to 50 mm., maintaining the pot temperature a t 140-150". The weight of distillate was 179 g. (theory 184 g. alcohol). Upon heating above 180°, carbon dioxide evolution was
[COSTRIBUTIOS FROM THE .\VERY
50.9
50.4 50.5
10.4 9.8
10.2 10.6 10.2 9.0 9.3 0.3 10.2 10.4 9.9 9.9
8.5
5.7 8.5
I I y d I o h y l xu. Calcd. Found
481
486 487
G38
629
632 484
mi 483
549 951
543 546 907 BOG
rapid atid most of the material distilled a t 19O-21Oc pot temperature, 90-140" head temperature and 50-90 iiini. pressure. Kear the end the pressure became 2-10 mm. ant1 the head temperature rose. Redistillatioil through :in efficient column gave: 13.4 g., b.p. 84-86' a t 3.5 niin.; 136.6 g., b.p. 84-81.5 a t 2.8 inm.; -34.4 g., b . p . 84.585.5 a t 2.8 mm.; 26.1 g., residue. The main fraction was anal>-tically pure 3-ethy1-3-oaetnnemethanol, and from the residue analytically pure triiriethylolpropane was obtained by distillation. I~ILMISGTON, DELAR'ARE
LABORATORY, UNIVERSITY
O F NEBRASKA]
Endocyclic a,P-Unsaturated Ketones. V1.I Ultraviolet and Infrared Absorption Spectra and Resonance Stabilizations B Y RICHARD D.
CllMPBELL2 AND
NORMAN H.
CROhZWELL3
RECEIVED MARCH1, 1957 Sew data :ire presented for the ultraviolet absorption spectra of thirteen ketones. These coinpounds are iiieiiibers of three series, via., l,l-dimethyl-2-keto-1,2-dihydronaphthalene (l,l-dimethyl-2(1H)-naphthalenone) (II), 4,4-dimethyl-lketo-1,4-dih)~droiiaphthalene(1,4-dimethyl-l-(4H)-naphthalenone) (I), and perinaphthenone-7 (141H)-benzonaphthenone) !III), With previously reported data for eight related compounds, t h e spectra are discussed with respect t o resoiiance stabilirdtions, effect of nature and position of substituents, and type of conjugation. New infrared spectral data are prcwited for twenty-one ketones in the three series. These results are discussed with respect t o the Snme factors.
(1) For paper KO.V, see, N. H. Cromwell a n d R. D. Campbell, J . O r g . Chem., 22, in press (1967).
double bonds on the spectra of a,@-tiiisaturatr.cl ketones has been discussedS6 It was o b ~ e r v e d ~ .that ' , ~ various substituents on the CY- or 6-carbon atom of the a#-unsaturated ketone system have a bathochromic effect on the ultraviolet absorption bands. The extent of the shift varied with the nature of the substituent, and the position of attachment. Resonance forms mere suggested for the chromophores responsible for the characteristic bands.4 The importance of chelation in the P-hydroxy7 and &amino ketones was d i s c ~ s s e d . ~Since such chelation or ionic inter.action is impossible in the endocyclic series, it seemed of considerable interest to study these endocyclic compounds. The compounds used in these studies are all of
(2) Du P o n t Teaching Fellow, 1954-1955. Ph.D. Thesis, Univprsity of Nebraska, 1956. (3) T o whom inquiries regarding this article should be addressed. (4) N. H. Cromwell a n d W. R. Watson, J . Org. Cheiii., 14, 411 (1949). (5) \V,B . Black a n d R. E,L u t z , THISJ o r r R ? 4 % 1 . , 77, i l 3 l ( I l l i 5 ) .
( 6 ) H. S. French a n d L. Wiley, ibid., 71, 3702 (194s); H. S. French, i b i d . , 74, 514 (1952). ( 7 ) K. Bowden, E. .4.Brallde and I;. X . I 1 !1.I l l , J o h t i iViIcy :tnil Son%,Tnc , S e \ r Vork, S Y , 10.5.3, Chapter 2 .
If1
A
1
;
11
A+?/oe
I
1 + I
D
'VV E
aromatic ring, as forms D and E indicate. The two forms D are expected to be more stable due to the retention of the Kekule ring. In the three forms E the Kekule structure is absent. However, the long wave length band of VI1 is nearer the visible and more intense than the benzoyl band of IV or the principal band of the naphthalene nucleus.20 Hence this band of VI1 must involve an important contribution from forins E, as wcll as forms D. Further evidence for the nature of the resonance stabilizations possible in these three series of ketones (I, I1 and 111) is revealed in the spectra of their a-bromo derivatives VIIT, XI1 and XV. respectively. Introduction of the a-bromo substituent onto ketone I1 causes a bathochromic shift of 160 A. for the long wave length band. The a-bromo substituent wa? reportedS to cause a bathochromic shift of 80-120 A. for a,@-unsaturated ketones. The shift indicates that the bromine atom lends more resonance stabilization to the excited state than to the ground state. In addition to forms indicated by A, forms F and G might be stabilizing the excited state by supporting part of the positive charge. One may consider two or more molecular orbitals simultaneously encompassing the systems described by A, F and C , ~
(19) L. N. Ferguson. "Electronic Structures of Organic hloleculea," Prentice-Hall, i i e w York, N. Y., 1952, C h a p t e r 9. (20) R. A . Fiiedel a n d hf. Orchin, "Ultraviolet Spectra of Aromatic Compounrls," John X'ilry anti Son-, Tnc., Nri, Y ~ r k S. , X-., I c l i l
RICHARD D. CAMPBELL AND NORMAN H. CROMWELL
3458
Vol. 70
TABLEI SUMMARY OF ULTRAVIOLET AND INFRARED ABSORPTION SPECTRA OF ENDOCSCLIC UNSATURATED KETONES
q
Structure
NO.
Sourceo
X(A.)
Ultraviolet max. b AXd
x
10-
Infrared C=O bandC Wave number, cm. --I CC!4 Avd
Nujol
A
0
A = H
I
11
A = Br
VI11
11
A = NC141180
1);
Ob
A = OCHa
x
1
n
= OH
{$
SI
IV
9b
11
2300 (2520)" 2870 2970 2250 2500 2560 (2680) 3010 2480 2890 2990 3250 2200 (2260) 2500 2810 2290 254u 2930
2430' 2860 2950
200
260 50 180 20 20
200
240 60
10.7 8.8 2.2 1.9 5.0 10.9 11.0 6.6 1.8 13.0 2.6 2.7 1.9 6.6 5.2 9.7 0.0 6.7 10.0 7.7
I657
*.
8
1073
1(jiiX
1655
- 3
1ti70
1649
1685'
ll.G
- 10 - 20
lF65
5
-If\
20
1.4 1.1
0
/ A B A = B = H
.4 = Br I3 = €I
XI
1
XI I
1
SI11
XlV
1
1
2450
!)0-150
15.4 lij.8 10.2 10.1 10.4 11.7 12.6 13.2 9.1 15.0
3530 222r ) 2430
.?XI
8.8
3350
130 150 3 50
7.1 12.8 14.5 9.4
'"40h 2720
- 300 -280
2300" 2360 2940 3000 2100 2350 2420 3160 2200
2510
v
12, 1
50 60 160
0.3s 0.36
1058"
1662
7 678
1G.52
1670
1fi42
I Mi3
1710q
1713
16
ENDOCYCLIC UNSATURATED KETONES
July 5, 1957
3459
TABLE I (Continued) Structure
\
h70.
Source0
UA.)
Ultraviolet max. b A Ad
e X 10-8
Infrared C=O bande Wave number, cm. -1 Sujol cc14 A d
62
1714
1724
1636'
1646
1640
1650
1637k
1640
- 6
1633k
1640
- 6
1630
- 16
Br
I
B A = B = H
I11
14
A = Br B = H
XV
16
X = H B = NC~HBO
XVII
A = OH B = H
XVIII
A = OH B = H
A = H B = OH
XVIII
XIX
10
10
10
10
2450' (2600) (3400) 3550 3800 2100 2200 (2420) 2520 2600 3260 3420 3570 3810 (3920) 2360k 2680 2740 3360 3460 3620 4520 2400k 3440 3660 2370" (2810) 2590 (2700) 3160 3350 3510 4200 21001 2380 (2530) 2600 (2700) 3290 3480 3630 4260 2110f 2280 3330 3520 (3880)
20 20 10
-
90
- 90 - 180 -110 - 140
21.5 9.5 7.5 11.5 9.0 15.0 10.6 15.5 20.1 16.1 4.1 6.2 10.7 8.9 8.7 21.0 15.0 15.3 4.7 5.1 5 0 5.2 27.0 14.0 12.0
4
- 200 -290
(- 70) (-170)
- 220 - 280
20.2 17.8 12.8 14.0 11.6 5.7 5.4 6.9 5.3 23.0 22.7 11.3 10.4 4.5
1626
- 10
RICHARD D. CAXPBELL AND KOXMAN H. CROMWELI,
3430
Vol. 79
TABLE I (Continued) btructure
NO.
SHCGHll
-4
sx
VI1
Source*
10
15
1 2400k 2700 3300 3i00 5000
Ultra1 iolet max b
2400'
2450 3170 3310
('? a
XXI
13
/
fyYO
dJ'SC
XSII
10
AXd
- 250 - 100
-
50 - 100 - 380 - 450
Infrared C=O b a n d C W a v e number, cm.-' CCla
X 10-3
A-ujol
24 27 4 3 5
1632k
1622
- 24
;
19 18 6 5
2 5 5 5
16777
1690
44
1676
1683
37
1685j
1683
37
0
A d
4 6 0
0.4
2430' 2450 3200 3350
- 350 -450
9.5 8.2 8 .0
2470' 3200 3350
- 350 - 450
19.0 7.2 6.6
61% 11
Sumbers are literature references which appear throughout the article. -\ll samples were freshly purified according to the literature directions. The ultraviolet-visible spectra were determined using a Cary recording spectrophotometer, Model 11 MS,according to the manufacturer's directions. The sample solutions were freshly prepared using 2,2,4-trito 10-5 AT). The infrared spectra were methylpentane (Eastman Kodak spectra grade) in suitable concentration determined between 700 and 4000 cm.-l using a Perkin-Elmer Model 21 double-beam infrared spectrophotometer. The Sujol mulls (or pure liquid) were made up to give good resolution. The determinations using carbon tetrachloride solutions The values wcre carried out in 1.0 mm. or 0.1 mm. matched cells. The concentration of these solutions was 12 mg./ml. for A i and AV were calculated by subtracting the value for the parent ketone from that of the derivative for the correspondf Solvent was absolute ing band, and in corresponding medium where possible. e Values in parentheses are shoulders. methanol. Pure liquid. See footnote c. Beckman DU spectrophotometer. i Data from ref. 9a. j Data from ref. 17. Satd. s o h . Data from ref. 10. 1 Data from -4. Hassner. Ph.D. Thesis, University of Sebr., 1956.
made by Nussbaum, et al.,8 applies to these compounds : the a-bromo substituent causes a greater shift in the spectrum of phenyl vinyl ketones (viz., I) than of P-styryl ketones (viz.,11), see Table I. Introduction of the bromine atom onto the aposition of ketqne 111 results in a bathochroniic 13r shift of 10-20 A. of the long wave length bands (3300-4000 A.). This indicates that the bromine F G atom hardly makes any more resonance contribuThe broiiiiiie substituent contributes in some such tion to the stability of the excited state than of the indirect manner to the resonance stabilization of ground state. As indicated before, the positive the excited state. It has been pointed out8 charge of the polarized form B already is supported that valence-bond structures such as A, F and G by extensive delocalization both in the ground state cannot be written to show the resonance contribu- and in the excited state. tion of the bromine atom to the polarized carbonyl An additional triplet band (2300-2800 B.) system. This problem is present in any cross con- appears in the spectrum of XV. This triplet is jugated system. characteristic of the a-substituted perinaphtheIntroduction of the a-bromo substituent onto nones to be mentioned later. Absorption in ketone I was reporteda to give a bathochromic this region is characteristic of benzoyl polarizashift of 140 A.,using ethanol as solvent. The tions stabilized by additional resonance intershift observe4 by us using isooctane as solvent was actions.',5,20 Canonical forms H, J and K, repre200 or Xi0 A., depending on assignment of the split peak for VIII (2500, 2560 A.). Only one peak was reported by Nussbaum, et aZ.,8 for VI11 a t 2560 4 . in ethanol; the bands for I in ethanol m d isooctane are 2420 and 2300 A., respectively. The solvent effect is as expected.20 This solvent effect is greater with the parent ketone I than with the a-bromo derivative VIII. A generalization H J without conflict with the Pauli exclusion principle.
I I1 I/
July 5, 1957
ENDOCYCLIC UNSATURATED KETONES
3461
Introduction of the morpholino, methoxy or sent such polarizations in XV. Although the two polarized molecular orbitals implied by J cannot hydroxy groups into the a-position of ketone I interact by first-order conjugation, electrostatic results in bathochromic shifts of 180, 200 and interaction is expected to contribute some stabiliza- 240 Ad, respectively, for the strong band (2300tion to the polar form. One might expect that 2800 A.), indicating resonance stabilization of the the three forms K are of very nearly the same excited state with respect to the ground state. The absorption band of I in the 2700-3100 A. energy, i.e., degenerate states. Under the electrostatic influence of polarization H (implied in J), region is shifted 20-60 A. to longer wave length the degeneracy of K gives rise to the triplet (Stark (except in X) and increased in intensity by the asubstituents. The resonance stabilization of the effect)31in the 2300-2800 A. region. The ultraviolet spectra of the derivatives of I11 excited state may be due to ionic forms described4 with N-cyclohexylamino, morpholino and hydroxyl for similar compounds. Since this is a crossgroups in the a-position (XX, XVI and XVIII, conjugated system, i t is difficult to describe a respectively) are nearly identical.lo These sub- polarization in which both the carbonyl oxygen stituents result in a considerable decrea2e in the and a-substituent simultaneously carry a charge, intensity of absorption in the 3000-4005 A. region, but some such interaction seems to occur.4 Since the electronic system of I1 is more closely and a hypsochromic shift of 90-290 A. for these absorption maxima. This may indicate resonance related to benzalacetone, chalcone and ketone I11 interaction and stabilization in the ground state than to I, the effects of substituents on the spectrum of I1 should follow this relationship. The to a greater extent than in the excited state. Two bands appear in the spectrum of the a- P-morpholino and P-hydroxx groups cause bathosubstituted derivatives of 111, and not in the chromic shifts (530 and 350 A., respectively) of the spectrum of 111. One of these, in the 2300-2800 A. cinnamoyl band of 11. This is consistent with the region, is the triplet discussed above, and at- effect observed in other series.4J.22*23That the tributed to chromophores described by forms H, effect of the amino group is greater is consistent J and K. The triplet was not resolved in the spec- with its greater electromeric effect.lg I n those trum of X X . The other new band is a broad, low cases in which hydrogen bonding is p ~ s s i b l e ~ ~ ~ ~ ~ ~ ~ intensity absorptio9 extending into the visible the effect of hydroxyl is greater. Intramolecular region (4200-5000 A.). This low intensity band hydrogen bonding is not possible in XIV. One has been repo@ed for similar ketone^.^^,^ The might predict that the unknown a-hydroxy derivashoulder (3920 A.) in the spectrum of XV might be tive of I1 yould have a cinnamoyl band shifted considered to correspond to this band character- about 300 A. to longer wave length from the corresponding band of 11, and with little more than istic of a-substituted a,@-unsaturatedketones. The absorption maxima for the a-substituted one-half of the in tens it^.^!^^ One might also derivatives are lower than the corresponding expect a broad, low intensity band extending into maxima for the parent ketone 111, in the longer the visible r e g i ~ n . ~ ~ , ~ wave length region. However, inspection of the The spectral studies in the three series, I, I1 and spectral curves shows thatotheintegrated intensity I11 result in the following conclusions: in the region 2500-3000 A. is greater for the a1. The effects of substituents on a,P-unsubstituted ketones. Thus the longer, intensely saturated ketones vary widely not only with the absorbing chromophores of the parent ketone are nature of the substituent, but also with the posibroken into smaller chromophores (see H, J and K) tion nf the substituent in the molecule and the by the a-substituent. The resonance effect of the steric and electronic nature of the ketone system. substituents is seen a,s an increase in the absorption 2. I n the perinaphthenone-7 (111) system, exover the 2500-5000 A. range, and not in individual tensive resonance interaction is indicated both in bands. the ground state and excited state. Introduction of the hydroxy or morpholino 3. I n the cross-conjugated system (I),the subgroups into the @-positionof ketone I11 results in stituent effects are small. a hypsochromicoshift (110-280 PI.) of the bands in 4. I n the linear conjugated system (11), the the 3300-4000 A. region,. This may indicate that substituent effects are larger. the substituents contribute more resonance staInfrared Absorption Spectra Studies bilization to the ground state than to the excited state. The shift is greater for the hydroxyl Introduction.-The infrared absorption by kegroup. The @-substituents introduce no bands tones due to the carbonyl stretching vibration has which did not appear in 111,and some fine structure been intensively studied. Factors influencing the is lost.'O The inyease in intensity of absorption polarity of the carbonyl group, and thus the abin the 3300-4000 A. region may be attributed to the sorption frequency, have been discussed.24 Most extension of the resonating system and the greater of the studies of such factors have dealt with the electrical moment i n ~ o l v e d . ~ , ~ * immediate environment of the carbonyl group, The imino and epoxy derivatives have been dis- with some study of the farther-reaching resonance cussed elsewhere. The three membered ring effects. Conjugation effects of aryl and olefinic has a small effect on the resonance in this series groups in open chain compounds have been which is unlike the effect of either the a - or p(22) B. Eistert, F. Weygand a n d E. Csendes, BPY.,84, 703 (19.51). substituents. (23) T. M. Lowry, H. Moureu a n d C. A. H. MacConkey, J . C h e i i t . (21) H. S.Taylor a n d S . Glasstone, ' ' A Treatise on Physical Chemist r y , " Vol. I , 3rd e d . , John Wiley a n d Sons, Inc., New York, N. Y . , 1942, p. 281.
SOL,3171 (1928). (24) L. J. Bellamy, "The Infrared Spectra of Coulplea hlolecules," J o h n Wiley and Sons, Inc., New York, li.Y., 1954, Chapter $1.
3432
RICHARD D. CAMPBELL AND NORMAN H. CROMWELL
studied.24.25 Some substituent effects have been i n ~ e s t i g a t e d , ~but ~ . ~not ~ with endocyclic a,@unsaturated ketones. Hydrogen bonding effects have been observed.241z7 Such effects might operate in a-substituted endocyclic a$-unsaturated ketones but would be geometrically impossible in the P-derivatives. For some of the compounds involved in this study, infrared data have been determined using ljujol mulls. It has been pointed that intermolecular forces in condensed phases have an important influence on the infrared carbonyl absorption frequency. These forces can be minimized by using dilute solutions in carbon tetrachloride. The discussion above, concerning the ultraviolet spectra of these compounds, dealt with some evidence for the effect of the various substituents on the ground state of the endocyclic a#-unsaturated carbonyl system. It seemed of interest to obtain the more direct evidence of infrared spectra for these effects, and to study these spectra in relation to each other and to previous infrared data.24 Discussion of Results.-The physical state of the sample is important.24 In dilute carbon tetrachloride solution the carbonyl band generally was found to be 10-20 cm.-' toward higher wave nurnbers than the carbonyl band observed in the condensed phase (uiz.,liquid or Nujol mull). In some cases the difference was less, particularly in the perinaphthenone-7 (111) series. In the condensed phase, intermolecular effects might be expected to increase the polarity of the carbonyl group. Thus the solution data give a more reliable picture of the isolated molecule.25 I n the discussion which follows, references will be made almost exclusively to the solution data. The carbonyl absorption frequency gives evidence of the polarity (single bond character) of the carbonyl group. The norrnal undisturbed carbonyl frequency is 1705-1723 cm.-l in aliphatic ketones.24 Conjugation with an aryl group reduces the wave number to 1680-1700 cm.-l. Phenyl vinyl ketones and P-styryl ketones absorb in the same range25(yiz.,IBIS0 and 1690 cm.-', resp.). Endocyclic ketones I and IT absorb a t 1663 and 166% cxn-l, respectively. This indicates that resonance interaction causes the carbonyl groups to be slightly more polar than in the corresponding open chain compounds.z5 The cyclic conjugated systems in I and I1 are held rigidly in position for iiiasimurn resonance interaction and polarization.'s (2.j) S . Fuson, \I. L. Josien a n d E. I1 Shelton. THISJOIXXAL, 76, 2 j 2 8 (1934) (?ti) A . H. Snloway a n d S. I,. Friess, i b i d . . 73, 3000 (li7:l). [ 2 7 ) N. H . Cromwell, e i a i . , i h i d . , 71, 3337 (1949). ( 2 s ) I n this I>aboratory Pruf. H . E. Baumgarten hasrecenlly measured t h e infrared spectrum of highly purified benzalacetone. Using K u j o l mulls, b a n d s r e r e f o u n d a t , 108S(\'.S.,; lGti5(iY); l G l 5 - l f i O R (VS,),I585(S); G mg./ml. CClain 1.0 mm. matched cells, I699 ( i s % a b s . ) , 1078 ( 9 4 R abs ) ; 1017 (925% abs.). W e believe t h a t a C=O hanrl assignment should be made t o both t h e 1088-1699 a n d 166;N i 8 c m . - l b a n d s , T h e strong 1617-1802 c m . 3 b a n d s %reprobably composite C=C a n d conjugated phenyl bands. T h e t w o C=O bands are a p p a r e n t l y associated with two possible rotational isomers of t,,n,,s-benzalacetone; see footnote h , Table I, X. H. Cromwell and R. J . U o h r b a c h e r , THISJ U I : R S A L , 7 6 , G131 ( l 9 . 3 ) .
Yol.
'To
Perinaphthenone-7 (111) shows even more extensive resonance interaction between the carbonyl group and the rest of the aromatic system. The carbonyl absorption frequency (l(M cm.-l) indicates considerable polarity of the carbonyl group. Evidence for this extensive resonance interaction in the ground state of I11 and its derivatives was also noted in the ultraviolet spectra. The dihydro derivatives in the three series exhibit carbonyl bands in the range expecteci. Ketone V has an aliphatic carbonyl group, and absorbs a t 1712 an.-'. Ketones IV and VI1 are aryl ketones, and absorb a t 1685 and 1690 crn.-l, respectively. The a-bromine atom in VI shifts the absorption band 12 cm.-l to higher wave number, as expected.'? In all three series of unsaturated ketones, introduction of a bromine atom into the a-position caused a shift to higher wave numbers. This indicates that the strong inductive and coulombic field effects of bromine increase the double bond character of the carbonyl group. Several workersz4 have observed that the shift caused by an equatorial a-bromine mas 20 cm.-l in saturated ketones, where only the inductive and coulombic field effects can operate. In the 11, I and 111 series, the shift is progressively less (16, S. and -1- cni.-', respectively). This indicates that the resonance and electrostatic dipolar i n t e r a ~ t i o n ' ~of the bromine atom with the carbonyl group is progressively greater for the three series in the order named, and partly cancels the inductive and coulombic field effects, see Fig. 1. The resonance stabilization of the excited state for these coxnpounds has been discussed above, in relation to the ultraviolet spectra. ,yBri(?
C/\,
+-+-
(aBr8. G\oa
Fig. 1.-Coulombic field effect: equatorial bromine tentis t o suppress this indicated resonance in saturated cyclic kctones; see R. N. Jones, et a l . , THISJOURNAL, 74, 2830 (1952).
The effect of the P-morpholino or P-hydroxyl group on the carbonyl band of open chain a$unsaturated ketones is varied. ii'here hydrogen bonding (resonance chelation)24 is possible, the p-amino group?; reduced the carbonyl band wave number j ( t ( i 0 crn.-l. Even in the absence oi
c6i-r/
\Ii S-cis-t~,ans(labile) (C=O(cl, band, 1699 crn.-l)
C6H/ -\I1 S-tunns-t~nns(labile) (C=-Occlr band, 1078 ~
T h e endocyclic ket
