Infrared Spectra of Cinerolone and Synthetic trans-(2-Butenyl~-4-hydroxy-3-methyl2-cyclopenten-1-one RY IT.
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The chrysanthemum acid esters of pyrethrolonr constant value of 1" throughout the spectrum. The pertransmission of the sample was determined on a and cinerolone constitute the principal itisecticitlal centage point-to-point ba4s by dividing the intensity of radiation constituents of pyrethrum flowers. Wheri cineml- passing through the sample cell by the corresponding inone is reesterified with d-trans-cfirysaritheinuin tenrity pasiing through the blank cell. monocarboxylic acid, the resulting cinerin T has Discussion of Results been shown to be of about the same order oi t o x i c The infrared spectra for wave lengths from 2 to ity as pyrethrin I, with the added advantage oi greater stability.2a Recently Schechter, Green, 15 microns are presented in Fig. 1. From 2 miand LaForge3 have described the synthesis of a crons to about 7.5 microns, in the higher freseries of cyclopentenolones closely related to cin- quency range where the bands are due exclusively erolone, which, when esterified with synthetic or to interatomic bonds, the two spectra are subnatural chrysanthemum monocarboxylic acids, stantially the same. A t higher wave lengths, yield esters having a high order of insecticid,'1 1 ac- where the absorptions are due in part to vibrations tivity, with knockdown and paralytic effects o f the molecule as a whole, the spectra differ to a considerable degree. The most pronounced difcharacteristic of pyrethrum extracts. Schechter, Green and LaForge3 thought it prob- ierence is a t 10.36 microns, where the synthetic able that their synthetic 2-(%butenyl)--l.-hydroxy- illaterial alone has strong absorption. The nat3-methyl-2-cyclopenten-I-one and natural cinerol- ural material alone has an absorption band in the one were cis-trans isoniers, the synthetic com- 14.0-14.ci micron region. The higher frequency pound being the truns lorm. Similar conclusions hands have been correlated with the normal frewere reached by Harper4 in the case of c i n e r ~ n e . ~quency ranges within which certain atomic groupThe cis-trans isomerism concerns the double bond ings have been found to absorb, largely on the in the butenyl side chain. 'The writer has found basis of the work of Barnes, Gore, Stafford and that the infrared absorption spectra of the two Williams.' The C=O band falls within the compounds are of value in differentiating them range assigned to a,P-unsaturated ketones (Cromwell, et U Z . , ~ ) . The correlations, presented in Taand in confirming their molecular structiiri.. ' ble I, confirm important structural features of the Experimental niolecule. In this table are included the lower infrared spectra were obtained on a single-beam 1~riwi frequency bands attributed to the cis and trans spectrometer equipped with J. sodium chloride prism .tnd germetric:il structures, as ctiscucsed below.
sodium chloride windows a n d rells. Thermocouple 0111put amplication is through a d . c. breaker-type amplifier, with zero adjustment a t the amplifier. Blank and w u p l e energy records were made consecutively, over limited spectral regions, on an electronic stripchart recorder. Within the ranges where solutions were used c 1 lnctors were applied to correct for differences in cell tril,srnission by the solvent and solution cells. The effects of stray radiation were minimized by using shutters of LiF (15 to 9.9 microns), glass (9.9 to 8.4 microns), and opaque material (5.4 to 2.0 microns), Slit widths were changed stepwise, with actual slits of 1.070 rnm. at 15 microns and 0.032 mm. at 2 microns. An automatically driven variable resistance (attenuator\ ic'rverl to 111 aintain a fairlv
L\ i . r c length LII
inicrottc Synthetic Frequenc) Irniis'cm -11
Cinerolone
2.91
2 91
3.30 3.42
:i3 0
:i12
ltiBS
1650
11) Article not copyrigiitw
12) W' A Gersdorff, .i r I 40 874 LQ47) h) 48, 532 (1949) 3) Milton S Schechter, Nathan Lretri i i i d I h I i i orir 1 H I > JOURNAL, 11, 3165 (1949) 14) Stanley K Harper, J Chcm S O L892-895 , (1Ylb) (6) Since the spectra presented in thi5 paper were ohtain.4, the synthesis of (*)-crs-cinerolone has been announred 1, Cromhie mid 5 H Harper, N a t u r e , 164,551 (1949) (6) The author express- hi& appreciation t o M S Schechter N Green and F. B. LaForge for the samples used in this work, and for their respective physical constants Synthetic 2-(2-butenyl)-4hydroxy-3-methy1-2-cyclopenten 1-one b p 113-11 5" a t 0 25 mrn , n * b 1.5132. Natural cinerolone. 1) p 118-lZ0° at 0 2 mm , u p i n 1,5221. Although the natural cinerolone may not haxe been perfectly pure. the infrared spectrum shows no evidence of impurit\ Both samples were regent.r?trd from t h e remrcarbazonr\
3436 303l 2924
1137 l3,sR
!I65 700
bnnctional g r o u p
OH (bonded) Unsatd. C-H (aliphatic) Satd. CH,; satd. C-H: 5atd. CH2 (unresolved bands] C.0 C:C
Satd. CII C-CH? t r a m RCH=CHR' C I S RCH-CHR'
liasmussen, Brattain and Zuccoe have pointed out that the 10.3-micron band is characteristic of the trunr form of the group RCH=CHR', rather (7) R Bowling Barnes, R C Gore, R W Stafford and V L lbilliams z b t d , 20, 402-410 (1948) (8) N H Crornwill, F A Miller, A K Johnaon, R T Frank aud
n
J
xdtiace
(0) R i'h\
TXIS j c l r K \ ~ L , 71, 3~ 3322 (1949) b Rawnubsen, R R Fir I t t s l n and P Zucco I ( l r v
1 5 1'35-140 (1c)47
INFRARED SPECTRA OF CINEROLONE
Oct., 1950
IC 0
:O 5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
4523
14.5
15,:
W o v e Length in Microns
.
Fig. 1.
than of both cis and trans forms, as had been previously assumed. Kilpatrick and Pitzer,lo in a vibrational analysis which included consideration of infrared and Raman data of other workers, assigned the 10.37-micron infrared band of trans-2 butene to a wagging vibration of the two hydrogen atoms out of the plane of the carbon skeleton. Anderson and Seyfried" empirically assigned normal band positions for various functional groups in oxygenated and olefin-type compounds as found in synthesis-type naphthas. They include a trans RCH=CHR' band a t 10.36 * 0.02 microns and a cis band a t 14.0-14.6 microns. Fred and Putscher,'* from a study of the source of the 10.3-micron band, which occurs in Pennsylvania lubricating oils, conclude that olefins with internal, unsubstituted, trans double bonds are the only class of hydrocarbons with a characteristic 10.3micron band, although they point out that other compounds, including the alkyl cyclohexanes, may absorb in this region. They also state that trans olefins are apparently more abundant in nature (10) John E. Kilpatrick and Kenneth S. Pitzer, J . Kereorch Nut. Bur. Sfundords, 38, 191-209 (1947). (11) J. A. Anderson, Jr., and W. D. Seyfried, A h . Chcm., 80,908-
1006 (1948). (12) Mark Fred and Richard Putscher, Anal. Chcm., 81, 900-911 (1949)
than cis olefins, in accordance with their greater stability. It may therefore be concluded that the infrared spectra presented in this paper show with reasonable certainty that the two compounds,are cistrans isomers, and that natural cinerolone is the cis form and the synthetic 2-(2-butenyl)-4-hydroxy-3-methyl-2-cyclopenten-1-one the trans form. This confirms the conclusions of Harper4 and of Schechter, Green and LaForge.s In this case, therefore, i t is found that the naturally occurring material is the cis form, which appears to be the less stable form. Summary Infrared spectra of natural cinerolone and synthetic 2-(2-butenyl)-4-hydroxy-3-methyl-2-cyclopenten- 1-one have been obtained over the wavelength range of 2 to 15 microns. The spectra indicate that the compounds are cis-trans isomers, and that the naturally occurring compound is the cis form and the synthetic compound the trans form. The spectra confirm the molecular structures as determined by Harper and by LaForge and co-workers. BELTSVILLE, MD
RECEIVED APRIL6, 1950
