摘要:

1977 1983 Polarities and Hydrogen-bonding Abilities of the Aromatic Derivatives of Cyclohex-2-enone By Valery D. Orlov,' Yury N. Surov, Valentina N. Tischenko, and Vladimir F. Lavrushin, Department of Chemistry, Kharkov State University, Dzerzhinsky sq. 4, Kharkov 310077, U.S.S.R. The relative basicities of 3-aryl-5-phenylcyclohex-2-enones have been determined by i.r. spectroscopy from the shifts of the stretching frequency of the hydroxy-group of phenol hydrogen-bonded with these ketones and from the vcz0 values (in KBr, CCI,, and CHCI,) together with the dipole moments (in benzene). The values are dis- cussed and ccmpared with those of arylideneacetones having analogous conjugated systems. It is shown that the fixed s-trans-configuration of cyclohexenone derivatives causes their high polarities and basicities.Correlation analysis has been performed and it is found that the rigid x-system of cyclohexenone possesses a substantially better transmission of electronic influence in comparison with carbonyl compounds with an open-chain structure. ITis known that the conformation of +unsaturated The pellets used for the solid state measurements contained ketones determines the majority of their physico-1-2 mg of ketone per 100 mg of KBr. For the other chemical properties mainly because of its effect on the measurements a constant path-length (1mm) cell was used. mutual orientation of the polarities of the attached The temperature of the cell was regulated at 30.0 f0.5 "C. groups. For this reason, there is special interest in the Spectroscopic grade CCl, and CHCl, were dried over molecular sieves and stored in a dry box where all solutions investigation of the basicity and polarity of carbonyl were prepared.The ketone concentrations were GU. 0.01~compounds which, due to the fixed structure of the for the VC=O and 0.1~for the AVO-= studies and the starting propenone unit, do not have the conformational un-phenol concentration was 0.02~. The solutions containing certainty found with acyclic compounds. phenol and base typically yielded spectra in which the broad In the present study, the properties of 3-aryl-5-band due to the hydrogen bonded hydroxy-group did not phenylcyclohex-2-enones possessing fixed s-trans-overlap with the monomeric band for any of the compounds conjugated chains have been investigated.The shifts studied. The maxima for the hydrogen-bonded hydroxy TABLE1 Experimental data I ----CH,-l p-K'C6H4'C:CH.C0.CH,.CH.C6H4R2-P rlcHrlai AvOH/ vc=o/cm-l P/D p-RIC,H,CH:CHCOMe P-R1C,H4CH:CCOCH, K1 RZ No. M.p. ("C) cm-' KBr CC1, CHC1, obs. calc. Pb II V/D II H H (I) 89-90 * 247 f 1 1663 1673 1659 3.579 3.60 3.31 3.14 CH, H (11) 106.5-251 f 1 1661 1673 1658 4.00 3.82 3.63 (V) 107.5 t OCH, H 107-108: 255 f1 1658 1671 1656 4.21 4.01 3.19 N(CH,), H 167 285 f2 1650 1660 1644 5.54 4.53 5.30 c1 H 98-99s 239 & 2 1662 1675 1662 3.159 3.12 2.63 2.75 Br H (VI) 117 236% 2 1661 1676 1662 3.22 3.13 2.89 NO, H (VII) 130 203 f1 1667 1685 1672 3.68 3.82 3.45 OCH, OCH, (VIII) 110-111 261 f3 1656 1669 1654 (IX) 7 64 253 f2 1661 1673 1658 3.64 3.60 * Literature values of the m.p.vary between 80 and 90 OC. The value 89-90 "C has been reported by D. Nasipuri, S. R. R. Chouldhury, and A. Bhattacharya, J.C.S. Perkin I, 1973, 1451 ; H. E. Zimmerman, D. F. Juars, J. M. McCall, and B. Schroder, J. Amer. Chem. SOC.,1971, 93, 3662. t Lit. m.p. 103-104 "C (A. D. Petrov, and L. I. Antzus, Ber., 1933, 66B,420). Lit. m.p.103-104 "C [R. G. Grict, G.P. 1,921,348 (Chem.Ah., 1970, 72, P54,991d)]. 9 Lit. m.p. 95 "C, kba. 3.4 D for (V); Pobo. 3.9 D for (I) lit. m.p. 64 "C (S. M. Abdullah,(A. Y. Meyer and E. D. Bergmann, Israel J. Chem., 1968, 6, 735). 7 3-Yhenylcyclohex-2-enone,J. Indian Chem. Soc.,[1935,12,!62). 11 The values of p were taken from 0.A.Osipov, V. I. Minkin, and A. D. Garnovskiy, ' Handbook of Dipole Moments,' Vysshaya shkola, Moscow, 1971, 3rd edn. of the stretching frequency of the hydroxy-group of stretching bands were determined by a triangulation phenol (AVO-=) in ketone-phenol-CC1, systems, the procedure. The intersection of the lines that best fit the characteristic stretching frequency of the carbonyl group sides of the band was taken to be the centre of the peak. Dipole moments (pobs)were measured by the Hedestrand (vG0) in the solid state (KBr pellets) and in CCl, and CHC1, solutions, and the dipole moments (p) of these procedure in benzene at 25 "C. For pcalc.the standard group moment values6 were used, except that po=o wascompounds were measured. Analogous data have been taken as equal to p for cyclohex-2-enone (3.6 D ').Eachreported 394 for a group of labile s-trans-conformers of VC=~ and pobs. entry is the average of at least two separate arylideneacetones of similar conjugation. L. P. Pivovarevich, L. A. Kutulya, Yu. N. Surov, L. M. EXPERIMENTAL Satanovski, and S. V. Tsukerman, Reakts. spos. org. Soedinenii,M.p.s and physical data for the compounds studied are 1973, 10, 119. given in Table 1. L. A. Kutulya, L. P. Pivovarevich, Yu. N. Surov, L. M. 1.r. spectra were recorded with a UR-20 spectrometer. Satanovski, and S. V. Tsukerman, J. Org. Chem. (U.S.S.R.),1975,11, 2094. R. Mecke and K. Noack, Spectrochim. Acta, 1958, 12,391; G. Hedestrand. 2.phys. Chem., 1929, B2,428. Chem. Ber., 1960, 93, 210; F.H. Cottee, B. P. Straughan, C. J. V. I. Minkin, 0. A. Osipov, and Yu. A. Zhdanov, ' DipoleTimmons, V. F. Forbes, and R. Shilton, J. Chem. SOC.(B),1967, Moments in Organic Chemistry,' Khimiya, Leningrad, 1968,p. 79. 1146. D. J. Rertelli and T. G. Andrews, Tetrahedron Letters, 1967, R. L. Erskine and E. S. Waight, J.Chem. Soc., 1960,3425. 4467. determinations. The Av0-H values were calculated statis- tically from 7-8 independent measurements. DISCUSSION The electric dipole moment of an organic compound is one of the most direct measures of the total polarization of the ground state of the molecule. For that reason, it is interesting to use that quantity for analysis of the cyclohex-2-enone derivatives. The values of pobs.for cyclohex-2-enone (3.62 D 7), 3-phenyl-(3.64 D), and 3,5-diphenyl-cyclohex-2-enone (3.57 D) are very close.Apparently, the effect of the aryl group on the total polarization of the molecule is very small. On the other hand, p for the cyclohexenone ring is larger than expected based on an enone model. Since the directions of the carbonyl group and the adjacent double bond polarizations are parallel, the cal- culated moment should be the sum of pc=o (2.7 D) and pso (0.4 D 6), i.e., pcalc.3.1 D. The difference between p&s. and pcLcalc.is large enough (ca. 0.5 D) to indicate that there is interaction between these groups. In our cal- culation of p for compounds (1)-(VII) a correction for J.C.S. Perkin I1 ations. The vG0 values in different media are shown in Table 1.It is known 8 that in going from CCl, solution to the solid dispersion in KBr the value of vc=0 decreases because of a change in the dipole-dipole interaction. A stronger interaction increases Avc=o. In the present case, the large AvGo values are due to the high polarity of the carbonyl group as confirmed by the p values. Because of that high carbonyl group polarity the difference between vG0 in CC1, and CHC1, is also large (13-16 cm-l). The changes in veo due to the electronic influence of the R1substituents (see Table 1) are greater than the error of the method and reflect the different carbonyl group polarities that result. Despite the long distance (three single bonds) over which it acts the influence of the aromatic ring upon the carbonyl group is observable. The negative inductive effect of the phenyl group is shown by comparing the values of v~=~,and especially, Av0-H for compounds (I) and (IX) and the donor effect of the 9-methoxyphenyl group is similarly seen by com- parison of the values for (111)and (VIII).The AvwH values are the most sensitive indications of TABLE2 Data for correlation analysis Set No. Equation b8-H = ilv8-H + mo AVE-~= Av8-H + mo+ a (3) Avos = A,,:-= + mooo + mRoR+ .IV:-~= Av& + WZ~F+ mrR v&~= vgz0 -k mo v:=~ = vgz0 + ma+ = ~$ + mooO + mRbRf2~ = + mfF + m,R mf m = -48.8 (-44.4) m = -29.5 (-30.9) mo = -45.1 (-39.7) !mR = -13.2 (-8.9)mf = -27.9 (-25.0) m, = -48.5 (-44.3) m = 14.6 mf = 7.0 (5.0) {mr = 13.3 (10.2) * Data in parentheses are for corresponding s-trans-arylideneacetones.t Standard deviation. so f Y *,$ 4.9 0.99 (0.98) 7.6 0.96 (0.94) 38 0 99 (0.96) 4.7 0.98 (0.94) 1.5 0.98 1.9 0.97 1.7 0.98 (0.97) 1.6 0.97 (0.95) $ Correlation coefficient. this interaction has been made and the p,lc. values ob-tained are in good agreement with p&s. (see Table 1). An exception is ketone (IV) in which the strongly elec- tron-donating dimethylamino-group exerts much influence on the carbonyl group, creating an additional interaction moment. The values of pobs. presented in Table 1 show that the polarizations of cyclohexenone derivatives are consider- ably greater than those of the n-analogue derivatives of benzylideneacetone and 2-benzylidenecyclohexanone. The arylideneacetones exist as s-trans-and s-cis-rotamer mixtures 2-4 while 2-arylidenecyclohexanones have only the s-cis-form. It may be concluded that the con-formation is the principal factor causing the difference in p for related compounds in those series.The conform- ation also determines the polarity of the carbonyl group for each rotamer. We now turn to the polarities of some compounds which have the same conformation. 1.r. spectral measurements are especially helpful for such investig- L. J. Bellamy, ‘ The Infrared Spectra of Complex Molecules,’ Wiley, New York, 1958, p. 379.* D. Pitea and G. Favini, J.C.S.Perkin II, 1972, 142. the carbonyl polarity.The formation of the hydrogen- bonded complex causes a small displacement of the ketone from its ground state. Comparison of our values of Avo--H with those found for a series of arylideneacetone s-trans-rotamers shows that the latter are smaller. The carbon skeleton of a cyclic molecule is more rigid than that of an open-chain ali- phatic conjugative bond system, e.g.,benzylideneacetone which exists as a mixture of conformers. Briegleb-Stuart models show that the conjugative bond system of the cyclohexenone derivatives (1)-(VII) is almost planar, a conclusion reached earlier by 0the1-s.~~~ This is surely the dominant factor causing the high polarity of the unsaturated cyclic ketones of s-trans-configuration. The transmission of electronic influence is a matter of interest here.As we have pointed out in our pre-liminary communications,1° rigidity of the conjugative chain simplifies the consideration of electronic interac- tion because it removes conformational uncertainty. 10 V. D. Orlov, I. A. Borovoy, Yu. N. Surov, and V. F. Lav-rushin, J. Gen. Chem. (U.S.S.R.),1976,46,2138; N. S. Pivnenko, V. D. Orlov, I. A. Borovoy, and V. F. Lavrushin, J.Org. Chem. (U.S.S.R.),1974, 10, 1236. We have been able to make a quantitative estimate of the influence of substituents in the 3-phenyl ring upon the VGO and AVO-= values by carrying out a comprehensive correlation analysis employing both the monoparameter equations of Hammett (1) l1 and Brown (2) l1 and the two-parameters equations of Yukawa-Tsuno (3) l1 and Swain-Lupton (4).12 The results of the analysis are given in Table 2.The data in parentheses were obtained earlier 394 for a series of analogous s-trans-arylidene- acetones. It is important to note that, as shown by the r values, vc=o and Avo-= correlate well with all the para- meters and that the correlations are better than those shown by the arylideneacetones. A second important result is the demonstration that the sensitivity of the shifts and of the carbonyl frequencies to the electronic influence of a substituent, as shown by the m para-meters, is also greater for the compounds investigated here. In other words, these compounds have greater electron transmission along their conjugative chains.This is due to the rigidity of the molecules and to the high planarity of the conjugative portion of the cyclo- hexenone derivatives. The superior correlations with all parameters also mean that an inductive as well as a conjugative factor is taking part in the electronic interaction in the molecule. l1 I. A. Zhdanov and V. I. Minkin, ' Comparative Analysis in Organic Chemistry,' Rostov University, Rostov-on-Don, 1966. For the series of arylideneacet~nes,~~~The Yukawa- Tsuno equation is preferable for two-parameter cor-relations. For both veo and Avo-=, the high sensitivity to inductive influence is observed using this equation. This was surprising because of the distance of attachment of the 3-aryl groups. In the two sets (a and b) in Table 2, we note that the m values are higher in the first, the differences being appreciably greater than the experimental error. This confirms the statement made above about the greater sensitivity of the AVO-= values to electronic interaction in the molecule. Finally, attention is called to an interesting experi- mental fact. In the i.r. spectra of a majority of the ketones studied in CC1, solution, a peak of low intensity or a shoulder on the high-frequency side of the carbonyl band has been detected. This phenomenon may be due to Fermi resonance splitting. The splitting disappears if the medium is changed, for example, from CCl, to CHCl,. The same observation has been made previously for other cyclic ketones1, We thank Dr. J. C. Miller for his advice and interest. [7/361 Received, 1st March, 19771 l2 C. C. Svain and E. S. Lupton, J.Amer. Chem. Soc., 1968, 90, 4328. l3 I(.Noack, Sflectrochim. Acla, 1962, 18, 697.

ISSN:1472-779X    

DOI:10.1039/P29770001983

出版商:RSC    

年代:1977

数据来源: RSC