Zora Šusteková

Infrared spectra and theoretical study of methyl, formyl and acetyl derivatives of chromones

SummaryThe C=O stretching frequencies of substituted 2-methylchromones (3a–3j), 2-formylchromones (4a–4j), 3-formylchromones (5a–5j) and 3-acetyl-2-methylchromones (6a–6i) were measured in CCl4 and CHCl3 and correlated with σ+ substituent constants. Using the results of the infrared spectral investigation and the theoretical calculations by the semiempirical AM1 method, the conformation and the transmission of electronic effects in compounds4–6 were studied. For the 2-substituted chromone system the transmission factory γ according to the definition of Charton was determined. The preparation of some new 2-methylchromones (3e–3j) and 3-(2,2-diformyl-chlorovinyl)-6-methylchromone (7) is also described.ZusammenfassungEs wurden die C=O-Streckschwingungsfrequenzen von substituierten 2-Methyl-chromonen (3a–3j), 2-Formylchromonen (4a–4j), 3-Formyl-chromonen (5a–5j) und 3-Acetyl-2-methylchromonen (6a–6j) in CCl4 und CHCl3 gemessen und mit den σ+-Substituenteknonstanten korreliert. Unter Verwendung der IR-Resultate und theoretischer Behandlung mit Hilfe semiempirischer AM1-Rechnungen wurden die Konformationen und die Transmission elektronischer Effekte in den untersuchten Verbindungen4–6 untersucht. Für die 2-substituierten Chromon-Systeme wurde der Transmissionsfaktor γ entsprechend der Definition von Charton bestimmt. Die Herstellung einiger neuer 2-Methylchromone (3e–3j) und 3(2,2-Diformyl-1-chlorvinyl)-6 methylchromon (7) wird ebenfalls beschrieben.

Dual Substituent Parameter Modeling of Theoretical, NMR and IR Spectral Data of 5-Substituted Indole-2,3-diones

Correlations of AM1 and PM3 theoretical data, 13C-NMR substituent chemical shifts (13C-SCS) and IR carbonyl group wave numbers [ν(C3═O)] were studied using dual substituent parameter (DSP) models for 5-substituted indole-2,3-diones. For the C7 atom a reverse substituent effect attributed to extended π-polarization was observed. On the other hand, the DSP approaches for the C3 atom showed normal substituent effects with some contribution of reverse effect supported strongly by 13C-SCS correlations. In the ν(C3═O) and p(C3═O) DSP correlations the field effect contribution predominates over the resonance effect, which justifies the using of earlier suggested vibrational coupling (V-C) model for 5- and 6-substituted indole-2,3-diones.

Structure-Reactivity-Spectra Correlations for Substituted 3,4-Diphenylcyclobut-3-ene-1,2-diones

Summary. The infrared absorption bands of the C*O stretching vibration and the 13C NMR chemical shifts were measured for a series of nine substituted 3,4-diphenyl-cyclobut-3-ene-1,2-di-ones in CHCl3, CDCl3, and partially in CCl4. The AM1 charge densities, bond orders, and valence angles were calculated for the optimized geometry. Good to satisfactory mutual correlations were found between the arithmetic means of the wave numbers of symmetric and asymmetric C*O stretching vibrations, Hammettσ constants, rate coefficients, and enthalpies of activation of the base-catalyzed ring fission as well as the AM1 oxygen charge densities and bond orders at the carbonyl groups. The results show that the factors controlling the reactivity of these compounds and the structural and IR spectroscopic properties of the C*O groups must be the same. The correlation between the wave numbers of symmetric and asymmetric C*O stretching vibrations affords a slope of a=1.069 which points to the existence of a strong cross-conjugation effect in the cyclobutenedione ring. The correlation of the wave number separation of the absorption bands of symmetric and asymmetric C*O stretching vibrations (Δv(C*O)) for various cyclic diketones enabled the prediction of the angle γ=83° between the bond vectors of the two carbonyl groups in the cyclobutenedione rings, which is in satisfactory agreement with the value calculated by the semiempirical AM1 method.Zusammenfassung. Die Infrarotabsorptionsbanden der C*O Streckschwingung und die chemischen Verschiebungen der 13C NMR Signale wurden für eine Reihe von neun substituierten 3,4-Diphenylcyclobut-3-en-1,2-dionen in CHCl3, CDCl3 und teilweise in CCl4 gemessen. Die AM1-Ladungsdichten, Bindungsordnungen und Bindungswinkel wurden für die Optimalgeometrie berechnet. Zwischen den arithmetischen Mitteln der symmetrischen und asymmetrischen C*O-Streckschwingung, den Hammettschen σ-Konstanten, den Geschwindigkeitskoeffizienten und Aktivierungsenthalpien der basenkatalysierten Ringspaltung sowie den AM1-Sauerstoffladungsdichten und Bindungsordnungen der Carbonylgruppen wurden gute bis befriedigende Korrelationen gefunden. Die Resultate zeigen, daß die Faktoren, die die Reaktivität dieser Verbindungen kontrollieren, dieselben sind wie jene, die die strukturellen und IR-spektroskopischen Eigenschaften bedingen. Die Korrelation zwischen den Wellenzahlen der symmetrischen und der asymmetrischen C*O-Streckschwingung hat einen Anstieg von a=1.069, was auf einen starken Kreuzkonjugationseffekt im Cyclobutendionring hinweist. Die Korrelation der Wellenzahlenseparation der symmetrischen und asymmetrischen C*O Streckschwingungen (Δv(C*O)) für verschiedene zyklische Diketone läßt einen Winkel von γ=83° zwischen den Bindungsvektoren der beiden Carbonylgruppen des Cyclobutendionringes erwarten, der ausgezeichnet mit dem durch die semiempirische AM1-Rechnung erhaltenen übereinstimmt.

Fermi Resonance in Substituted Z-3-Methylene Phthalides

SummaryThe absorption bands of the C=O Stretching vibrations of a series of thirty-nine substitutedZ-3-methylene phthalides (1a-s, 2a-h, 3a-f, 4a-c, and5a-c) were measured in CHCl3 and CCl4. The two-levelFermi resonance effect on the infrared spectra of the above compounds was investigated after deconvolution and band separation. The wave numbers of the unperturbed fundamental C=O stretching vibrations exhibit excellent linear correlations withHammets constants of substituents and13C NMR chemical shifts of the C=O group.ZusammenfassungDie Absorptionsbanden der C=O-Streckschwingung von 39 substituiertenZ-3-Methylenphthaliden (1a-s, 2a-h, 3a-f, 4a-c und5a-c) wurden in CHCl3 und CCl4 vermessen. Durch Dekonvolution und Bandentrennung konnte der EinflußFermi-Resonanz auf die Infrarotspektren der obengenannten Verbindungen untersucht werden. Die Wellenzahlen der ungestörten C=O-Streckschwingungen ergeben ausgezeichnete lineare Korrelationen mit denHammetschen Substituentenkonstanten und den13C-NMR-Verschiebungen der Carbonylgruppe.

Spectral properties and kinetics of the alkaline hydrolysis of chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones]

Abstract The infrared and 13 C NMR spectra and the kinetics of alkaline hydrolysis of chromium, tricarbonyl[3-[( η 6 -aryl)methylene]- Z -1(3H)-isobenzofuranones] have been studied in comparison with those of 3-arylmethylene- Z -1(3H)-isobenzofuranones. The 13 C NMR spectroscopy has been found to be the most suitable tool for recognition of the site of complexation in the 3-arylmethylene- Z -1(3H)-isobenzofuranone system. A statistically significant correlation has been found between the arithmetic means of the wave numbers of symmetric and asymmetric stretching vibrations of Cr(CO) 3 group and σ p constants of the substituents. The large slope of this linear dependence suggests an important role of the mesomeric mechanism in the transmission of electronic effects to the Cr(CO) 3 moiety. The strong electron-withdrawing effect of the Cr(CO) 3 group causes a significant decrease of the polarity of the phthalide CO bond. The reaction rates of the alkaline hydrolytic ring-opening reaction dramatically increase due to the effect of Cr(CO) 3 group. The absorption bands of the carbonyl stretching vibrations are markedly split due to Fermi resonance effect. After mathematical correction for Fermi resonance the wave numbers of the unperturbed fundamental CO stretching vibration and the log k values of alkaline hydrolysis exhibit significant linear correlations mutually, as well as with Hammett σ substituent constants. Chartons transmissive factors γ (PhCr(CO) 3 ) have been determined for tricarbonylchromiumphenyl system using the parameters of the linear correlations. The efficiency of the substituent effect transmission is high in CCl 4 , because a back-donation effect of the carbonyl ligands and decreases in CHCl 3 due to the hydrogen bonding between carbonyl groups and solvent molecules. The preparation of some novel chromium, tricarbonyl[3-[( η 6 -aryl)methylene]- Z -1(3H)- isobenzofuranones] is described.

Structure-Reactivity-Spectra Correlations for Substituted Benzenesulfonamides

The infrared absorption bands of the S=O and N-H stretching vibrations as well as the natural abundance 13 C and the 17 O NMR chemical shifts were measured for fifteen substituted benzenesulfonamides in CDCl 3 and acetone-d 6 . For the unsubstituted compound the natural abundance 33 S NMR chemical shift was also measured in acetone-d 6 PM3 charge densities and bond orders were calculated for the completely optimised geometry. Mutual correlations are reported between the wave numbers of the asymmetric SO 2 stretching vibration, the arithmetic means of symmetric and asymmetric NH 2 stretching vibrations, Hammett or + substituent constants, dissociation constants, 1 H, 13 C, 15 N and 17 O NMR chemical shifts as well as the PM3 S=O and N-H bond orders and hydrogen, nitrogen and oxygen atom charge densities. The results of the correlation analysis showed that the factors determining the electronic structure and controlling the dissociation equilibria, the IR and NMR spectral properties of substituted benzenesulfonamides must be the same.

Structure-Acidity-IR Spectra Correlations for p-Substituted N-Phenylsulfonylbenzamides †

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same.

Cyclokondensationen von O-ethyl-S-Substituierten Dithiocarbonaten zu neuen 4-Alkylthio-1,3-Dithiol-2-Thionen mit Hilfe von Schwefelkohlenstoff

Abstract 4-Alkylthio-5-(p-nitro-phenyl)-1,3-dithiole-2-thiones 4a-e, 4-alkylthio-5-(p-, bzw. o-cyano-phenyl)-1,3-dithiole-2-thiones 4f, 4g, 4-alkylthio-5-pivaloyl-1,3-dithiole-2-thiones 4h-j und 5-methylthio-2-thioxo-1,3-dithiole-4-carboxylic acid N-methyl-p-chlor-bzw,-p-methoxy-anilides 4k, 41 are obtained by reaction of the O-ethyl-S-substituted dithiocarbonates 3 with carbon disulfide/potassium tert. butoxyde in dry DMF and alkylation reagent. Treatment of 1,3-dithiole-2-thiones 4a-c with mercuric acetate give 1,3-dithiole-2-ones 5a-c. Carbonyl stretching frequencies of 2-oxo-substituted five-membered heterocycles I are discussed.

A correlative IR, MS, 1H, 13C and 15N NMR and theoretical study of 4-arylthiazol-2(3H)-ones

Sixteen 4-arylthiazol-2(3H)-ones (3) were synthesised by cyclisation of α-thiocyanatoacetophenones (1) in acid solution. They appear to prefer greatly the oxo tautomeric forms. In CCl4 solution an equilibrium between the free CO bond and a “dimeric” hydrogen-bonded form exists in which the latter predominates. Several IR and NMR (1H, 13C and 15N) spectral properties are shown to correlate with Hammett σ-values and/or atomic Mulliken charges and bond orders, the latter being estimated by PM3 or AM1 semiempirical methods. The electron-impact mass spectra were also recorded and the fragmentation mechanisms interpreted in terms of the energetics of the ionic species. In addition, the geometric and electronic properties of 4-phenylthiazol-2(3H)-one (3a) and the related benzothiazol-2(3H)-one (4) based on ab initio HF/6-31 G* calculations are compared with each other.

Infrared spectra and theoretical study of the conformations of substituted benzoylketene-S,S-acetals

SummaryThe C=O stretching frequencies of substituted benzoylketene-S,S-dimethylacetals (1a–1o) and benzoylketene-S,S-ethyleneacetals (2a–2m) were measured in CHCl3 and CCl4 and correlated with theHammett substituent constants. The correlations were split into two different and well separated lines for compounds containing electron donor and electron acceptor substituents, which were assigned tos-trans ands-cis quasiplanar conformations. The correlations of carbonyl stretching frequencies with C=O bond orders and oxygen atom charge densities calculated using the semiempirical AM1 method reveal similar results consistent with assignments of structures1 and2 to two quasiplanar conformations. The preparation of some new benzoylketene-S,S-acetals is reported as well.ZusammenfassungDie C=O-Streckfrequenzen substituierter Benzoylketen-S,S-dimethylacetale (1a–1o) und Benzoylketen-S,S-ethylenacetale (2a–2m) wurden in CHCl3 und CCl4 gemessen und mit denHammet-Konstanten in Beziehung gesetzt. Es ergaben sich zwei deutlich unterschiedliche Gerade für Verbindungen mit Elektronenakzeptoren und mit Elektronendonatoren als Substituenten, die dens-trans- unds-cis-quasiplanaren Konformationen zugeordnet wurden. Die mittels der semiempirischen AM1 — Methode berechneten Korrelationen zwischen C=O-Streckfrequenzen und C=O-Bindungsordnungen bzw. Ladungsdichten am Sauerstoffatom ergeben ebenfalls eine Zuordnung der Verbindungen1 und2 zu zwei quasiplanaren Konformationen. Die Herstellung einiger neuer Benzoylketen-S,S-acetale wird ebenfalls beschrieben.