Alexander Perjéssy

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.

Infrared study of solvent-solute interactions of 1-substituted 2-pyrrolidinones and related compounds

SummaryThe wavenumbers of the carbonyl stretching vibrations of 2-pyrrolidinone (P), 1-methyl-2-pyrrolidinone (MP), 1-isopropyl-2-pyrrolidinone (IPP), 1-(2-hydroxyethyl)-2-pyrrolidinone (HEP), 2-oxobenzothiazole (OBT), and 3-octyl-2-oxobenzothiazole (OOBT) were measured inn-hexane/CDCl3, acetonitrile/D2O, methanol/D2O, and 2-butoxyethanol/D2O mixtures and compared with similar data for 1-cyclohexyl-2-pyrrolidinone (CHP) and dimethylacetamide (DMA). The dependencies of the wavenumbers on the mole fraction of the less polar cosolvent in binary mixtures allow a distinction and assignment of all species resulting from weak solute-solvent and solute-solute interactions. The slopes of the dependencies of the wavenumbers on the mole fraction for similar intermolecular species inn-hexane/CDCl3 mixtures correlate well with the relative hydrogen bond basicities (i.e. hydrogen bonding abilities with phenol) and reveal that the solvent sensitivities significantly depend on the steric requirements in the vicinity of the C=O group. On the other hand, the slopes of similar dependencies in acetonitrile/D2O mixtures are proportional to the electron donating effects of alkyl groups attached to the nitrogen atom of the pyrrolidinone ring. In the case of mixtures formed by two strongly hydrogen bonding cosolvents (alcohols/D2O), a competitive equilibrium occurs between the hydrogen bonding tendency of both cosolvents and 1-substituted 2-pyrrolidinones. In solutions of 1-substituted 2-pyrrolidinones in water-rich 2-butoxyethanol/D2O mixtures, microheterogeneous domains occur before classic mixtures of two polar liquids are formed.ZusammenfassungDie Wellenzahlen der Carbonylstreckschwingungen von 2-Pyrrolidinon (P), 1-Methyl-2-pyrrolidinon (MP), 1-Isopropyl-2-pyrrolidinon (IPP), 1-(2-Hydroxyethyl)-2-pyrrolidinon (HEP), 2-Oxobenzothiazol (OBT) und 3-Octyl-2-oxobenzothiazol (OOBT) wurden inn-Hexan/CDCl3, Acetonitril/D2O, methanol/D2O und 2-Butoxyethanol/D2O gemessen und mit den entsprechenden Daten für 1-Cyclohexyl-2-pyrrolidinon (CHP) und Dimethylacetamid (DMA) verglichen. Die Abhängigkeit der Wellenzahlen vom Molenbruch des weniger polaren Lösungsmittels in binären Mischungen erlaubt eine Unterscheidung und Zuordnung aller durch schwache Wechselwirkungen zwischen gelöster Substanz und Lösungsmittel bzw. durch Wechselwirkungen der gelösten Moleküle untereinander entstehenden Spezies. Für ähnliche Moleküle inn-Hexan/CDCl3 — Mischungen korrelieren die Steigungen der Abhängigkeiten der Wellenzahlen vom Molenbruch gut mit den relativen Basizitäten der Wasserstoffbrückenbindungen (d.h. mit der Fähigkeit zur Ausbildung von Wasserstoffbrückenbindungen mit Phenol) und beweisen, daß die Lösungsmittelabhängigkeiten wesentlich von sterischen Faktoren in der Umgebung der Carbonylgruppe abhängen. Andererseits sind die Steigungen entsprechender Korrelationen in Acetonitril/D2O — Mischungen zur Elektronendonatorfähigkeit von an das Stickstoffatom des Pyrrolidinonrings gebundenen Alkylgruppen proportional. Im Fall von Mischungen aus zwei stark wasserstoffbrückenbildenden Lösungsmitteln (Alkohole/D2O) stellt sich ein kompetitives. Gleichgewicht zwischen der Tendenz zur Wasserstoffbrückenbindungsbildung beider Lösungsmittel und den 1-substituierten 2-Pyrrolidinonen ein. In Lösungen von 1-substituierten 2-Pyrrolidinonen in 2-Butoxyethanol/D2O — Mischungen mit hohem Wasseranteil treten vor der Ausbildung klassischer Mischungen zweier polarer Flüssigkeiten mikroheterogene Domänen auf.

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.

Assessment of substituent effects for ortho-nitrobenzenes and 2,4-dinitrobenzenes by IR and 17O NMR spectroscopy

Abstract Natural abundance 17 O NMR chemical shift data in acetonitrile and infrared stretching frequency data in chloroform for 28 ortho-substituted nitrobenzenes (series I) and for 22 2,4-dinitrosubstituted benzenes (series II) are reported. A plot of 17 O NMR chemical shift data versus the infrared stretching frequency data for compounds in series I gives a graph which is interpreted as yielding two lines, one for hydrogen bonding substituents and one for non-hydrogen bonding ones. A plot of the 17 O NMR chemical shift data for the 4-nitro group of series II versus the literature values for 4-substituted nitrobenzenes gave an excellent straight line with a slope which reflected an 18% reduction in substituent effects as expected due to steric inhibition of resonance. Despite this result, correlation of the data by the dual substituent parameter approach involving σ R+ indicates that resonance effects remain important. The plot of 17 O NMR chemical shift data versus the infrared stretching frequency data for compounds in series II also gives a graph which is interpreted as yielding two lines, one for hydrogen bonding substituents and one for non-hydrogen bonding ones.

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.

Reactions of carbonyl compounds in basic solutions. Part 35

The kinetics of the alkaline hydrolysis and the configuration, conformation and electronic structure were studied using IR, NMR spectroscopy, X-ray analysis and AM1 theoretical calculations for a series of (Z)-4-(substituted benzylidene)-2-phenyl-4H-oxazol-5-ones (1) and compared with analogous results reported for (E)-4-benzylidene-2-phenyl-4H-furan-5-ones (5) and related compounds.

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.

Base‐catalysed hydrolysis of γ‐lactones: reactivity–structure correlations for 3‐(aryl‐ and alkylmethylene)‐(Z)‐1(3H)‐isobenzofuranones

Rate coefficients were measured for the base-catalysed hydrolysis of a series of γ-lactones, i.e. 39 substituted 3-(aryl- and alkylmethylene)-(Z)-1(3H)-isobenzofuranones (3-aryl- and alkylmethylenephthalides) in 70% (v/v) aqueous dioxane at 30·0 °C. A Hammett reaction constant for the 3- or 4-substituted phenyl series is ca 1·5, whereas those for the 2-substituted phenyl and 4-substituted 1-naphthyl series, using para-σ values, are ca 1·0 and 1·9. These results are related to an electrostatic field effect model. A very successful correlation between the rates of alkaline hydrolysis of all 39 phthalides and the carbonyl stretching frequencies in chloroform was found. Substituent effects in widely different environments give linearly related effects on both reactivity and physical properties. Computational studies using the semi-empirical AM1 method correctly modelled both the details of the mechanistic pathway and the substituent effects.

Identification of the isomers from mono- and dinitration of α-hydroxydiphenylacetic acid by capillary gas chromatography with Fourier transform infrared and mass spectrometric detection

Abstract All three mononitro and all six heteronuclear dinitro isomers from nitration of α-hydroxydiphenylacetic (benzilic) acid were separated as methyl esters by capillary gas chromatography and their retention indices were measured. Heteronuclear dinitro substitution of α-hydroxydiphenylacetic acid was confirmed by inspection of the MS fragmentation patterns of the eluted compounds. The mononitro and dinitro derivatives were identified on the basis of their Fourier transform IR spectra and, in part, of the MS spectra recorded in the positive-ion mode.