Search

The IR, 13C- and 17O-NMR spectral characteristics of the Cr(CO)3 group in a series of eight chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones] were correlated mutually as well as with theoretical data obtained by optimized MMX force-field and EHT calculations. The net charges on the carbon and oxygen atoms of the CO group and their differences were found as the most appropriate quantitative characteristics for the electronic properties of the Cr(CO)3 group. Using the results of the previously reported linear correlations, the electron-withdrawing effect of the PhCr(CO)3 moiety, weakened by the back-donation effect, was estimated as σα≅0.45 on the scale of Hammett substituent constants.

The infrared and 13C NMR spectra and the kinetics of alkaline hydrolysis of chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)-isobenzofuranones] have been studied in comparison with those of 3-arylmethylene-Z-1(3H)-isobenzofuranones. The 13C 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 σp 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. Charton's 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 CCl4, because a back-donation effect of the carbonyl ligands and decreases in CHCl3 due to the hydrogen bonding between carbonyl groups and solvent molecules. The preparation of some novel chromium, tricarbonyl[3-[(η6-aryl)methylene]-Z-1(3H)- isobenzofuranones] is described.

The 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 withHammet's constants of substituents and13C NMR chemical shifts of the C=O group.

Selectivity of complexation of substituted phenyl benzoates is very low. In most cases, comparable yields of both regioisomeric complexes are isolated. Exception is 4-chlorophenyl ester, where benzoic acid moiety is complexed nearly exclusively. Very high regioselectivity of complexation was observed with substituted phenyl phenylacetates. The substituent of substituted phenols has not any effect on the complexation, and only phenylacetic acid moiety is complexed. This observation supports the recently proposed mechanism of the catalytic activity of the esters at arene complexation.

The acid-catalysed complexation of various substituted phthalides with Cr(CO)6 has been studied. Complexation of substituted 3-benzylidene phthalides takes place at the phenyl ring in most cases, but with di-halogeno-substituted 3-benzylidene phthalides the complexation took place at the phthalide moiety. An explanation of this difference is based on molecular modelling quantum chemical calculations.

2-(1-Acetoxyalkylidene)- and 2-(1-acetoxybenzylidene)-1,3-indanediones (1a–1e) were proven to be the products of acetylation of 2-acyl-1,3-indanediones (2a–2e) by ketene using a detailed investigation and correlation analysis of infrared spectral data as well as1H-NMR and13C-NMR spectra. Study by means of CNDO/2 and MMPI methods also demonstrates that the structure1 is more stable as the alternative one of 2-acyl-3-acetoxy-2-indene-1-ones (5). It was shown that the recently proposed general correlations v(C=O)s vs. v(C=O)as and v(C=O) vs. ∑X+(R) as well as the mechanical anharmonicities of asymmetric C=O stretching vibration can be successfully used as a tool of structural diagnostics of cyclic 1,3-dicarbonyl compounds.

3-( N,N -dimethylamino)-2H-1-benzopyran-2-one (DMAC) exhibits a relatively strong shortlived emission (λ max ≈ 460 nm; lifetime, 0.2 ns) in non-polar solvents with a Stokes' shift of about 8000 cm −1 . In more polar solvents, the emission shifts bathochromically (Stokes' shift up to 10 000 cm −1 and lifetime of 0.5 ns). Polar protic solvents quench the fluorescence and the quenching can be quantitatively described by a Stern—Volmer dependence. The bimolecular quenching rate constants are lower than those controlled by diffusion. The monomethyl derivative 3-( N -methylamino)-2H-1-benzopyran-2-one (MAC) exhibits emission in non-polar and polar solvents which is hypsochromically shifted with respect to DMAC (λ max ≈ 400 nm; Stokes' shift around 4000 cm −1 ) and is short-lived (less than 0.1 ns). The fluorescence of DMAC and MAC originates in the intramolecular charge-transfer state.

Nucleophilic addition of alkyl-, cycloalkylamines, or saturated nitrogen-containing heterocycles to isolated or in situ generated 6-(2,3-epoxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocine (III) afforded 6-(3-substituted amino-2-hydroxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocines IV and their hydrochlorides. The starting 5,6,7,8-tetrahydrodibenz[c,e]azocine (I) reacted with 1-chloro-2,3-epoxypropane to yield 6-(3-chloro-2-hydroxypropyl)-5,6,7,8-tetrahydrodibenz[c,e]azocine (II), which, on treatment with sodium ethoxide or an excess of an amine eliminated hydrogen chloride to give the intermediate III.

A detailed investigation of infrared spectra was used to distinguish the structure of 3-(N,N-dimethylamino)coumarin from the structure of hypothetic 2-(N,N-dimethylamino)-1,3-indanedione suggested earlier as the product of the reaction between salicylaldehyde, acetanhydride and betaine.

The quantum chemical PCILO method was employed for calculation of conformational maps of 3-benzylidene-2,4-pentanedione. The analogous conformational maps of simpler substructures were also investigated to enable investigating the respective interactions. Steric interactions of the acetyl group with the phenyl group and of both acetyl groups were found to play a dominant role. One acetyl group is turned by 60° from the s-cis position, the other is in an s-trans conformation when being in the energetically more favourable sterical arrangement. The obtained data were compared with the experimental results.

Velocity of the second order rearrangement of ortho-substituted 3-(X-benzal)phthalides into respective 2-(X-phenyl)-1,3-indanediones by action of methanolic sodium methoxide has been studied spectrophotometrically. The values of logarithm of the rate constant obtained by extrapolation of the concentration dependences to zero concentration of methoxide have been correlated with σ, σ0, σ+, F, R, and Es constants of the substituents and with the Charton ν constant for the ortho-substituted derivatives. The obtained dependences log k vs the mentioned constants have been compared with the corresponding dependences of the rearrangement of the meta- and para-substituted 3-(X-benzal)phthalides into the respective 3-(X-phenyl)-1,3-indanediones. Transmission of the substituent effect on the reaction centre is almost the same from ortho and from para position. Possible ortho-effect and steric hindrance of the substituents have been followed.

13C NMR spectra of 14 derivatives of 3-(X-benzal)phthalides (I) and 10 derivatives of 2-(X-benzal)-1,3-indanediones (II) were investigated. The correlation of 13C chemical shifts of carbon atoms of the phthalide ring with σ-constants showed that the electronic effect of substituents was transmitted from the benzylidene group of 3-(X-benzal)phthalides on the chemical shift of the carbonyl group not only through oxygen, but also through the aromatic ring of the phthalide moiety. The transmission of substituent effects in 2-(X-benzal)-1,3-indanediones on the chemical shift of the carbonyl groups was more pronounced on the carbonyl, which is in the trans-arrangement with respect to the aryl group. This phenomenon was also observed at carbon atoms of the benzene ring of the indanedione moiety closer to the trans-CO group.

The 1H-NMR spectra of ortho-substituted 2-(X-benzal)-1,3-indanediones, 3-(2-X-benzal)-phthalides and 3-(2-X-benzal)-5,6-dihydro-4,7-dithiaphthalides have been studied. The chemical shifts observed for the methine proton were correlated with various constants of the substituents. In addition to simple correlations, two- and three-parameter correlations were also made. Statistically most important one-parameter correlations were observed for σp-constants. Apart from the common electronic effects, in the transfer of effects of the substituents from the ortho-position upon the chemical shift of the methine proton the field effect plays also an important role. The deviations observed in the case of substances substituted in both ortho-positions confirm the assumed considerable distortion of the coplanarity of the studied systems.

2- N,N -dimethylamino-1,3-indanedione (DMAI) undergoes demethylation during photolysis (λ > 290 nm), producing 2- N -methylamino-1,3-indanedione (MAI) under conditions of direct or sensitized reaction. Ferrocene successfully quenches demethylation, while ethyl iodide accelerates the reaction rate. The yield and the rate of formation of MAI strongly depend on the reaction conditions, mainly on the solvent, the concentration of DMAI and the presence of an electron acceptor (substituted nitrobenzene). The UV, IR and NMR spectra support the donor—acceptor intramolecular interpretation in the ground state of DMAI and MAI.

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

3-( N , N -dimethylamino)-2 H -benzopyran-2-one (DMAC) sensitizes the decomposition of CCl 4 during the photolysis in the near UV region (λ > 290 nm). The products of the photolysis are 3-( N -methylamino)-2 H -1-benzopyran-2-one (MAC) as a result of the demethylation of DMAC and the compounds formed by the reaction of DMAC with the trichloromethyl radical 3-( N , N -dimethylamino)-3,4-bis(trichloromethyl)-2 H -3,4-dihydrobenzopyran-2-one and hydrochloride DMAC. Recombination of ·CCl 3 radicals yields hexachloroethane. The ratio of the products depends on the reaction conditions (the concentration of DMAC, the light intensity and the temperature). The primary step in the mechanism of the sensitization of CCl 4 is assumed to be the formation of the excited state, charge transfer (CT) complex of the type DMAC δ+ …CCl 4 δ− . Chloromethanes CH x Cl 4− x ( x = 0,1,2) quench the fluorescence of DMAC and MAC. The Stern—Volmer constant for MAC is related to the electron affinity of chloromethanes.

Fundamental CO and CC stretching frequencies and carbonyl first overtones of substituted 3-benzylidene-2,4-pentanediones were measured in CCl 4 and CHCl 3 . The data are correlated with substituent constants and carbonyl stretching frequencies of corresponding substituted acetophenones. By investigating the effect of substituents, solvents, temperature and anharmonicity as well as the i.r. data of model compounds, the absorption bands were assigned to the vibrations of structural groups. Evidence was obtained that 3-benzylidene-2,4-pentanediones in liquid or solid state and in organic solvents exist in two quasi planar conformations I and II .

Substituent effects on the 13C and 1H chemical shifts have been studied for derivatives of 3-benzylidene-2, 4-pentanedione. A significant correlation has been found between chemical shifts of the Z carbonyl group (C-2) and Hammett constants, while no correlation has been found for the E carbonyl group (C-4). Attempts have been made to determine the structural factors which influence these effects. The conformation of 3-benzylidene-2, 4-pentanediones has been determined by 13C and 1H NMR spectroscopy.

29Si chemical shifts are reported for nine 1,2-bis(trimethylsiloxy)cycloalkenes and four 1-trimethylsiloxycycloalkenes, (Me3SiO)xCnH2n–2–x (x=1, 2). For cycloalkene derivatives with n⩽8 the silicon shift exhibits a strong dependence on the ring size, although the silicon is exocyclic and is separated by two bonds from the olefinic carbon atom. The dependence can be exploited for ring size determination of cyclic ketones after trimethylsilylation.

The reaction of salicylaldehyde, betaine and acetic anhydride gives 3-(N,N-dimethylamino)-2H-1-benzopyran-2-one in contrast with the published 2-(N,N-dimethylamino)-1,3-indandione.