Effect of fluoromethyl substituents on the spectral properties of the benzene ring

The electronic spectra of benzyl fluoride, benzal fluoride, and benzotrifluoride have been studied in polarized light at 4 K. An attempt is made to interpret the special features observed in the spectra by associating them with the effect of the different fluoromethyl substituents.     

Introduction of substituents into the benzene ring of indole

A number of dinitro-2-methylindolines (5,6-, 6,7-, and 5,7-) were synthesized by the nitration of nitro-2-methylindoline isomers. The positions of the nitro groups in each case were proved by means of NMR and electronic spectra.See [6] for communication XII.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 953–955, July, 1971.     

Synthesis of aromatic isothiourea compounds containing substituents in the benzene ring

Conclusions Arylation of thiourea with aryldiazonium borofluorides containing substituents in the benzene ring yielded isothiourea compounds containing halogen atoms, the nitro group, and the isothiourea group in the ring.Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1910–1913, August, 1968.     

Effect of methyl substituents on the NMR spectra of aromatic protons of some nitrobenzene derivatives

Proton NMR spectra were recorded and analysed for 1-bromo-4-nitrobenzene, 2-bromo-5-nitroluene, 3-bromo-6-nitrotoluene and 2-bromo-5-nitro-p-xylene, as well as for the corresponding compounds having p-CH₃C₆H₄S in place of Br. Chemical shifts and coupling constants generally agree with expected values; however, a deshielding effect of the methyl group on aromatic protons was observed in one case.     

Effect of substituents on the chemical shift of the ring protons in the PMR spectra of monosubstituted sym-triazines

A correlation equation that links the relative chemical shift of the protons of the triazine ring with the F and R constants of the substituents was obtained on the basis of data from the PMR spectra of solutions of sym-triazine and its monosubstituted derivatives [OCH₃, N(CH₃)₂, CH₃, C₆H₅, COOC₂H₅, and CN] in dimethyl sulfoxide (DMSO). The equation was analyzed by comparison with the corresponding equations for monosubstituted benzenes and pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–414, March, 1982.     

NMR spectra of 1,3,5-triazines with fluorinated substituents

The NMR spectra of a series of 1,3,5-triazines (1) in which one or more of the substituent groups are fluorinated are described, and the results are discussed in terms of bonding and geometry of the molecules. Remote effects of unsymmetrical substitution are observed in the fluorine-19 and carbon-13 spectra, in some molecules indicating restricted rotation about the bond joining an amino group to a ring carbon.     

Photochromism of 3H-2,1,4-benzoxadiazine 4-oxides with heterocyclic substituents on the benzene ring

Russian Journal of Organic Chemistry - 2H-Benzimidazole 1,3-dioxides undergo thermal isomerization to 3H-2,1,4-benzoxadiazine 4-oxides which are converted to 2H-benzimidazole 1-oxides on further...     

Luminescence studies of europium chelates with increasing benzene ring substituents ligand-doped polymer

The luminescence properties of four europium chelates with increasing benzene ring substituents ligand in poly(methylmethacrylate) (PMMA) have been investigated by fluorescence emission spectra and lifetime measurements. According to the fluorescence emission spectra, the Judd-Ofelt parameters Omega2, Omega4 of europium chelates-doped PMMA have been calculated and the radiative properties were also presented. It showed that the increase of benzene ring substituents in ligand can increase the metastable state lifetime tau(m), the luminescence quantum yield eta and the stimulated emission cross-section sigma of 5D0-->7F2 transition.     

A novel ring transformation of uracil into the benzene ring system

Reaction of 5-formyl-1,3-dimethyluracil with some active methylene compounds in the presence of base causes novel ring transformations to give the p-hydroxybenzoates and the nicotinate.     

13C NMR spectra of N-substituted carbazoles. Transmission of the electronic effects of substituents through the nitrogen atom to the carbazole ring

The effect of substituents attached to the nitrogen atom on the ¹³C NMR chemical shifts was determined for a series of 9-substituted carbazoles. Correlation relationships between the inductive and resonance constants of the substituents and the chemical shifts of the carbon atoms were obtained. It was shown that carbazole derivatives are similar to anilines with respect to the conductivity of electronic effects through the nitrogen atom to the carbazole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1184–1188, September, 1986.The authors thank N. V. Moskalev for providing them with a sample of carbazole Im.     

Effect of substituents on the fluorescence and absorption spectra of coumarins

The absorption and fluorescence emission of substituted coumarins have been studied in different solvents. It is observed that the substituents alter both the absorption and fluorescence emission maxima. These shifts are discussed in terms of the change in mobility of π-electrons caused by the nature and position of the substituent group in the parent compound.     

On the1H NMR spectra of biliverdins with free propionic acid substituents

Summary The¹H NMR spectra of Biliverdin IX and Mesobiliverdin XIII were studied in order to explain their low resolution in CDCl₃/CD₃OD solvent mixtures. The smallT ₂ andT ₁ values of these¹H NMR spectra are probably due to aggregate formation promoted by the presence of the free propionic acid substituents.

---

¹H-NMR-Spektren von mit freien Propionsäureresten substituierten Biliverdinen

Zusammenfassung Es wurden die¹H-NMR-Spektren von Biliverdin IX und Mesobiliverdin XIII untersucht. In CDCl₃/CD₃OD-Mischungen erhält man eine schlechte Auflösung. Die niedrigenT ₁-undT ₂-Werte lassen sich durch eine Aggregatbildung erklären, die durch die freien Propionsäuregruppen verursacht wird.

     

Synthetic approaches toward ecteinascidins. Part 2. Preparation of the ABCDE ring system of ecteinascidins having characteristic substituents in both benzene rings

A synthesis of an advanced ABCDE ring system (24c) having characteristic substituents in both benzene rings of ecteinascidin marine natural products is described based on our model studies.     

Topological simulation of13C NMR spectra of polyoxy derivatives of benzene

Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 51–60, January–February, 1992.     

Effect of substituents in the ring on the structure and electron density distribution in benzyl halides

The results of calculations for benzyl chlorides and benzyl bromides that contain substituents in the ring by different quantum-chemical methods are compared. The electron density on the benzyl carbon atom increases as the electron-withdrawing properties of substituents are enhanced due to the shift of the electron density from the benzyl halogen atom to the adjacent carbon atom. A topological analysis according to Bader confirmed the main reason for the change in the paramagnetic shielding of the benzyl¹³C nuclei. The results of calculations provide, for the first time, an explanation for the resonance upfield¹³C shift of this atom as the Hammett constant of a substituent increases in compounds of the series under consideration. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2111–2119, December, 1997.     

Synthesis of [1]benzothieno[3,2-d]pyrimidines substituted with electron donating substituents on the benzene ring

Various 2-fluorobenzonitriles were converted to the corresponding 3-amino[1]benzothiophenecarboxylic acid esters, which in turn were annulated with formamidine or various equivalents to produce the desired tricyclic benzothienopyrimidines. Various methoxy and nitro/amino substituents were placed on the phenyl ring, requiring several different strategies to prepare the desired benzothiophenes. Several different pyrimidone annulations were also required. The use of an electron rich 2-bromobenzonitrile in a four-step one-pot low temperature lithiation sequence to produce highly electron-rich amino[1]benzothiophenecarboxylate esters is also described. The synthesis of 7-amino-8-fluoro[1]benzothieno[3,2-d]pyriinid-4(3H)-one was relatively straightforward, but synthesis of the corresponding 7-amino-8-protio analogue proved to be very difficult, and required several approaches before a successful one was found.