Infrared spectra of cyclic ethers and their derivatives

Data for the characteristic bands of cyclic ethers are reviewed. The infrared spectra of a number of 2-mono- and 2, 5-di-substituted derivatives of tetrahydrofuran are investigated. Absorption bands at about 900 cm⁻¹ are related to pulsation vibrations, and those at about 1200 cm⁻¹ to antisymmetric skeletal vibrations, of the tetrahydrofuran ring. It is shown that to confirm the presence of a tetrahydrofuran ring in a molecule, it is necessary to take into account not only the band of valence antisymmetric vibrations of the group C-O-C (ν _C-O-C ^as 1075 cm⁻¹), but also bands due to ring pulsation vibrations (ring symmetric valence vibrations ν _sk ^s ∼ 900 cm¹).     

The mass spectra of some cyclic ethers

The mass spectral fragmentations of the saturated five-, six- and seven-membered ring ethers have been determined by studying their site-specifically deuterated analogues by both high and low-resolution mass spectrometry. The initial processes, governing the fragmentations of the cyclic ethers are shown to be identical with the well-known processes of linear nonbranched ethers, i.e. predominant α-fisson in the lower members and predominant carbon-oxygen fisson with charge retention on the carbon atom in the higher members.     

Infrared spectra of nitrostyrene derivatives

The IR spectra of a series of 6 phenylnitroethenes (PNE) and 6 phenylnitropropenes (PNP) were assigned, based on a normal coordinates calculation performed on styrene and styrene-d₈. Some frequencies were sensitive to the electronic properties of the substituents, and others to the substitution on Cβ. AM1 minimum energy conformations and rotational barriers around the ClCα bond were calculated. According to these calculations, PNE are planar and PNP display an angle of 45° between the ethylenic and aromatic planes. AM1 underestimates the height of the electronic barriers, which is however modulated by the electron donor properties of the substituent on the ring. A correlation between the calculated electronic barrier and the CC ethylenic stretching frequency was observed.     

Infrared spectra and rotational isomerism of certain crystalline vinyl ethers

Conclusions In contrast to conformationally inhomogeneous liquid vinyl ethers, crystalline trialkylvinyloxyalkylammonium salts, according to the data of IR spectroscopy, exist practically only in the form of a flat (conjugated) conformation. An exception is trimethylvinyloxyethylammonium bromide, which crystallizes almost exclusively in a nonplanar form.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1457–1460, July, 1971.     

Radical reaction of trinitromethane derivatives with cyclic ethers

Conclusions The photolysis of solutions of C(NO₂)₄, IC(NO₂)₃ and CH(NO₂)₃ in tetrahydrofuran and tetrahydropyran at 20° leads to the formation of the corresponding-trinitromethyl derivatives of cyclic ethers. Data were obtained in support of a radical nonchain reaction mechanism.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1149–1151, May, 1973.     

Infrared spectra of triorganoacyloxysilanes and their isologs

Conclusions An analysis of the IR spectra of the compounds R₃MOCOR, where R and R=CH₃, C₂H₅ or C₆H₅, testify to a competition between , p-conjugation and d–p-interaction in the M-O bond (for M=Si, Ge), and to the formation of M...O coordination bonds (for M=Sn, Pb).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 164–166, January, 1971.     

Difluoronitroethyl ethers of 1,2-alkylene glycols and their derivatives

Conclusions A method was developed for the preparation of the 2,2-difluoro-2-nitroethyl ethers of 1,2-alkylene glycols by reacting 2,2-difluoro-2-nitroethanol with the appropriate olefin -oxides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1448–1450, June, 1975.     

PMR spectra of catechins and their derivatives

Summary The PMR spectra of catechins, gallocatechins, epigallocatechin gallate, and their acetyl derivatives have been analyzed and the structures of the compounds investigated have been confirmed.The parameters of the signals of the H-2 and H-3 protons that have been found and also the nature of their change on acetylation enable a compound investigated to be assigned unambiguously to the normal or to the epi series.Division of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 46–50, January–February, 1976.