F and C spectra of fluorinated and partially fluorinated vinyl alkyl ethers

Fluorine, hydrogen, and ¹³C NMR spectral data have been obtained for vinyl alkyl ethers containing fluorines. Some of the molecules are perfluorinated and others include hydrogen, bromine, and chlorine substituents. New generalizations regarding FF spin-spin coupling are developed and used, along with previously recognized correlations, in the confirmation of structures and the assignments of resonances. ¹³C spectroscopy, especially the analysis of ¹³C¹⁹F coupling, is critical in several of the structure determinations. Chlorine isotope effects on fluorine chemical shifts are observed when the chlorine and fluorine are attached to the same carbon, and are also used in the structure analyses. Long-range couplings between fluorines in the vinyl group and fluorines in the alkyl group are interpreted in terms of molecular geometry which allows certain of the alkyl fluorines to “touch” the fluorines cis and gem to the ether oxygen but not the fluorine trans to the oxygen. Two bond ¹³C¹⁹F coupling across the vinyl double bond is found to vary dramatically with the electronegativity of the vinyl substituents in the ethers, in accordance with previous observations for olefins.     

Study of C-H...N specific intramolecular interactions in heteroaryl vinyl ethers,by means of regression and cluster analysis of parameters of1H and13C NMR parameters

By means of regression and cluster analysis of the parameters of the¹ and¹³C NMR spectra of the vinyloxy group in a broad series of aryl and heteroaryl vinyl ethers, it has been proven statistically that these parameters are abnormal for ethers in which the vinyloxy group occupies a position adjacent to an endocyclic nitrogen atom; this is evidence for the existence of a C-H...N specific intramolecular interaction between the -hydrogen atoms of the vinyl group and the endocyclic nitrogen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1344–1351, June, 1991.     

Relative thermodynamic stabilities of allyl vinyl and propenyl vinyl ethers

The relative thermodynamic stabilities of a number of isomeric allyl vinyl and propenyl vinyl ethers were determined by chemical equilibration in DMSO solution with KOBu-t as catalyst. From the temperature dependence of the values of the equilibrium constant the parameters G _m , H _m and S _m of isomerization at 298.15 K were evaluated. Propenyl vinyl ethers, owing to their low enthalpy contents, are much more stable than the isomeric allyl vinyl ethers. It appears that in the parent propenyl vinyl ether, the Me group attached to C- of the divinyl ether skeleton has a strong stabilizing effect, comparable to that of alkyl groups in ordinary olefins, on the unsaturated system. In more heavily alkyl-substituted divinyl ethers, however, the stabilizing effects of alkyl groups are less prominent, being comparable to the low stabilization energies of alkyl groups in vinyl ethers, and depend moreover, on the pattern of substitution.     

End-Functionalized polymers by living cationic polymerization. IV. Poly(vinyl ethers) with acidic or basic terminal groups by functional initiator method

Carboxylic acid or primary amine-terminated poly(isobutyl vinyl ethers) were synthesized by living cationic polymerizations with functionalized initiators (CH₃CHIO? CH₂CH₂ ? X; X: that are the adducts of the corresponding vinyl ethers (CH₂ ? CH ? OCH₂CH₂? X) with hydrogen iodide. In the presence of iodine, these initiators induced living cationic polymerization of isobutyl vinyl ether to give polymers with the α-end group of X originating from the initiators. The polymer molecular weights were regulated by the monomer to initiator feed ratio and the molecular weight distributions were very narrow (M _w/M _n ≤ 1.15). Subsequent deprotection of the terminal group X led to polymers with a terminal carboxylic acid or primary amine. ¹H- and ¹³C-NMR analyses showed that the end functionalities of these polymers were all close to unity.     

Investigation of electronic structure of allenyl ethers by means of photoelectron and UV spectroscopy

A study of the photoelectron spectra of alkyl allenyl ethers has demonstrated their similarity to spectra of alkyl vinyl ethers, with the exception of a band in the 10.0–10.3 eV interval due to ionization of the -orbital of the allenyl fragment C=C. According to data obtained by photoelectron spectroscopy and MNDO quantum-chemical calculations, alkyl allenyl ethers with straightchain substituents exist primarily in the s-cis conformation. The stable conformation of allenyl tert-butyl ether is the s-trans form. The long-wave absorption bands in the UV spectra of alkyl allenyl ethers at 255–275 and 208–213 nm are assigned to electronic transitions of the ^* and ^{* *} types; these are quite insensitive to s-cis/s-trans isomerism.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 81–88, January, 1990.The authors are extremely grateful to V. K. Turchaninov for assistance in interpreting the spectra.     

Reaction of the vinyl ethers of heterocyclic imino alcohols with acyl halides

Conclusions The reaction of the vinyl ethers of heterocyclic imino alcohols with acyl halides gave a number of new vinyl ethers of heterocyclic amido alcohols as 11 mixtures of the isomeric 3,6- and 5,6-dihydropyrans, and ³- and ⁴-piperidines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2538–2541, November, 1980.     

Sequence-regulated oligomers and polymers by living cationic polymerization. III. Synthesis and reactions of sequence-regulated oligomers with a polymerizable group

New sequence-regulated macromonomers ( 3 ) with a vinyl ether terminal were prepared by the HI/ZnI₂-mediated living cationic polymerization of vinyl ethers: CH₃? CH(OR¹)? CH₂CH(OR²)? C(COOEt)₂CH₂CH₂OCH?CH₂ ( 3a : R¹ = nBu, R² = CH₂CH₂OCOPh; 3b : R¹ = iOct, R² = CH₂CH₂Cl). The synthesis consisted of three consecutive steps: (i) quantitative addition of hydrogen iodide to the first vinyl ether into an adduct [CH₃? CH(OR¹)? l]; (ii) propagation of a second vinyl ether from the adduct in the presence of zinc iodide; and (iii) quenching the resulting AB-type heterodimeric living intermediate with a carbanion [^θC(COOEt)₂CH₂CH₂OCH?CH₂] carrying a vinyl ether group. The HI/ZnI₂-initiated living cationic polymerization of 3a and 3b yielded narrowly distributed polymers $\left( {\overline {DP}} _{_n } \sim 10 \right)$ consisting of a poly(vinyl ether) backbone and sequence-regulated oligomer branches. The terminal vinyl ether function of 3 was also utilized to prepare pentamers and hexamers with controlled sequence of functional vinyl ethers by selective dimerization and chain extension reactions with HI/ZnI₂. © 1993 John Wiley & Sons, Inc.     

15N and17O NMR spectra of vinyl ethers of pyridine and quinoline

Conclusions ¹⁵N (¹⁴N) and¹⁷O NMR spectra have been obtained on vinyl ethers of pyridine and quinoline, with unenriched samples. The principal factor determining the chemical shifts is p- conjugation of the unshared pairs of the heteroatom with the unsaturated fragments of the molecule; an additional contribution in the case of the¹⁵N signals comes from interaction of the nitrogen atom with a proton through space.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 769–773, April, 1987.     

Decomposition of vinyl ethers by alkalide K, K(15-crown-5)2 via organopotassium intermediates

The structure of vinyl ethers determines the direction of the C-O bond cleavage by alkalide K⁻, K⁺(15-crown-5)₂1. Highly reactive organopotassium compounds are intermediate products formed in the system containing phenyl vinyl ether, butyl vinyl ether, ethylene glycol butyl vinyl ether or triethylene glycol methyl vinyl ether. Vinylpotassium and butylpotassium react with 15-crown-5. The oxacyclic ring of the latter is opened in this case. Organopotassium ethers possessing CH₂CH₂O units eliminate ethylene. It results in various potassium alkoxides. The reaction of 1 with butyl vinyl ether occurs very slow as compared to other vinyl ethers and most of other reagents used till now.     

9-alkenylcarbazoles

The¹H and¹³C NMR spectra of 9-vinylcarbazole and its 3-chloro, 3,6-dichloro, and 3-nitro derivatives were recorded and studied. It is shown that electron-acceptor substituents reduce the shielding of the -carbon atom and the trans proton of the vinyl group. A good linear correlation between the chemical shifts of these nuclei and the Hammett _para ^– constants with the values (3.78 for¹³C and 0.28 for¹H_trans) is observed. It was established by comparison of the results with the¹H and¹³C NMR spectral parameters for some of the vinyl compounds that the degree of conjugation of the p electrons of nitrogen with the electrons of the double bond in 9-vinylcarbazoles is lower than in simple vinyl and vinyl phenyl ethers and vinyl acetate.See [25] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1368–1371, October, 1976.     

Calculation of the torsional angles in alkyl vinyl ethers from the direct13C-1H spin-spin interaction constants

It is shown that the differences in the direct¹³C-¹H SSIC of the C atom of the vinyl groups in alkyl vinyl ethers depend on the value of the torsional angle about the C bond. This dependence is used to make quantitative estimates of the torsional angles in alkyl vinyl ethers with alkyl substituents ranging from CH₃ to t-C₄H₉ Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 390–393, February, 1991.The authors are grateful to S. V. Kirpichenko for providing the triethylvinylthiosilane, synthesized as described in [11].     

Study of three-dimensional structures of benzoylpyridine oximes and their ethers by 1H and 13C NMR spectroscopy

The ¹H and ¹³C NMR spectra of the E and Z isomers of 2-, 3-, and 4-benzoylpyridine oximes and their ethers were analyzed thoroughly, and the ¹H-¹³C spin-spin coupling constants (SSCC) were determined. It was established that the magnitude of the effect for the quaternary carbon atoms in the E and Z isomers depends on the site of substitution in the pyridine ring. It was assumed that the intermolecular hydrogen bond is stronger in the E form than in the Z form. The existence of the Z isomer of 2-benzoylpyridine oxime in deuterochloroform with an intramolecular hydrogen bond was proved.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 203–208, February, 1990.     

1-Methyl-2(3,4)-(1-vinylpyrrol-2-yl)pyridinium iodides: some structural features revealed by 1H and 13C NMR spectroscopy

The reactions of 2-, 3-, and 4-(1-vinylpyrrol-2-yl)pyridines with methyl iodide afford the corresponding quaternary salts. Analysis of their ¹H and ¹³C NMR spectra showed that the quaternization of the nitrogen atom considerably enhances the -acceptor effect of the pyridine ring on the pyrrole ring and on the vinyl group. 1-Methyl-2-(1-vinylpyrrol-2-yl)pyridinium iodide contains no weak intramolecular C--H...N hydrogen bond present in the starting compound.     

Reactivities and NMR spectra of vinyl ethers

Copolymerizations of n-butyl vinyl ether (M₁) with other vinyl ethers were carried out in toluene at ?78°C with EtAlCl₂ catalyst and the monomer reactivity ratios were determined. It was found that the relative reactivity of alkyl vinyl ether log 1/r₁ is higher when the alkyl group is more electron-donating and the reactivity correlates linearly with the Taft σ^* of alkyl group in the monomer. The NMR spectra of vinyl ethers and of vinyl ether–trialkylaluminum complexes were investigated. Close correlations were found between the spectral characteristics and the relative reactivity of vinyl ether in the copolymerization. The degree of resonance contribution in alkyl vinyl ether was also discussed on the basis of NMR data.     

Determination of structure and concentration of growing species in ionic polymerizations: The 31P NMR method

The quantitative transformation of the ionic growing species (∼ ∼ ∼*) into the P atom containing end-groups (∼ ∼ ∼P) allows to determine by ³¹P NMR their structures and concentrations, down to 10⁻⁴ mol-L⁻¹, or even lower with a further progress of the NMR equipment: The P atoms are exclusively located at the chain ends, the known excess of the reagent “P” being used as an internal standard. The chemical shifts of thus prepared chain ends, when compared with models, give information on the chemical structure of the parent active species. This paper reviews the earlier work on ionic ring-opening polymerization and more recent work, concerning cationic and anionic vinyl polymerization, particularly polymerization of vinyl ethers, styrene, methacrylates and some diene monomers. In the polymerization of vinyl ethers the stereochemistry of the chain ends was studied; it has also been shown, that chemical shift changes with the polymerization degree; thus the first addition products could separately be observed.     

Hydroxyl radical,sulfate radical and nitrate radical reactivity towards crown ethers in aqueous solutions

Reaction rate constants of crown ethers (12-crown-4, 15-crown-5, 18-crown-6) and their analogs 1,4-dioxane (6C2) with some important oxidative radicals, hydroxyl radical (OH), sulfate radical (SO₄^?) and nitrate radical (NO₃), were determined in various aqueous solutions by pulse radiolysis and laser photolysis techniques. The reaction rate constants for 6C2 and crown ethers with OH and SO₄^? increase with the number of hydrogen atoms in the ethers, indicating that the hydrogen-atom abstraction is a dominant reaction between crown ethers and these two radicals. The presence of cations in solution has negligible effect on the rate constants of crown ether towards OH and SO₄^?. However, for the NO₃, the rate constants are not proportional to the number of hydrogen atoms in ethers, and 12-crown-4 (12C4) is the most reactive compared with other crown ethers. Except 12C4 and 6C2, the cations in the aqueous solution affect the reactivities of 15-crown-5 (15C5) and 18-crown-6 (18C6). The cations with high binding stability for crown ether would improve the reactivity of 15C5. For the studied crown ethers, the reaction rate constants of these oxidative radicals have the order OH>SO₄^?>NO₃. Furthermore, the formation of radicals after the reaction of crown ethers with sulfate radical could be observed in the range of 260–280 nm using laser photolysis and pulse radiolysis. This is the first report on the kinetic behavior of crown ethers with NO₃, and it would be helpful for the understanding of stability of crown ethers in the processing of spent nuclear fuel.     

N-Isopropenylazoles: I. Direct N-Isopropenylation of Azoles with Propyne and Allene

A number of previously unknown N-isopropenyl-substituted pyrroles, indoles, and di- and -triazoles were synthesized in 20-86% yield by reaction of the corresponding azole with an equilibrium mixture of propyne with allene or pure propyne and allene in the system KOH-DMSO (105-145°C, 5-15 h, atmospheric or elevated pressure). The reaction is regioselective. The electronic and steric structure and the degree of conjugation between the exocyclic double bond and the azole ring are discussed on the basis of the ¹H and ¹³C NMR spectra. Almost complete absence of p- conjugation in ,'-disubstituted N-isopropenylazoles have been found.     

Hydroxyl Protection. III. Synthesis and Cleavage of 2-(Phenylseleno)Ethyl Ethers

During a quest of new hydroxyl-protecting groups, our attention was focused at one time on the 2-(phenylseleno)ethyl residue. It has been established that selenides are responsive to oxidation by H₂ O ₂,² O ₃,³IO₄,⁴etc., to afford selenoxides; aryl alkyl selenoxides undergo facile thermal decomposition⁵ at room temperature or below. Thus starting from 2-(phenylseleno)ethyl ethers (1), the reaction sequence would lead to vinyl ethers and PhSeOH via the intermediates (2). As vinyl ethers are easily hydrolyzed on contact with mineral acids to acetaldehyde and alcohols, the value of the PhSeCH₂CH₂ group for blocking hydroxyl becomes clear.     

Study of specific C-H...N intramolecular interactions in heteroaryl vinyl ethers,on the basis of factor analysis of1H and13C NMR spectral parameters

On the basis of a factor analysis of the¹H and¹³C NMR spectral parameters of the vinyloxy group in a broad series of aryl and heteroaryl vinyl ethers, it has been established that these parameters change mainly under the influence of the electronic effect of the aromatic fragment and specific C-H...N intramolecular interaction of the -hydrogen atoms of the vinyl group with an endocyclic nitrogen atom. It has been shown that the parameters most sensitive to the specific C-H...N. interaction are the chemical shifts of the -proton and -carbon of the vinyl group, and also the spin-spin coupling constant between these atoms.Translated from Izvestiya Akademii Nauk SSSR, No. 10, pp. 2289–2297, October, 1991.     

Spectroscopic effects and intramolecular interactions in the1H and13C NMR spectra of five-membered N-vinyllactams

In 1-vinylpyrrolidone, 1-vinyl-1,2,4-triazole-5-ones, 1,3-divinylimidazolidine-2-thione, and 1-vinylbenzimidazole-1-thione the vinyl groups exist predominantly in the s-trans-, but in 1-vinyl-4,5-diphenylimidazole-2-ones in the s-cis(0)-conformations relative to the exocyclic heteroatom. In 1-vinylbenzimidazole-2-ones, 3-vinylbenzoxazole-2-one, and 1-vinylindole-2,3-diones the vinyl group is present as a mixture of the s-cis(0)- and s-trans(0)-conformations. According to¹H and¹³C NMR results there are specific intramolecular interactions in 1-vinylpyrrolidone and in 1,3-divinylimidazolidine-2-thione resembling weak hydrogen bonding between the -hydrogen atoms of the vinyl group and the oxygen or the sulfur atom. In 1-vinylsuccinimide, 2-vinylphthalimide, and 1,3-divinyl-4,5-diphenylimidazole-2-one there is the same type of interaction with the -cis-hydrogen atom of the vinyl group, while in 1,3-divinyl-1,2,4-triazole-5-one there is interaction between the same hydrogen atom and the nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1983–1990, September, 1990.