Mass spectra of some perfluoroalkyl and perfluoroalkylether substituted 1,3,4-oxadiazoles

Electron impact fragmentation patterns were obtained for 2,5-bis-(perfluoroalkyl)-, 2,5-bis(perfluoroalkylether)-, and 2-perfluoroalkylether-5-perfluoroalkyl-1,3,4-oxadiazoles. All compounds gave parent ions. Cleavage β to the oxadiazole ring occurred preferentially; however, cleavage α to the ring also took place. Fragmentation of the ring was accompanied by the loss of a fragment of mass 28; this was most evident in the case of 2,5-bis(perfluoro-n-heptyl)-1,3,4-oxadiazole.     

Mass spectra of some perfluoroalkyl and perfluoroalkylether substituted 1,2,4-oxadiazoles

Electron impact fragmentation patterns were obtained for 1,4-bis[(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl]-benzene, its perfluoroalkylether substituted analogue, 3,5-bis(perfluoroalkyl)-, 3,5-bis(perfluoroalkylether)- and 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazoles. In the compounds containing the phenylene group the molecular ion constituted the base peak; the main process was the breakdown of the oxadiazole ring with concurrent liberation of the perfluoroalkyl or perfluoroalkylether nitrile molecule; cleavage of the fluorinated chain α to the oxadiazole ring was found to take place to a considerable degree. In the perfluorinated 1,2,4-oxadiazoles cleavage β to the oxadiazole ring occurred preferentially; fragmentation of the ring itself took place to a limited degree only. The 3-perfluoroalkylether-5-perfluoroalkyl-1,2,4-oxadiazole appeared to undergo the primary β-cleavage exclusively at the perfluoroalkylether sidechain.     

Mass spectra of bis-π-allylic-palladium halides

The mass spectral fragmentation of (π-allyl-PdCl)₂, (π-methallyl-PdCl)₂, (π-crotyl-PdCl)₂ and (π-allyl-PdBr)₂, (π-methallyl-PdBr)₂, (π-crotyl-PdBr)₂ are described and discussed. It is shown that the breakdown of these complexes after ionization depends on the nature of the groups attached to the metal.     

Preparation of perfluoroalkylthiohydroximates from perfluoroalkyl nitriles

S-Methyl($\text{Z}$)-2,2,2-trifluorothioacetohydroximate ($\text{1}$), S-methyl($\text{Z}$)-2,2,3,3,3-pentafluorothiopropiohydroximate ($\text{2}$), and S-methyl($\text{Z}$)-2,2,3,3,4,4,4-heptafluorothiobutyrohydroximate ($\text{3}$) were prepared by reaction of the corresponding perfluoroalkyl nitriles $\text{4}$, $\text{5}$, and $\text{6}$ with methanethiol and hydroxylamine hydrochloride.     

Oxidative properties of perfluoroalkyl halides

On the basis of half-wave potential values E_1/2 it was shown that perfluoroalkyl halides have pronounced oxidative properties in comparison with unfluorinated analogs. Tertiary perfluoroalkyl iodides, having a higher oxidation potential than iodine, react with I^– by a scheme including one-electron transfer.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2222–2224, October, 1989.     

Synthesis and some properties of tertiary perfluoroalkyl halides

It is shown for the first time that bromination and iodination of tertiary perfluorocarbanions are reversible. The tendency of teriary perfluoroalkyl halides to undergo dehalofluorination under the influence of weak bases depends on the structure of the perfluoroalkyl halide, and increases in going from lower to higher halides and from linear to cyclic compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 636–640, March, 1990.     

Reaction of dialkyldithiotrimethylsilylphosphites with acyl halides

It has been established that S,S-dialkyltrimethylsilyldithiophosphites react with acyl halides in two directions, depending on the nature of the halogen in the acyl halide and on the reaction conditions, thus giving as the main reaction products either dialkyldithiohalophosphites or dialkyldithioacylphosphonates. The latter compounds react with acyl halides in accordance with a retro-Arbuzov reaction scheme, giving dialkyldithiohalophosphites.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, Kazan 420083. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 1011–1016, April, 1992.     

Sequential perfluoroalkylation and asymmetric reduction of nitriles triggered with perfluoroalkyl titanates: catalytic asymmetric synthesis of perfluoroalkyl amines

Highly enantio-enriched perfluoroalkyl amines are shown to be synthesized by perfluoroalkylation and asymmetric reduction of nitriles. Perfluoroalkylation of nitriles can be attained by the Lewis acidic perfluoroalkyl titanate reagents to give acyclic ketimines. Catalytic asymmetric hydrogenation of the acyclic ketimines affords the perfluoroalkyl amine products in up to 93% ee.     

Mass spectra of acyl and α-hydroxyalkyl derivatives of biferrocene

The mass spectral fragmentation pathways of acyl and α-hydroxyalkyl derivatives of biferrocene and related compounds are presented. A substituent effect for the cleavage of the cyclopentadienyl ring-metal bonds has been found in the spectra of acyl derivatives. It has been shown that the fragmentation of α-hydroxyalkyl derivatives proceeded via the ions corresponding to the [M]⁺? ions of oxidation or hydrogenolysis products of the hydroxyl derivatives.     

Photochemical reactions of acyl iodides with aryl halides

Photochemical reactions of acyl iodides RC(O)I (R = Me, Ph) with aryl halides, fluoro-, chloro-, and bromobenzenes, 1,4-dibromobenzene, 2- and 3-bromotoluenes, and 4-bromo-1,2-dimethylbenzene, were studied. Acetyl iodide reacted with chloro- and bromobenzenes and 1,4-dibromobenzene according to the exchange pattern to give iodobenzene and 1,4-diiodobenzene, respectively. No halogen exchange was observed in the reactions of acetyl iodide with fluorobenzene and hexafluorobenzene. Benzoyl iodide failed to react with chloro- and brombenzene under UV irradiation but underwent polycondensation with formation of black nonfusible oligomers which were found to possess paramagnetic and semiconducting properties. Ultraviolet irradiation of a mixture of MeCOI with 2- or 3-bromotoluene, as well as with 4-bromo-1,2-dimethylbenzene, also led to the formation of polymeric products as a result of polycondensation of aryl iodides formed initially via replacement of bromine by iodine. Irradiation of benzoyl iodide in 2- or 3-bromotoluene involved recombination of benzoyl radicals to give benzil as the only product.     

Vibrational spectra and structure of triphenyltin halides

The solid state IR and Raman spectra of SnPh₃Br do not show any band at 338 cm⁻¹, and there is not C_3ν point group inversion between ν_as SnC₃ and ν_s SnC₃ for SnPh₃X (X  Cl, Br). The presence or absence of a band around 338 cm⁻¹ in the IR spectra of triphenyltin compounds cannot be used to distinguish between pyramidal and planar SnPh₃ groups.     

Mass spectrometry of tropylium halides

The base peak and highest mass number in the spectra of tropylium iodide and bromide corresponds to the mass of the cation. Both appearance potential (AP) measurements and the fragmentation pattern strongly indicate that the gaseous species present is the tropylium radical. Rediction to the corresponding volatile free radical thus takes place prior to evaporation.     

Mild and practical method for the alpha-arylation of nitriles with heteroaryl halides

[reaction: see text] A mild and transition-metal-free method for the alpha-arylation of aliphatic nitriles with activated heteroaryl halides was developed using NaHMDS or KHMDS as base at ambient temperature. The key to the success of this method is generation of the nitrile anion in the presence of the heteroaryl halide. The method is applicable to both primary and secondary carbonitriles and a wide range of heteroaryl halides. Selective monoarylation was observed with primary carbonitriles. The operational simplicity and the mild reaction conditions add to the value of this method as a practical alternative to the preparation of alpha-heteroaryl carbonitriles.     

Bipyridinium ionic liquid-promoted cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides

A new room-temperature ionic liquid has been synthesized from 2,2'-bipyridine. This liquid improved the copper-catalyzed cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides. Good recyclability using this solvent system was observed.