Synthesis of cyclic sulfides

2-n-Amyl-5-methylthiacyclopentane and 2-n-amylthiacyclohexane, respectively, were synthesized by the reaction of 1-heptene episulfide with allylmagnesium bromide with subsequent cyclization of the resulting 1-decene-5-thiol by the action of 75% sulfuric acid and UV irradiation.See [3] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1337–1338, October, 1971.     

Synthesis of cyclic sulfides

A general scheme is proposed for the synthesis of 4-alkylthiacyclohexanes by reaction of 1-alken-3-ylmagnesium halides with ethylene episulfide and subsequent cyclization of the resulting 3-alkylpent-4-ene-1-thiols under the in-fluence of UV irradiation. 4-Amyl- and 4-octylthiacyclohexanes, together with 2-methyl-3-octylthiacyclopentane, were obtained, respectively, from 1-octen-3-ylmagnesium bromide, 1-undecen-3-ylmagnesium chloride, and ethylene episulfide.See [1] for communication. VII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1622–1624, December, 1977.     

Synthesis of cyclic sulfides

3-Phenylthiacyclohexane and 2-methyl-4-phenylthiacyclopentane were synthesized by reaction of styrene episulfide with allylmagnesium bromide and subsequent photochemical cyclization of the resulting 2-phenyl-4-pentene-1-thiol.     

Reactivity of quinones as alkyl radical acceptors

The enthalpies of the addition of 11 alkyl radicals to ortho-and para-benzoquinones and substituted para-benzoquinones and the enthalpies of formation of various alkoxyphenoxyl radicals have been calculated. Experimental data for the addition of alkyl radicals to quinones are analyzed in terms of the intersection of two parabolic potential curves, and parameters characterizing this class of reactions are calculated. The classical potential barrier of the thermally neutral reaction of alkyl radical addition to benzoquinone is E _e,0 = 82.1 kJ/mol. This class of reactions is compared to other classes of free-radical addition reactions. The interaction between the electrons of the reaction center and the π electrons of the aromatic ring is a significant factor in the activation energy. Activation energies, rate constants, and the geometric parameters of the transition state have been calculated for 40 reactions of alkyl radical addition to quinones. Strong polar interaction has been revealed in the addition of polar macroradicals to quinones, and its contribution to the activation energy has been estimated. Kinetic parameters, activation energies, and rate constants have been calculated for the reverse reactions of alkoxyphenoxyl radical decomposition to quinone and alkyl. The competition between chain termination and propagation reactions in alkoxyphenol-inhibited hydrocarbon oxidation is discussed.     

Synthesis of cyclic sulfides

2,8-Dimethyl-1-thiahydrindan and 9-methyl-1-thiadecalin, respectively, were obtained by the reaction of 1-methyl-1-cyclohexene episulfide with allylmagnesium bromide and subsequent intramolecular cyclization of the resulting 1-methyl-2-allylcyclohexane-1-thiol by the action of sulfuric acid or UV irradiation. The cyclization proceeds stereospecifically.See [1] for communication V.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1186–1188, September, 1972.     

Synthesis of cyclic sulfides

Two isomers of 2,3-dimethyl-1-thiahydrindane and two isomers of 4-methyl-1-thiadecali were obtained by the reaction of cyclohexene episulfide with crotylmagnesium bromide and subsequent cyclization of the resulting 2-(-methyl--propenyl)-1-cyclohexanethiol by the action of 75% sulfuric acid and UV irradiation.See [3] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 622–625, May, 1972.     

Synthesis of cyclic sulfides

A new method for the synthesis of bicyclic sulfides consisting of the reaction of cycloolefin sulfides with vinylmagnesium or allylmagnesium bromides and the subsequent intramolecular cyclization of the resulting unsaturated mercaptans has been proposed. By using this method, from cyclohexene sulfide we have synthesized 1-thiadecalin and 2-methyl-1-thiahydrindan; and complexes of these substances with mercuric chloride, and their methiodides and sulfones have been obtained.The results of this work were reported in part at the XI-th Scientific Meeting on the Chemistry of Organosulfur Compounds of Petroleum and Petroleum Products (Ufa, 1968).     

Polymerization of cyclic sulfides

The ring-opening polymerizations of cyclic sulfides containing three-, four-, and fivemembered rings were studied. In conjunction with these polymerizations, the relative basicities of the cyclic sulfides employed were also investigated. Polymerizations were effected by the use of phosphorus pentafluoride, boron trifluoride ethyl ether, triethylaluminum, and trimethyloxonium tetrafluoroborate. The resulting polymers were oxidized to the sulfones and differential thermal analyses were obtained on the sulfide polymers as well as the sulfone analogs.     

Synthesis of cyclic sulfides

2-Methyl-, 2,5-dimethyl-, 2-n-butyl-5-methylthiacyclopentanes, thiacyclohexane, and 2-methyl- and 2-n-butylthiacyclohexanes were obtained by the reaction of ethylene, propene, and 1-hexane episulfides with allylmagneisum bromide with subsequent cyclization of the alkenethiols thus formed.See [2] for Communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1614–1616, December, 1970.     

The effect of pressure on hydrogen transfer reactions with quinones

The effect of pressure on the oxidation of hydroarenes 3-9 with 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ; 1 a) or o-chloranil (10), leading to the corresponding arenes, has been investigated. The activation volumes were determined from the pressure dependence of the rate constants of these reactions monitored by on-line UV/Vis spectroscopic measurements in an optical high-pressure cell (up to 3500 bar). The finding that they are highly negative and only moderately dependent on the solvent polarity (DeltaV( not equal ) = -13 to -25 in MTBE and -15 to -29 cm(3) mol(-1) in MeCN/AcOEt, 1:1) rules out the formation of ionic species in the rate-determining step and is good evidence for a hydrogen atom transfer mechanism leading to a pair of radicals in the rate-determining step, as was also suggested by kinetic measurements, studies of kinetic isotope effects, and spin-trapping experiments. The strong pressure dependence of the kinetic deuterium isotope effect for the reaction of 9,10-dihydroanthracene 5/5-9,9,10,10-D(4) with DDQ (1 a) can be attributed to a tunneling component in the hydrogen transfer. In the case of formal 1,3-dienes and enes possessing two vicinal C--H bonds, which have to be cleaved during the dehydrogenation, a pericyclic hydrogen transfer has to considered as one mechanistic alternative. The comparison of the kinetic deuterium isotope effects determined for the oxidation of tetralin 9/9-1,1,4,4-D(4)/9-2,2,3,3-D(4)/9-D(12) either with DDQ (1 a) or with thymoquinone 1 c indicates that the reaction with DDQ (1 a) proceeds in a stepwise manner through hydrogen atom transfer, analogously to the oxidations of 1,4-dihydroarenes, whereas the reaction with thymoquinone 1 c is concerted, following the course of a pericyclic hydrogen transfer. The difference in the mechanistic courses of these two reactions may be explained by the effect of the CN and Cl substituents in 1 a, which stabilize a radical intermediate better than the alkyl groups in 1 c. The mechanistic conclusions are substantiated by DFT calculations.     

Hydride shift reactions with the participation of two-ring sulfides

2,3-Dihydrobenzothiophenes are dehydrogenated to the corresponding benzothiophenes on reaction with the hydride-ion acceptors triphenylmethyl tetrafluoroborate and chloranil. Thiochroman reacts with chloranil to give 2-methyl-2,3-dihydrobenzothiophene and 2-methylbenzothiophene and reacts with triphenylmethyl tetrafluoroborate to give a thiochromenylium salt.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 328–330, March, 1976.     

Reactivity of alkylperoxyl radicals in reactions with aromatic nitrons

Interaction of tetradecylperoxyl radicals with two aromatic nitrons has been studied.

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Photolysis of diazocyclopentadiene : Reactivity of cyclopentadienylidene in sulfides and ethers

Photolysis of diazocyclopentadiene in the presence of dimethyl, diethyl and tetramethylene sulfides gave the corresponding sulfonium cyclopentadienylide. But the ylides from diisopropyl and di-t-butyl sulfides were unstable, and the reaction mixture gave the CH and CS insertion products of cyclopentadienylidene and olefin elimination products. Reaction of diazocyclopentadiene in ethers gave the CH insertion and some CO insertion products. For diethyl ether, the insertion ratio into secondary and primary CH bonds was 19:1. For tetrahydrofuran, both α and β-CH insertion products were observed in ratio of 3:0. Photolysis of diazocyclopentadiene in allylic ethers gave the addition product of the carbene to the double bond, but in allylic sulfides gave both CS insertion and addition products of the carbene.     

Reactivity of nitrovinylquinones with cyclic and acyclic enol ethers

The nitrovinyl-substituted quinones 2-(2-nitrovinyl)-1,4-benzoquinone and 2-(2-nitrovinyl)-1,4-naphthoquinone react with a variety of cyclic and acyclic enol ethers via two competing pathways. In one pathway, the nitrovinylquinone acts as an inverse electron-demand [4 + 2] diene. This gives quinoid carbocycles, which readily tautomerize to their hydroquinone form. The other pathway involves conjugate (Michael) addition of the enol ether to the nitrovinylquinone, followed by ring closure. This gave dihydrobenzofurans, which can eliminate an alcohol to give benzofurans. Hindered enol ethers tended to favor the conjugate addition pathway, while less hindered enol ethers favored cycloaddition.     

Reactivity of haloalkanes in their reactions with the chlorine atom

Experimental kinetic data on reactions of the chlorine atom with halogenated derivatives of methane and ethane (37 reactions) have been analyzed by the intersecting-parabolas method. The following five factors have an effect on the activation energy of these reactions: the enthalpy of reaction, triplet repulsion, the electronegativities of the reaction center atoms, the dipole–dipole and multidipole interactions between the reaction center and polar groups, and the effect of π electrons in the vicinity of the reaction center. The increments characterizing the contribution from each factor to the activation energy of the reaction have been calculated. The contribution from the polar interaction, ΔE _μ, to the activation energy depends on the dipole moment of the polar group and obeys the following empirical equation: ln(Δ_{E μ}/Σμ) = ?0.74 + 0.87(ΔE _μ/Σμ) ? 0.084(ΔE _μ/Σμ)².     

Photoinduced electron transfer reactions of pyrylium derivatives with organic sulfides in acetonitrile

The photochemistry and photophysics of pyrylium derivatives with organic sulfides in acetonitrile medium are investigated. A steady decrease in the fluorescence intensity and fluorescence lifetime of the dyes was observed with increase in the quencher concentration. Bimolecular quenching constants were evaluated and correlated with the free energy of electron transfer. Laser flash photolysis investigations on the dyes in presence of quenchers were done. Observation of pyranyl radical and sulfide cation radicals as intermediates clearly illustrates the electron transfer mechanistic pathway for this reaction. The radical pair energies were calculated and found to be lower than the triplet energy of the sensitisers and hence we do not see any triplet induction in the present system.