Kinetics of oxidation of 2,2,4,5,5-pentamethyl-1-hydroxy-3-imidazoline-3-oxide by decanepersulfonic acid

The kinetics was studied of the oxidation of 2,2,4,5,5-pentamethyl-1-hydroxy-3-imidazoline-3-oxide by decanepersulfonic acid in a chloroform solution. The corresponding nitroxyl radical is quantitatively formed by the reaction 2=N-OH + RSO₄H 2=NO + RSO₃H + H₂O A mechanism of the reaction was proposed and the rate constant of the limiting stage of the process was determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1265–1268, June, 1990.     

The synthesis of metal–organic framework Al‐MIL‐53‐derived Brønsted acid catalyst and its application in the Mannich reaction

A metal–organic framework Al‐MIL‐53‐NH₂‐derived Brønsted acid catalyst (Al‐MIL‐53‐RSO₃H) has been synthesized employing a post‐synthetic modification strategy under mild conditions. The Al‐MIL‐53‐RSO₃H catalyst was successfully utilized in the nitro‐Mannich reaction taking advantage of its strong Brønsted acidity. Good to excellent yields of Mannich adducts were achieved for a variety of acylimine substrates in the presence of 0.1 mol% Al‐MIL‐53‐RSO₃H. Furthermore, the Al‐MIL‐53‐RSO₃H catalyst can be recycled five times without decreasing the yield and selectivity of Mannich adducts.     

The kinetics of acid-catalyzed decomposition of decanepersulfonic acid

The kinetics of thermal decomposition of decanepersulfonic acid (RSO₂OOH, R=C₁₀H₂₁) in CCl₄ in the presence of cyclohexanesulfonic and trifluoroacetic acids at 323–343 K was studied. The reaction has an autocatalytic character. The kinetics of consumption of the persulfonic acid is described by the equation-d[RSO₂OOH]/dt=k ₁[RSO₂OOH]+k ₂[RSO₂OOH]·[HX]. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 202–203, January, 1999.     

Mass spectra of sulfinamide derivatives and identification of their thermal decomposition products

The mass spectra of 30 sulfinamide derivatives (RSONHR', R' alkyl or p-XC₆H₄) are reported. Most of the spectra had peaks attributable to thermal decomposition products. For some compounds these were identified by pyrolysis under similar conditions to be: RSO₂NHR', RSO₂SR, RSSR and NH₂R' (in all kinds of sulfinyl amides); RSNHR' (in the case of arylsulfinyl arylamides); RSO₂C₆H₄NH₂, RSOC₆H₄NH₂ and RSC₆H₄NH₂ (in the case of arylsulfinyl arylamides of the type of X = H) The mass spectra of the three thermally stable compounds showed that there are several kinds of common fragment ions. The mass spectra of the thermally labile compounds had two groups of ions; (i) characteristic fragment ions of the intact molecules and (ii) the molecular ions of the thermal decomposition products. It was concluded that the sulfinamides give the following ions after electron impact: [M]⁺, [M ? R]⁺, [M ? R + H]⁺, [M ? SO]⁺, [RS]⁺, [NHR']⁺, [NHR' + H]⁺, [RSO]⁺, [RSO + H]⁺, [R]⁺, [R + H]⁺, [R']⁺ and [M ? OH]⁺, and that the thermal decomposition products give the following ions: [RSO₂SR]⁺, [RSSR]⁺, [M ? O]⁺, [M + O]⁺ and [RSOC₆H₄NH₂]⁺.     

Analysis of sodium alkylsulphonates using filament heated in-beam electron impact mass spectrometry

Summary By means of the filament heated in-beam method at 280–450° C, the series of sodium alkylsulphonates (RSO₃Na, where R=C₂H₅ to n-C₁₂H₂₅) give very simple mass spectra: Na⁺, [RSO₃Na₂]⁺, which is the base peak except for R=n-C₄H₉, [(RSO₃)₂Na₃]⁺ and, in most cases, [(RSO₃)₃Na₄]⁺. Fragmentations other than these three or four peaks are observed only in the case of n-heptylsulphonate. The proposed method of analysis for simple alkylsulphonic acids is applicable to ordinary electron-impact mass spectrometers.

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Analyse von Natrium-alkylsulfonaten durch Elektronenstoß-Massenspektrometrie mit Probenerhitzung im Elektronenstrahl

Zusammenfassung Mit Hilfe dieser Methode (280–450° C) erhält man für Natriumalkylsulfonate (RSO₃Na mit R=C₂H₅ bis n-C₁₂H₂₅) sehr einfache Massenspektren: Na⁺, [RSO₃Na₂]⁺ (Basispeak mit Ausnahme von R=n-C₄H₉), [(RSO₃)₂Na₃]⁺ und in den meisten Fällen [(RSO₃)₃Na₄]⁺. Andere Fragmentierungen als diese 3 oder 4 Peaks wurden nur bei n-Heptylsulfonat beobachtet. Dieses Verfahren zur Analyse einfacher Alkylsulfonsäuren ist für übliche Elektronenstoß-Massenspektrometer verwendbar.

     

The electrophilic addition of thiols to olefins: A theoretical and experimental study

Density functional theory with the B3LYP hybrid functional and 6–31G* basis set was used to study the geometric and electronic structure of H₂C = CHR (R = H, CH₃, C₂H₅, C₃H₇, C₄H₉, and C₅H₁₁) olefins, their carbocations formed in the addition of the proton to the olefins, R′-S-H aliphatic thiols (R′ = H, CH₃, C₂H₅, and C₃H₇), the products of the addition of thiols to carbocations, and the final products of the addition of thiols to olefins. The proton affinity of the olefins and the products of the addition of thiols to olefins was calculated. The conclusion was drawn that the limiting stage in the nonradical addition of thiols to olefins catalyzed by acids was proton transfer from the protonated reaction product to the olefin. The theoretical results were compared with the experimental data on the electrophilic addition of polymercaptan to heptene-1.     

Difluoromethylation of Sulfonamides

Reactions of sulfonamides RSO₂NHR' with chlorodifluoromethane and solid alkali give the corresponding derivatives RSO₂N(CHF₂)R' containing a difluoromethyl group on the nitrogen atom. Sulfonamides derived from 2-aminobenzothiazole and 2- and 4-aminopyridines react with chlorodifluoromethane at the endocyclic nitrogen atom.     

Carbonylation of Tertiary Alkyl Halides Synthesis of Pivaloyl Halides

The carbonylation of tert-butyl halides in a two-phase system, RSO₃H/CCl₄, under carbon monoxide pressure affords the corresponding pivaloyl halides in good yields and selectivities.     

Polymerization and reaction of tetraoxane with various olefins catalyzed by BF3O·(C2H5)2

The copolymerization of tetraoxane with various olefins by BF₃·O(C₂H₅)₂ in ethylene dichloride at 30°C has been studied. The gas chromatographic technique was employed for the determination of concentration of each compound. The rate of tetraoxane consumption was decreased by the addition of olefins in the order of; no addition > trans-stilbene > styrene > 1,1-diphenylethylene > 2-chloroethyl vinyl ether > cyclohexene ≥ indene ≥ α-methylstyrene. The formation of the methanol-insoluble copolymer of tetraoxane and olefin was not confirmed. However, 4-methyl-4-phenyl-1,3-dioxane and 4,4-diphenyl-1,3-dioxane were formed in the reaction of tetraoxane with α-methylstyrene and 1,1-diphenylethylene, respectively. 4,4-Diphenyl-1,3-dioxane was identified on the basis of the molecular weight measurement, elemental analysis and NMR and infrared spectroscopy. On the other hand, 1,3-dioxane derivatives were not formed in the reaction of tetraoxane with α,β-disubstituted olefins. Monomer composition dependence of the copolymerization of tetraoxane with 1,1-diphenylethylene or α-methylstyrene has been studied. The amount of 4,4-diphenyl-1,3-dioxane formed reached a maximum at a monomer composition of 1:1 in the reaction of tetraoxane with 1,1-diphenylethylene. The formation of cyclic dimer of α-methylstyrene was suppressed by tetraoxane.     

Thermal and photochemical olefin isomerizations with complex [(C5Me4H)2Ti(CH3)2] as initiator

Irradiation of the complex [(C₅Me₄H)₂Ti(Ci(CH₃)₂] in an olefin as a solvent promotes stereospecific photoassisted isomerizations: olefins with terminal double bonds are rapidly isomerized into 2-alkenes with an E-configuration. Kinetic studies of hydrogen migration and of Z-E isomerizations of disubstituted olefins have demonstrated the influence of substitution and of branching of the hydrocarbon chain on the course of the reaction. Formation of paramagnetic complexes of Ti^III that are probably intermediates in these reactions has been confirmed by ESR. The same reactions, but with a lower stereoselectivity, are initiated thermally by the [(C₅Me₄H)₂Ti(CH₃)₂] complex.     

Copper‐Catalyzed Trifluoromethylation of Internal Olefinic CH Bonds: Efficient Routes to Trifluoromethylated Tetrasubstituted Olefins and N‐Heterocycles

The functionalization of internal olefins has been a challenging task in organic synthesis. Efficient Cu^II‐catalyzed trifluoromethylation of internal olefins, that is, α‐oxoketene dithioacetals, has been achieved by using Cu(OH)₂ as a catalyst and TMSCF₃ as a trifluoromethylating reagent. The push–pull effect from the polarized olefin substrates facilitates the internal olefinic C?H trifluoromethylation. Cyclic and acyclic dithioalkyl α‐oxoketene acetals were used as the substrates and various substituents were tolerated. The internal olefinic C?H bond cleavage was not involved in the rate‐determining step, and a mechanism that involves radicals is proposed based on a TEMPO‐quenching experiment of the trifluoromethylation reaction. Further derivatization of the resultant CF₃ olefins led to multifunctionalized tetrasubstituted CF₃ olefins and trifluoromethylated N‐heterocycles.     

Systematische untersuchungen über das verhalten von organozinnverbindungen gegenüber flüssigem schwefeldioxid III. SO2-disproportionierung bei einschiebungsreaktionen an tetraalkylstannanen

When liquid SO₂ is allowed to react with the tetraalkyltin compounds (CH₃)₄Sn and (C₂H₅)₄Sn at 60°, disproportionation of sulfur takes place resulting in the formation of the corresponding bis(trialyltin) sulfates, [R₃Sn]₂SO₄, and alkanethiosulfonic acid S-alkyl esters, RSO₂SR (R = CH₃, C₂H₅). The course of the reaction is discussed.     

Fragmentation in cationic olefin oligomerization

The dominant products from the polymerization of butene-2 in CH₂Cl₂ at ?25°C with BF₃CH₃OH as catalyst are C₁₀, C₁₂, and C₁₄ olefins. Formed in lesser amounts are C₉ and C₁₃ olefins but C₅–₇ and C₁₁ olefins have not been detected. The few products so far identified retain the basic butene-2 structure suggesting that the anomalous products may not be formed in a typical carbonium-ion-type rearrangement reaction but perhaps arise in a fission process associated with the propagation and/or transfer steps in the polymerization. With propylene as monomer the normal oligomers are by far the most important products, but all fission products can be detected.     

Synthesis of monohalocyclopropane derivatives from olefins by the reaction with trihalomethanes and copper

Fluoro-, chloro-, bromo-, and iodocyclopropane derivatives were obtained in 10–80% yields by the reaction of FCHI₂, ClCHI₂, BrCHI₂, and CHI₃, respectively, with Cu in the presence of olefins. The reaction was electrophilic, and proceeded stereospecifically, i.e., cis and trans olefins afforded cyclopropane derivatives whose configurations with respect to the substituents from original olefins were cis and trans, respectively. Since isomeric olefins were not detected in the reaction mixture which would be expected from the insertion of the corresponding free monohalocarbenes into C—H bonds, the reaction seemed to proceed via organocopper intermediates rather than free monohalocarbenes. With respect to the configuration of the halogen introduced by the new reaction, the cis or endo isomers were generally obtained predominantly over the corresponding trans or exo isomers.     

Nouvelle methode de synthese de tetrahydro-2,3,4,5 benzo (b) 1H-azepines substituees en position -2

Treatment of tertiary alcohols and trisubstituted olefins of the tetrahydronaphthalene series with the HN₃H₂SO₄ reagent leads directly and with good yields to a new class of compounds: the 3,4-dihydro 5H benzo (b) azepins substituted on position -2. The latter, on reduction, give the corresponding 2,3,4,5-tetrahydro 1H benzo (b) azepins, most of them being unknown in the literature. This work shows the high regiospecificity of this ring expansion reaction which can be explained by electronic and steric effects.     

Peracid dependent stereoselectivity and functional group contribution to the stereocontrol of epoxidation of (E)-alkene dipeptide isosteres

Twelve Boc-protected phenylalanyl-phenylalanine and phenylalanyl-glycine trans-vinyl isosteres were epoxidised with magnesium monoperoxyphtalate hexahydrate (MMPP) and trifluoroperacetic acid, and the results have been compared with those from earlier studies on epoxidations with m-CPBA. The alkenes were synthesised in high yields with high E/Z-selectivities using either the Julia or Schlosser reactions. The formation of threo isomers was favoured in all epoxidation reactions except with CF₃CO₃H on substrates containing two allylic/homoallylic functional groups directing the peracid to opposite faces of the alkene. The switch to erythro selectivity observed with CF₃CO₃H is suggested to emanate from coordination to the allylic ester functionalities via hydrogen bond donation from the peracid. The other peracid reagents seem to be preferentially coordinated to the allylic carbamate function. The contribution of individual functional groups to the stereopreference was also investigated.     

Transition metal-catalyzed olefin arylation via C–H bond activation of arenes

In this article, two kinds of our transition metal-catalyzed olefin arylations are summarized and discussed. The first one is Ir-catalyzed novel anti-Markovnikov hydroarylation of olefins with benzene. Using this reaction catalyzed by [Ir(μ-acac-O,O′,C₃)(acac-O,O′)(acac-C₃)]₂ (acac = acetylacetonato), 1, straight-chain alkylarenes, which were not obtainable by the conventional Friedel-Crafts aromatic alkylation with olefins, were able to be successfully synthesized directly from arenes and olefins with the higher selectivity than that of branched alkylarenes. This is the first efficient catalyst which shows the desirable high regioselectivity. The reaction of benzene with propylene gave n-propylbenzene and cumene in 61% and 39% selectivities, respectively, and the reaction of benzene and styrene afforded 1,2-diphenylethane in 98% selectivity. The reaction of alkylarene and olefin showed meta and para orientations. A wide range of olefins and arenes can be employed for the synthesis of alkylarenes. The mechanism of the reaction involves C–H bond activation of benzene by Ir center to form Ir–phenyl species. The second reaction is Rh-catalyzed oxidative arylation of ethylene with benzene to directly produce styrene, namely one-step synthesis of styrene. The reaction of benzene with ethylene catalyzed by Rh(ppy)₂(OAc) (ppyH = 2-phenylpyridine, OAc = acetate), 3 with Cu oxidizing agent gave styrene and vinyl acetate in 77% and 23% selectivities, respectively, in contrast to those by Pd(OAc)₂, 47% of styrene and 53% of vinyl acetate. The mechanism of the reaction involves Rh-mediated C–H bond activation of benzene, which appears to be a rate-determining step. Furthermore, Rh complexes in a Rh(I) oxidation state at the beginning of the reaction work as catalysts for the reaction by addition of acacH and O₂ without any oxidizing agent, like Cu salt.     

A Rapid and Simple Method for Quantitative Aziridination from Aminobrominated Derivatives of Olefins under Solvent‐free and Mild Conditions

The urea‐catalyzed aziridination of 1,2‐vicinal haloamines derived from aminohalogenation of olefins has been developed. This rapid and simple method was carried out by simply grinding the solid mixture of the substrate, K₂CO₃ and catalytic amount of urea at room temperature in air. The reaction provides a protocol for quantitative preparation of aziridines in a large scope of aminohalogenated derivatives of olefins including α,β‐unsaturated ketones, α,β‐unsaturated esters and simple olefins. The possible mechanism involving an H‐bond promoting deprotonation has been suggested for this reaction.     

Über organogermaniumtrisulfinsäureester und versuche zur darstellung von tetrasulfinsäureestern des germaniums

The trisulfinic esters of germanium RGe(O₂SR′)₃ (R = R′ = CH₃; R = C₆H₅, R′ = CH₃, C₂H₅), which are sensitive to hydrolysis and temperature, are obtained by reaction of the corresponding trichlorides RGeCl₃ with anhydrous silver sulfinates. Aromatic trisulfinic esters as well as tetrasulfinic esters of germanium could not be obtained because of steric reasons. The esters, in which the RSO₂^?-residues are linked to germanium via oxygen, are investigated on the basis of their ¹H NMR, mass, IR and Raman spectra.     

Pseudoelementverbindungen. IV. Modifizierung der Ionen Sulfit [SOY2]2−, Sulfat [SO4−nYn]2− und Sulfonat [RSO2Y]− durch Einführung der Pseudochalkogengruppen NCN und C(CN)2

Pseudoelement Compounds. IV. Modification of the Ions Sulfite [SO₂Y]^2?, Sulfate [SO_4?nY_n]^2?, and Sulfonate [RSO₂Y]^? by Introducing Pseudochalcogen Groups NCN and C(CN)₂ . Described is the synthesis of pseudochalcogen modified sulfites M₂[SOY₂], sulfates M₂[SO_4?nY_n] (Y = NCN), and arylsulfonates M[RSO₂Y] (Y = NCN, C(CN)₂). The ¹³C-NMR and IR spectra of the new compounds are discussed.