Hydrogen exchange between tert-butyl cation and sulfuric acid

The D/H exchange between tert-butyl-d₉ cation and H₂SO₄ was investigated. The cation participating in the exchange was recovered in the form of p-di-tert-butylbenzene. The mass spectroscopic measurements show a continuous distribution, from zero to nine, of the deuterium atoms in the tert-butyl group originating from the cation.

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D/H --d, H₂SO₄. , , ---. — — - .

     

Interaction between propene and CoNaX zeolite and exchange of propene hydrogens

Interaction of propene with CoNaX and NaX zeolites and exchange of propene hydrogens with CoNaX zeolite was studied at the temperature of the IR beam and at 300°C by means of IR and MS analysis. In addition, the heats of adsorption were measured. The structure of adsorbed propene complexes was found to be influenced by the presence of Co²⁺ ions. The mechanism of the exchange is discussed and the properties of the OH groups of HY, HX and CoNaX zeolites are compared.

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CoNaX NaX CoNaX 300°C . . , Co²⁺ . OH , CoNaX .

     

Equilibria in solutions of methanol or ethanol,sulfuric acid,and alkyl sulfates

Equilibria in reactions of methanol and ethanol with sulfuric acid or in hydrolyses of alkyl sulfates were followed using ¹³C NMR, anion-exchange HPLC, and titrations. Variations of equilibrium constant K = [ester][H₂O]/[ROH][HSO₄^-] with acidity indicate participation of reactions ROH₂⁺ + HSO₄^- ⇌ ROH⁺SO₃^- + H₂O, accompanied by acid base equilibria involving the alcohol and the ester. For mixtures containing initially 20% (w/w) alcohol, pK_MeOH2 + = −4.2, pK_EtOH2+ = −3.7, pK_MeOH+_SO3- = −3.3 and pK_EtOH+_SO3- = −2.7.     

Thallous-thallic exchange reaction in the sulfuric acid solution of some alcohols

The rate constants for thallium(I)-thallium(III) exchange with various alcohols in sulfuric acid solution were determined. In all cases involving alcohols, methanol, ethanol, 2-propanol, 2-methyl-2-propanol, the reaction rates were not accelerated. The larger the formation constants of solvato-complexes for 2-propanol and 2-methyl-2-propanol lead to lower reaction rates in the solution. The mechanism of the exchange reaction was also studied.     

Friedel-crafts reactions of 2-amino-4-(alkyl or aryl)oxazoles with acid chlorides and acid anhydrides: Synthesis of 5-acyl-2-amino-4-alkyloxazoles

Acid chlorides and anhydrides react with 2-amino-4-alkyloxazoles in the presence of aluminum chloride to produce 5-acyl substituted 2-amino-4-alkyloxazoles in modest yields. However, in the absence of the Lewis acid reaction occurs at the amino group to give the corresponding amides. This provides a viable entry for functionalising and making carbon-carbon bond at C-5 of this heterocyclic system.     

Hydrogen evolution and dissolution on smooth ruthenium in sulfuric acid solution

Hydrogen evolution and dissolution were studied under steady-state conditions on smooth ruthenium electrodes in 0.5 M H₂SO₄ at room temperature. Both the anodic current-potential curves, measred under H₂ stirring, and the cathodic curves, measured under N₂ stirring, suggest that the Tafel reaction and convective diffusion are the rate-determining steps at small current densities. At larger cathodic current densities the Volmer reaction becomes predominant. Hydrogen evolution occurs by the Volmer-Tafel mechanism. The coverage with adsorbed hydrogen atoms remains small.     

Polymerization of alkyl vinyl ethers in presence of the sulfuric acid — aluminum sulfate complex

Conclusions In presence of the sulfuric acid — aluminum sulfate complex at 20° stereoregular polymers were prepared from ethyl vinyl, propyl vinyl, isopropyl vinyl, and isobutyl vinyl ethers in yields of 80–90%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 667–670, March, 1967.     

Reactions of alkyl 3-amino-5-aryl-2-benzoyl-5-oxopent-2-enoates with hydrazine

Reactions of alkyl 3-amino-5-aryl-2-benzoyl-2-oxopent-2-enoates with hydrazine were accompanied by debenzoylation and isomerization to give 3-amino-5-aryl-5-oxopent-3-enohydrazides, which underwent cyclization in the presence of an excess of hydrazine into 5(3)-arylpyrazol-3(5)-ylacetohydrazides. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1175–1177, July, 2006.     

Electrophilic substitutions of olefinic hydrogens : Acylation of1,1-bisalkylthio 1,3-alkadienes and trans-n-acetyl-n-isopropyl-1-amino-1,3-butadiene

Reactions of the title compounds with trifluoroacetic anhydride and trichloroacetyl chloride occurred regioselectively to give corresponding 4-triholoacetylated compounds in excellent yields. In contrast, 1,1-bisethylthio-1,3-hexadiene gave preferentially 2-acylated compounds.     

Hydrogen transfer between sulfuric acid and hydroxyl radical in the gas phase: competition among hydrogen atom transfer, proton-coupled electron-transfer, and double proton transfer

In an attempt to assess the potential role of the hydroxyl radical in the atmospheric degradation of sulfuric acid, the hydrogen transfer between H2SO4 and HO* in the gas phase has been investigated by means of DFT and quantum-mechanical electronic-structure calculations, as well as classical transition state theory computations. The first step of the H2SO4 + HO* reaction is the barrierless formation of a prereactive hydrogen-bonded complex (Cr1) lying 8.1 kcal mol(-1) below the sum of the (298 K) enthalpies of the reactants. After forming Cr1, a single hydrogen transfer from H2SO4 to HO* and a degenerate double hydrogen-exchange between H2SO4 and HO* may occur. The single hydrogen transfer, yielding HSO4* and H2O, can take place through three different transition structures, the two lowest energy ones (TS1 and TS2) corresponding to a proton-coupled electron-transfer mechanism, whereas the higher energy one (TS3) is associated with a hydrogen atom transfer mechanism. The double hydrogen-exchange, affording products identical to reactants, takes place through a transition structure (TS4) involving a double proton-transfer mechanism and is predicted to be the dominant pathway. A rate constant of 1.50 x 10(-14) cm(3) molecule(-1) s(-1) at 298 K is obtained for the overall reaction H2SO4 + HO*. The single hydrogen transfer through TS1, TS2, and TS3 contributes to the overall rate constant at 298 K with a 43.4%. It is concluded that the single hydrogen transfer from H2SO4 to HO* yielding HSO4* and H2O might well be a significant sink for gaseous sulfuric acid in the atmosphere.     

Hydrogen exchange of saturated hydrocarbons in homogeneous media Communication 2. Hydrogen exchange of methylcyclohexane in solutions of trifluoroacetic and sulfuric acids at various values of the acidity function

Russian Chemical Bulletin -     

Room-temperature Stille cross-couplings of alkenyltin reagents and functionalized alkyl bromides that possess beta hydrogens

This communication describes a significant expansion in the scope of Stille reactions of Csp3-X electrophiles, specifically, that Pd/P(t-Bu)2Me catalyzes the room-temperature cross-coupling of a variety of functionalized, beta-hydrogen-containing alkyl bromides with an array of alkenyltin reagents. The structure of the phosphine (P(t-Bu)2Me) is well suited for facilitating oxidative addition and avoiding beta-hydride elimination, while the fluoride serves to activate the tin reagent for efficient transmetalation.     

Adamantylazoles: XII. Alkylation of 1-R-tetrazole-5-thiones and 1-R-tetrazol-5-ones with tertiary alcohols in sulfuric acid

In the reaction of 1-(1-adamantyl)-4,5-dihydro-1H-tetrazole-5-thione with 1-adamantyl in sulfuric acid 2-(1-adamantyl)-5-(1-adamantylsulfanyl)-2H-tetrazole and 1,3-bis(1-adamantyl)-5-(1-adamantylsulfanyl)-1H-tetrazolium salt are formed. Methylation of 1-(1-adamantyl)-4,5-dihydro-1H-tetrazole-5-thione in alkaline medium affords 1-(1-adamantyl)-5-methylsulfanyl-1H-tetrazole while its interaction with formaldehyde affoeds 1-(1-adamanttl)-4-(hydroxymethyl)-4,5-dihydro-1H-tetrazole-5-thione.     

Radiation induced exchange reaction between thallium(I) and thallium(III)—Comparison of sulfuric acid and perchiloric acid solution

The rate constant of radiation induced exchange reaction between thallium(I) and thallium(III) ions has been studied for elucidating the mechanisms which are responsible for (T1(II) intermediates or bridging groups (SO ₄ ^2– ) in sulfuric acid and perchloric acid solutions. It was found that the radiation induced exchange reaction is accelerated by the sulfate ion, and the rate of the thallium(II)-thallium(I) reaction is faster than that of the thallium(II)-thallium(III) process in perchloric acid solution.     

Electrosynthesis of 5-amino-4-oxopentanoic acid hydrochloride

The electroreduction of methyl 5-nitro-4-oxopentanate was studied by means of a polarographic method and preparative electrolysis in acidic-alcoholic solutions. The effects of the following factors on the yield and quality of 5-amino-4-oxopentanoic acid hydrochloride were studied: the cathode material, amount of electricity, temperature, nature of the solvent, concentrations of the initial nitro compound and hydrochloric acid, and the cell design. It was shown by electrolysis at a controlled potential and in a galvanostatic mode that the products of methyl 5-nitro-4-oxopentanate electroreduction are hydroxyamino and amino compounds, and also ammonium chloride, nitromethane, methylhydroxylamine hydrochloride, and monomethylamine hydrochloride. Their ratio depends on the electrolysis conditions. The highest overall substance yield (61.1–66.0%) and current yield (68.1–68.6%) of 5-amino-4-oxopentanoic acid hydrochloride was achieved at a copper cathode in a filter-press cell. The content of the main substance in the electrochemically obtained samples of 5-amino-4-oxopentanoic acid was 89.5–91.0%.     

Formation and Oxidation of Hydrogen Molybdenum Bronze on Platinum Electrode in Sulfuric Acid Solution

Hydrogen molybdenum bronze (HxMoO3) can be electrodeposited on platinum and oxidized in two steps to the hydrogen molybdenum bronze with less amount of hydrogen HyMoO3 (y相似文献   

Selective acid hydrolysis of 2-substituted-5-dimethylaminomethyleneaminopyrimidines to 5-amino- and 5-hydroxypyrimidines

Conditions are described for the selective acid hydrolysis of 2-substituted-5-dimethylaminomethyleneaminopyrimidines in 0.2–2 M sulfuric acid, to give high yields of the corresponding 5-amino- and difficultly accessible 5-hydroxypyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 801–803, June, 1990.