- Synthesis of Asymmetrical Sulfide Compounds and Asymmetrical Ether Compounds
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The present invention discloses methods for synthesizing asymmetrical sulfide compounds and asymmetrical ether compounds from a variety of ether, sulfide, alcohol, and thiol reactants that are contacted in the presence of a suitable catalyst. Conversions of the limiting reactant to the desired asymmetrical sulfide or asymmetrical ether compound generally exceed 50%.
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Paragraph 0108-0112
(2019/09/15)
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- Catalytic synthesis of dialkyl sulfides from dialkyl disulfides
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Dialkyl disulfides R2S2 where R = Me, Et, or Pr, both as individual compounds and as their mixtures, isolated from petroleum products can turn into alkanethiols and dialkyl sulfides under the action of catalysts having strong acid sites and medium-strength basic sites on their surface. In a helium atmosphere, the main conversion products are alkanethiols, while dialkyl sulfides form in low yield at a selectivity of no higher than 20%. A much higher dialkyl sulfide selectivity is attained in the reaction involving methanol. The most efficient catalyst for this reaction is alumina, with which the dialkyl sulfide selectivity is up to 99%.
- Mashkina,Khairulina
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p. 402 - 408
(2017/08/08)
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- Semi-continuous photochemical method and device therefor
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In the photochemical synthetic process in semi-continuous mode according to the invention, a reactor comprising two zones is used, the radiating portion of the lamp(s) being totally immersed in a first zone which is completely filled with reaction medium and spills off via an overflow into a second zone whose volume is sufficient to contain the volume of reaction medium originating from the first zone and corresponding substantially to the volume of the reagent(s) gradually introduced.
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Page/Page column 2
(2008/06/13)
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- Inactivation of mitochondrial monoamine oxidase B by methylthio-substituted benzylamines
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Mitochondrial monoamine oxidase was inactivated by o-mercaptobenzylamine (1) and o- (2) and p-methylthiobenzylamine (5). Experiments were carried out to provide evidence for possible mechanisms of inactivation. The corresponding o- (3) and p-hydroxybenzylamine (4) are not inactivators. Four radiolabeled analogues of 2 and 5, having radioactivity at either the methyl or benzyl groups, were synthesized, and all were shown to incorporate multiple equivalents of radioactivity into the enzyme. Inactivation in the presence of an electrophile scavenger decreased the number of molecules incorporated, but still multiple molecules became incorporated; catalase did not further reduce the number of inactivator molecules bound. Two inactivation mechanisms are proposed, one involving a nucleophilic aromatic substitution (SNAr) mechanism and the other a dealkylation mechanism. Evidence for both mechanisms is that inactivation leads to reduction of the flavin (oxidation of the inactivator), but upon denaturation the flavin is reoxidized, indicating that attachment is not at the flavin. A cysteine titration indicates the loss of four cysteines after inactivation and denaturation. Support for the S NAr mechanism was obtained by showing that o- and p-chlorobenzylamine also inactivate MAO. Chemical model studies were carried out that also support both SNAr and dealkylation mechanisms.
- Lu, Xingliang,Rodriguez, Maria,Gu, Wenxin,Silverman, Richard B.
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p. 4423 - 4430
(2007/10/03)
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- Thermal degradation processes in polysulphide polymers investigated by flash pyrolysis gas chromatography/mass spectrometry
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Thermal degradation of four polysulphides, poly(methylenesulphide), poly(methylenedisulphide), poly(methylenetetrasulphide), and poly(styrenesulphide)-co-poly(methylenesulphide) have been investigated by pyrolysis gas chromatography/mass spectrometry technique (Py-GC/MS). The pyrolysis products detected by Py-GC/MS indicate that the thermal decomposition of these polymers yields cyclic sulphides by an intramolecular exchange process. The linear products with thiol end groups also form along with the cyclic products through a β-CH hydrogen transfer reaction.
- Sundarrajan, Subramanian,Ganesh, Kannan,Kishore, Kaushal,Surianarayanan, Mahadevan
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p. 491 - 496
(2007/10/03)
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- Synthesis of organophosphorus compounds in terms of elemental phosphorus, sulfur and their derivatives
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We have developed new facile methods for synthesizing various organophosphorus compouds on the basis of elemental phosphorus and sulfur, phosphorus sulfides and esters of thiophosphorous acids.
- Batyeva, Elvira S.,Nizamov, Il'yas S.,Kursheva, Lidiya I.,Frolova, Liliya V.
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- Alkylation of thiols using KOH in dimethyl sulphoxide
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Aliphatic, aromatic and heteroaromatic thiols have been conveniently alkylated to the thioethers in good yield using solid KOH in DMSO.
- Goswami, Birendra N,Rastogi, Romesh C
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p. 703 - 704
(2007/10/02)
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- Electronic and steric effects in the dissociative displacement of thioethers from mixed phenyl(thioether)platinum(II) complexes
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A series of compounds of the type cis-[PtPh2L2], where L encompasses a wide range of thioethers of different steric and electron-donating characteristics, have been prepared and characterized. Most of these monomeric compounds exist in solution in equilibrium with the sulfur-bridged dimer [Pt2Ph4(μ-L)2] and the free thioether. Addition of small amounts of ligand in solution allows the stabilization of the monomeric form. Kinetic studies of the displacement of the thioethers with 2,2′-bipyridine (bpy) to yield [PtPh2(bpy)] in CH2Cl2 at 298.16 K, carried out in the presence of sufficient excess of [L] and [bpy] to ensure pseudo-first-order conditions, showed that the reactions follow a bivariate nonlinear rate law kobsd = a[bpy]/(b[L] + [bpy]) + c[bpy], which has the same form as that of similar systems for which a dissociative mechanism has been proposed. The reactivity decreases linearly with increasing σ-donor ability of the leaving thioether, with bulky substituents on sulfur playing an accelerating role. The relative sensitivities of the dissociative and associative processes to the inductive effects of the leaving group are compared and related to the degree of lengthening and weakening of the bond with the metal produced by the trans-activating group.
- Alibrandi, Giuseppe,Minniti, Domenico,Scolaro, Luigi Monsù,Romeo, Raffaello
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p. 1939 - 1943
(2008/10/08)
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- Trimethylphosphine: Anion-Molecule Reactions and Acidity in the Gas Phase
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Gas-phase acidity of trimethylphosphine has been investigated at ambient temperature by examining proton-transfer reactions in 40 Pa of helium buffer gas in a Flowing Afterglow instrument.On the basis of the occurence-non-occurence of a number of proton-transfer reactions and the observation of rapid H-D exchange between D2O and the conjugate base of trimethylphosphine, it has been determined that trimethylphosphine is more acidic than water.Quantitative measurements are reported for the reaction of trimethylphosphine with atomic oxygen anion and methoxide.These latter two anions exhibit multiple reaction pathways, one of which is proton transfer.From measurements of the rate coefficients of these two reactions and the relative product yields, it is concluded that the gas-phase acidity of trimethylphosphine is very similar to that of the hydroxyl radical; the recommended value is ΔGoacid(PMe3) 1577 +/- 13kJ mol-1.The derived acidity measurement is in slight contrast to recent theoretical and experimental estimates.Furthermore, it is found that anions which react only slowly with trimethylphosphine by proton transfer can undergo an alternative reaction which corresponds to addition of the neucleophilic anion to trimethylphosphine followed by loss of methane.
- Grabowski, Joseph J.,Roy, Paul D.,Leone, Robert
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p. 1627 - 1632
(2007/10/02)
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- REACTION OF THIOACETALS WITH TRIETHYLSILANE IN THE PRESENCE OF LEWIS ACIDS AND REDUCED NICKEL
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1,1-Di(alkylthio)alkanes, 1,3-oxathiolanes, 1,3-dithiolanes, and ortho thioesters are cleaved by triethylsilane in the presence of catalytic amounts of zinc iodide or reduced nickel.In the presence of zinc iodide the acyclic dithioacetals and ortho thioester are converted into alkyl sulfides and triethyl(alkylthio)silanes by cleavage of the carbon-sulfur bond.The analogs of the cyclic acetals are cleaved by triethylsilane only in the presence of reduced nickel, while regiospecific cleavage of the heterocycle at the carbon-oxygen bond is observed in 1,3-oxathiolanes.The cleavage of the 1,3-dithiolanes takes place by a more complicated mechanism with the formation of the disilyl ether of ethanediol, hexaethyldisilylthiane, and triethyl(alkylthio)silanes.The cyclic ortho thioester reacts with triethylsilane both at zinc iodide and at reduced nickel with the formation of the products from preferential cleavage of the exocyclic bond.
- Kirilyuk, B. A.,Mel'nitskii, I. A.,Golub, N. M.,Kiladze, T. K.,Kantor, E. A.,Rakhmankulov, D. L.
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p. 1754 - 1758
(2007/10/02)
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- The vibrational spectra and rotational isomerism of methyl ethyl sulphone-d0, -d3 and -d5
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The infrared and Raman spectra of methyl ethyl sulphone, methyl ethyl sulphone-1,1,1-d3 and methyl ethyl sulphone-1,1,1,3,3-d5 have been presented with vibrational assignmets.Two solid states have been identified in which the molecules are either the trans or the gauche rotational isomers: one solid, the A form, occurs in cooled KBr disks used for infrared spectra while the other was found in CsI disks under ambient conditions.A mixed crystal form has also been found.In the liquid state the enthalpy of the B rotational isomer is slightly less than that of the A isomer by 90 (+/- 140) J mol-1.
- Fawcett, Allan H.,Fee, Sean,Stuckey, Michael,Walkden, Peter
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p. 797 - 804
(2007/10/02)
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- EXCRETION OF S- AND O-METHYL ESTERS AND OTHER VOLATILE COMPOUNDS BY OCHROMONAS DANICA
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The formation of volatile excretion was studied in axenic cultures of Ochromonas danica.Under microaerobic conditions in the light, an accumulation of O- and S-methyl esters, alcohols, dimethyldisulphide was observed in the medium.Most of the compounds are structurally derived from the amino acids methionine, valine , leucine and isoleucine.The excreted volatile compounds, particularly the methyl thioesters, were rapidly metabolized in the dark.Key Word Index - Ochromonas danica; metabolism; volatile excretion products; O-esters; S-esters; microaerobiosis.
- Juettner, Friedrich,Wiedemann, Evi,Wurster, Karl
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p. 2185 - 2188
(2007/10/02)
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