- 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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Read Online
- Synthesis and antifungal activities of alkyl N-(1,2,3-thiadiazole-4-carbonyl) carbamates and S-alkyl N-(1,2,3-thiadiazole-4-carbonyl) carbamothioates
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A series of alkyl N-(1,2,3-thiadiazole-4-carbonyl) carbamates and S-alkyl N-(1,2,3-thiadiazole-4-carbonyl) carbamothioates with unsubstituted or monobrominated straight chain alkyl groups were synthesized and evaluated as fungistatic agents against Gibberella zeae and Altemaria kikuchiana. These compounds showed variable antifungal activities at concentrations of 5 and 50 μg/mL The results showed that antifungal activities depended on the length of the alkyl chain with the optimal chain length of 6-11 carbons. Carbamic acid, (1,2,3-thiadiazole-4-ylcarbonyl)-, hexyl ester (4) showed a strong fungistatic activity against A. kikuchiana at both concentrations, with 90.7 and 54% growth inhibition at 50 and 5 μg/mL, respectively. Carbamic acid, (1,2,3-thiadiazole-4-ylcarbonyl)-, heptyl ester (5); Carbamic acid, (1,2,3-thiadiazole-4-ylcarbonyl)-, octyl ester (6); and Carbamic acid, (1,2,3-thiadiazole-4-ylcarbonyl)-, undecyl ester (9) showed strong fungistatic activity against G. zeae at both concentrations. Their growth inhibitions against G. zeae at the concentration of 5 μg/mL were 78, 63, and 59%, respectively.
- Li, Zaifeng,Wu, Zengru,Luo, Fuying
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- New ways of synthesis of 1,2-dithiole-3-thione
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Two new synthetic approaches to 1,2-dithiole-3-thione are proposed. The title compound is formed by thermolysis of dipropyl polysulfides (n-Pr) 2Sx (x = 3-4) and thermal decomposition of polysulfide dendrimers under reduced pressure. The latter reaction may be recommended for utilization of organochlorine waste products in the manufacture of epichlorohydrin, which are used for the synthesis of dendrimers. 2004 MAIK "Nauka/Interperiodica".
- Korchevin,Russavskaya,Yakimova,Deryagina
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Read Online
- A new procedure for thioester deprotection using thioglycolic acid in both homogeneous and heterogeneous phase
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Classic acetyl thioester protection/deprotection methodologies are widely used in organic synthesis, but deprotection step usually requires harsh conditions not suitable for labile substrates. In this work, a new method for thioester deprotection using a thiotransesterification approach is described. Firstly, thioglycolic acid (TGA) was identified as a good deprotecting reagent in solution. In order to develop a thiol polymer-supported reagent, TGA was anchored to a PEG-based resin through an amide bond (TG-NCO-SH). Both homogeneous and heterogeneous approaches were conveniently carried out at room temperature, in aqueous buffer at pH 8. The mild conditions were suitable for alkyl and phenyl thioesters. Moreover labile thioesters containing thiazolidine and oxazolidine scaffolds, bearing amine, ester and acetal functionalities were also deprotected. The polymer-supported TGA gave better deprotection yields compared to TGA in solution, yields ranging from 61 to 90%. The feasibility of the recovery and reuse of TG-NCO-SH reagent was explored, showing it can be reused at least five times without lossing the activity.
- Mahler, Graciela,Saiz, Cecilia,Villamil, Valentina
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- Phosphorus Pentasulfide Mediated Conversion of Primary Carbamates into Thiols
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In this paper, we report a method for the conversion of primary carbamates into thiols in the presence of phosphorus pentasulfide (P 2 S 5) in refluxing toluene. Presently, no method exists in the literature for conversion of carbamates into thiols and, to the best of our knowledge, it is the first report for this type of conversion. This method presents an indirect route for the conversion of alcohols into thiols via their carbamate derivatives that may be useful in the total synthesis of compounds containing a thiol functionality.
- Maurya, Chandra Kant,Gupta, Pradeep Kumar
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p. 1649 - 1651
(2017/08/11)
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- Two-step three-component process for one-pot synthesis of 8-alkylmercaptocaffeine derivatives
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A highly efficient, odourless and two-step three-component process for one-pot synthesis of some 8-alkylmercaptocaffeine derivatives has been described. The catalyst-free three-component reaction of alkyl bromides, thiourea, and 8-bromocaffeine gave 8-alkylmercaptocaffeine products in excellent to quantitative yields. In addition, the impact of parameters on sample reaction is discussed.
- Rad, M. N. Soltani,Maghsoudi
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p. 70335 - 70342
(2016/08/06)
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- A process for the preparation of isoflavones propanethiol
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The invention discloses a method for synthesizing isopropyl mercaptan from propylene and hydrogen sulfide. According to the method, a heat insulation type fixed bed reactor is used and isopropyl mercaptan is synthesized of hydrogen sulfide and propylene in the presence of a solid acid catalyst according to a continuous production process. The method disclosed by the invention has the advantages that the reaction conditions are easy to control, the yield is high, the process is simple, and the environmental pollution is reduced.
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Paragraph 0052; 0053
(2017/04/03)
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- Quantitative Reactivity Scales for Dynamic Covalent and Systems Chemistry
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Dynamic covalent chemistry (DCC) has become a powerful tool for the creation of molecular assemblies and complex systems in chemistry and materials science. Herein we developed for the first time quantitative reactivity scales capable of correlation and prediction of the equilibrium of dynamic covalent reactions (DCRs). The reference reactions are based upon universal DCRs between imines, one of the most utilized structural motifs in DCC, and a series of O-, N-, and S- mononucleophiles. Aromatic imines derived from pyridine-2-carboxyaldehyde exhibit capability for controlling the equilibrium through distinct substituent effects. Electron-donating groups (EDGs) stabilize the imine through quinoidal resonance, while electron-withdrawing groups (EWGs) stabilize the adduct by enhancing intramolecular hydrogen bonding, resulting in curvature in Hammett analysis. Notably, unique nonlinearity induced by both EDGs and EWGs emerged in Hammett plot when cyclic secondary amines were used. This is the first time such a behavior is observed in a thermodynamically controlled system, to the best of our knowledge. Unified quantitative reactivity scales were proposed for DCC and defined by the correlation log K = SN (RN + RE). Nucleophilicity parameters (RN and SN) and electrophilicity parameters (RE) were then developed from DCRs discovered. Furthermore, the predictive power of those parameters was verified by successful correlation of other DCRs, validating our reactivity scales as a general and useful tool for the evaluation and modeling of DCRs. The reactivity parameters proposed here should be complementary to well-established kinetics based parameters and find applications in many aspects, such as DCR discovery, bioconjugation, and catalysis.
- Zhou, Yuntao,Li, Lijie,Ye, Hebo,Zhang, Ling,You, Lei
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supporting information
p. 381 - 389
(2016/01/26)
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- Interrogation of the Substrate Profile and Catalytic Properties of the Phosphotriesterase from Sphingobium sp. Strain TCM1: An Enzyme Capable of Hydrolyzing Organophosphate Flame Retardants and Plasticizers
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The most familiar organophosphorus compounds are the neurotoxic insecticides and nerve agents. A related group of organophosphorus compounds, the phosphotriester plasticizers and flame retardants, has recently become widely used. Unlike the neurotoxic phosphotriesters, the plasticizers and flame retardants lack an easily hydrolyzable bond. While the hydrolysis of the neurotoxic organophosphates by phosphotriesterase enzymes is well-known, the lack of a labile bond in the flame retardants and plasticizers renders them inert to typical phosphotriesterases. A phosphotriesterase from Sphingobium sp. strain TCM1 (Sb-PTE) has recently been reported to catalyze the hydrolysis of organophosphorus flame retardants. This enzyme has now been expressed in Escherichia coli, and the activity with a wide variety of organophosphorus substrates has been characterized and compared to the activity of the well-known phosphotriesterase from Pseudomonas diminuta (Pd-PTE). Structure prediction suggests that Sb-PTE has a β-propeller fold, and homology modeling has identified a potential mononuclear manganese binding site. Sb-PTE exhibits catalytic activity against typical phosphotriesterase substrates such as paraoxon, but unlike Pd-PTE, Sb-PTE is also able to effectively hydrolyze flame retardants, plasticizers, and industrial solvents. Sb-PTE can hydrolyze both phosphorus-oxygen bonds and phosphorus-sulfur bonds, but not phosphorus-nitrogen bonds. The best substrate for Sb-PTE is the flame retardant triphenyl phosphate with a kcat/Km of 1.7 × 106 M-1 s-1. Quite remarkably, Sb-PTE is also able to hydrolyze phosphotriesters with simple alcohol leaving groups such as tributyl phosphate (kcat/Km = 40 M-1 s-1), suggesting that this enzyme could be useful for the bioremediation of a wide variety of organophosphorus compounds.
- Xiang, Dao Feng,Bigley, Andrew N.,Ren, Zhongjie,Xue, Haoran,Hull, Kenneth G.,Romo, Daniel,Raushel, Frank M.
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p. 7539 - 7549
(2016/01/09)
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- The Ever-surprising chemistry of boron: Enhanced acidity of phosphine·boranes
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The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
- Hurtado, Marcela,Yanez, Manuel,Herrero, Rebeca,Guerrero, Andres,Juan Z. Davalos,Jose-Luis, M. Abboud,Khater, Brahim,Guillemin, Jean-Claude
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supporting information; experimental part
p. 4622 - 4629
(2009/12/29)
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- Process and catalyst for synthesis of mercaptans and sulfides from alcohols
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A process and catalyst blend for selectively producing mercaptans and sulfides from alcohols. The alcohol is reacted with hydrogen sulfide, in the presence of a catalyst blend containing a hydrotreating catalyst and a dehydration catalyst to convert the alcohol to mercaptan or sulfide in one-pass. The alcohols can include primary and secondary alcohols. The mercaptan or sulfide having less than about 30% unreacted alcohol contained therein.
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(2008/06/13)
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- Catalytic synthesis of thiols from alcohols and hydrogen sulfide
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The basic features of the reaction of thiol synthesis from hydrogen sulfide and methanol, n-propanol, n-butanol, or n-dodecanol in the presence of acid-base catalysts was studied. The catalysts with paired surface sites-weak Lewis acid sites and strong base sites-have a low activity but are selective in thiol formation. The catalysts with strong acid sites exhibited a high activity in the conversion of alcohols but were not selective in the formation of thiols. In the presence of proton-donor catalysts, the thiolation of methanol alone took place; other alcohols underwent only dehydration. The thiolation of methanol on various catalysts yielded dimethyl sulfide along with metanethiol; no dialkyl sulfides was produced in the reaction of hydrogen sulfide with higher alcohols. Copyright
- Mashkina
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- 2,3-disubstituted cyclopentanone derivatives, process for producing the same, and medicinal use thereof
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The present invention relates to a compound represented by the following general formula (1) STR1 (wherein X represents O, S, SO, SO2, or NH, Y is a substituted or unsubstituted hydrocarbon residue containing 1 through 6 carbon atoms and having an overall molecular weight of not less than 15 and not more than 400, and the hydrocarbon residue, when the residue is ring, may contain one or two hetero-atoms in the ring, and Z is a carboxyl group, a group derived therefrom or an aliphatic hydrocarbon residue having from 1 to 4 carbon atoms which may be substituted or unsabstituted) or a pharmacologically acceptable salt thereof (excluding (1R,2S)-2-[(2R)-(2-acetyl-amino-2-carboxyethyl)thiomethyl]-3-oxo-1-cyclopentane-carboxylic acid (cystacyclin)), a method for production thereof and a medicinal use thereof. The compound of the present invention is useful as a neuron differentiation accelerator.
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- METHOD FOR TREATING ANXIETY WITH MUSCARINIC CHOLINERGIC RECEPTOR AGONISTS
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The present invention relates a method for treating anxiety using azacyclic and azabicyclic pyrazine compounds.
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- Mechanism of the Solution-Phase Reaction of Alkyl Sulfides Atomic Hydrogen. Reduction via a 9-S-3 Radical Intermediate
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The low selectivity of benzyl alkyl sulfide fragmentation subsequent to its reaction with atomic hydrogen is indicative of a reaction that proceeds via an early transition state. The competitive reduction of a series of substituted-benzyl alkyl sulfides was insensitive to the substituent on the aromatic ring (ρ = -0.13, r = 0.99). The relative rates of fragmentation of a series of the substituted-benzyl alkyl sulfides gave a V-shaped Hammett plot. Both electron-donating and electron-withdrawing groups destabilized the transition state (ρ = +0.99, r = 0.999; ρ = -0.82, r = 0.992). Since the relative rates of disappearance of the alkyl benzyl sulfides are not substituent dependent, but the relative rates of fragmentation are, a 9-S-3 intermediate is preferred as the structure leading to products.
- Tanner, Dennis D.,Koppula, Sudha,Kandanarachchi, Pramod
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p. 4210 - 4215
(2007/10/03)
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- Use of azacyclic or azabicyclic pyrazine compounds for treating anxiety
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The present invention relates a method for treating anxiety using azacyclic and azabicyclic pyrazine compounds.
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- Thiyl radicals in gas-phase thermolysis of xanthic acid esters
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Gas-phase thermolysis of xanthic acid esters and their reaction with acetylene at 250-600°C have been studied for the first time. The direction of the thermolysis is determined by the nature of the substituents at the oxygen and sulfur atoms. The main products of the thermolysis are gaseous hydrocarbons, carbon monoxide and hydrogen sulfide. The yields of liquid products of the thermolysis and of the reactions with acetylene are 4-46 %. The role of thiyl radicals in thiophene molecule formation and reaction routes to carbon disulfide, dithiocarbonates, and stilbene are discussed.
- Deryagina,Korchevin,Russavskaya,Sukhomazova,Levanova
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p. 140 - 143
(2007/10/03)
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- HIGH-TEMPERATURE ORGANIC SYNTHESIS XXXVIII. THERMAL SYNTHESIS OF 1,2-DITHIOLE-3-THIONES FROM POLYSULFIDES
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The main product from the thermolysis of dipropyl polysulfides (C3H7)2Sn (n = 3-4) at 350-400 deg C is 1,2-dithiole-3-thione, and it is formed with yields of up to 52 percent. 4-Methyl-1,2-dithiole-3-thione was obtained from diisobutyl polysulfides (iso-C4H9)2Sn under analogous conditions with a yield of 68 percent.
- Turchaninova, L. P.,Sukhomazova, E. N.,Korchevin, N. A.,Deryagina, E. N.,Voronkov, M. G.
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p. 435 - 437
(2007/10/02)
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- EFFET PROMOTEUR DES PHOSPHITES ALIPHATIQUES DANS L'ADDITION PHOTO AMORCEE D'H2S SUR LE PROPYLENE EN SOLUTION. I - ETUDE ANALYTIQUE
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Aliphatic phosphites have a promotor effect in the radical addition in solution of H2S to propylene photoinitiated as well by direct H2S irradiation as by added benzophenone irradiation.For this last reaction, the phosphite used being (CH3O)3P, the solvent polarity has no effect on the reaction.When the solvent used is a poor hydrogen donnor in a radical reaction, such as benzene, there is an induction period in the case of the benzophenone photoinitiated reaction performed in the presence of a phosphite.It increases for a given aliphatic phosphite with the phosphite concentration and varies with the aliphatic phosphites structure.Light intensity has nearly no effect on the development of the last reaction.
- Brehon, Annick,Couture, Axel,Combier, Lablache A.
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p. 839 - 850
(2007/10/02)
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- REACTION D'ADDITION EN SOLUTION D'H2S SUR LE PROPYLENE PHOTOINITIEE PAR LA BENZOPHENONE EN PRESENCE DE PHOSPHITES ALIPHATIQUES. IV - ETUDE MECANISTIQUE DU ROLE PROMOTEUR DES PHOSPHITES ALIPHATIQUES
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Aliphatic phosphites have no promotor effect on the addiditon of radical O=C.-NH2 or CH3C.=O on an olefin, but only on the addition of HS. or RS..The promotor effect of (CH3O)3P occur whatever the initiation step of the chain radical reaction.Phosphites interfere with the chain propagation steps of the reaction.The crucial species are (CH3O)3PSH and one of its dimer.A kinetic, based on this assumption gives data which are in agreement with the experimental fact.
- Brehon, Annick,Couture, Axel,Lablache-Combier, A.
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p. 873 - 882
(2007/10/02)
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- Rate Constants and Equilibrium Constants for Thiol-Disulphide Interchange Reactions Involving Oxidized Glutathione
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The rate of reduction of oxidized glutathione (GSSG) to glutathione (GSH) by thiolate (RS-) follows a Broensted relation in pKas of the conjugate thiols (RSH): βnuc ca. 0.5.This value is similar to that for reduction of Ellman's reagent: βnuc ca. 0.4 - 0.5.Analysis of a number of rate and equilibrium data, taken both from this work and from the literature, indicates that rate constants, k, for a range of thiolate-disulphide interchange reactions are correlated well by equations of the form log k = C + βnucpKanuc + βcpKac + βlgpKalg ( nuc = nucleophile, c = central, and lg = leaving group sulfur): eq 36 - 38 give representative values of the Broensted coefficients.The values of these Bronsted coefficients are not sharply defined by the available experimental data, although eq 36 - 38 provide useful kinetic models for rates of thiolate-disulfide interchange reactions.The uncertainty in these parameters is such that their detailed mechanistic interpretation is not worthwhile, but their qualitative interpretation - that all three sulphur atoms experience a significant effective negative charge in the transition state, but that the charge is concentrated on the terminal sulfurs - is justified.Equilibrium constants for reduction of GSSG using α,ω-dithiols have been measured.The reducing potential of the dithiol is strongly influenced by the size of the cyclic disulfide formed on its oxidation: the most strongly reducing dithiols are those which can form six-membered cyclic disulfides.Separate equilibrium constants for thiolate anion-disulphide interchange (KS-) and for thiol-disufide interchange (KSH) have been estimated from literature data: KS- is roughly proportional to 2ΔpKa is the difference between the pKas of the two thiols involved in the interchange.The contributions of thiol pKa values to the observed equilibrium constants for reduction of GSSG with α,ω-dithiols appear to be much smaller than those ascribable to the influence of structure on intramolecular ring formation.These equilibrium and rate constants are helpful in choosing dithiols for use as antioxidants in solutions containing proteines: dithiothreitol (DTT), 1,3-dimercapto-2-propanol (DMP), and 2-mercaptoethanol have especially useful properties.
- Szajewski, Richard P.,Whitesides, George M.
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p. 2011 - 2026
(2007/10/02)
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- Photoreduction and Photoarylation of O-Ethyl S-n-Propyl Phenylphosphonothioate
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U.v. irradiation (254 nm) of O-ethyl S-n-propyl phenylphosphonothioate (1) in EtOH leads to a rapid photoreductive cleavage of the phosphorus-sulphur (Φ = 0.14) or the sulphur-carbon (Φ = 0.05) bond, as evidenced by the formation of O-ethyl phenylphosphinate, n-propanethiol, O-ethyl phenylphosphonothioic acid, and propane as the major products.The concomitant photo-oxidation of EtOH to acetaldehyde is also observed.The rate of photoreduction of (1) is independent of the hydrogen-donor capacity of the solvent (MeOH, EtOH, or PriOH).Hence the reaction proceeds without prior hydrogen abstraction, probably by direct homolysis of the excited state of (1).In accordance with this, in situ spin-trapping experiments show the intermediacy of the phosphonyl radical EtO(Ph)P(O).Sensitizers with a triplet energy 80 kcal mol-1 sensitize the photoreduction of (1).Sensitization by aromatic hydrocarbons, e. g. benzene, in found to be complicated by simulataneous photoarylation of (1), which leads to the formation of O-ethyl diphenylphosphinate.
- Benschop, Hendrik P.,Konings, Cornelis A. G.,Platenburg, Dominique H. J. M.,Deen, Rudolf
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p. 198 - 205
(2007/10/02)
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- Leaving Group Effects in Thiolester Alkaline Hydrolysis. Part 1. A Keten-mediated (E1cB) Pathway for Basic Hydrolysis of S-Acetoacetylcoenzyme A and Analogues
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The basic hydrolysis of a series of leaving-group substituted acetothiolacetates (CH3COCH2COSR) has been studied in aqueous media.Hydrolysis of N-acetyl-S-acetoacetylcysteinamine follows a kinetic ionisation curve with an inflexion corresponding to the pK of this ester as determined by spectrophotometric and electrometric titrations.The rate constant at high pH was shown to follow a Broensted relationship with βL.G. -1.13, where βL.G. is the slope of a plot of the logarithm of the rate constant versus the pKa of the conjugate acid of the leaving group.This, and other evidence from rate comparisons, activation parameters, and kinetic solvent isotope effects, indicated an E1cB hydrolytic mechanism involving unimolecular collapse of the ester enolate ions via a ketenoid transition-state.S-Acetoacetylcoenzyme-A was also hydrolysed in base by this mechanism.Direct comparison of rates of leaving group expulsion for ArS and ArO was possible by means of this unimolecular process.For a leaving group with pKL.G. 10, the oxyanion departs ca. 1 or 2 orders of magnitude faster than the thiolate anion; for pKL.G. 6.0, the advantage of oxygen over sulphur is 103-104 fold.In a direct structural comparison, PhS departs 32 times as rapidly as PhO.The contribution of steric release in the E1cB transition-state for S-t-butyl acetothiolacetate hydrolysis is discussed.The pKa values of some acetothiolacetates were measured.
- Douglas, Kenneth T.,Yaggi, Norbert F.
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p. 1037 - 1044
(2007/10/02)
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- Antimicrobial composition and method containing N-(3,5-dihalophenyl)-imide compounds
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Novel N-(3,5-dihalophenyl)imide compounds, which exhibit a strong antimicrobial activity against microorganisms including phytopathogenic fungi, parasites of industrial products and pathogenic microorganisms, represented by the formula, STR1 wherein X and X' each represent halogens and A represents a substituted ethylene such as chloroethylene, C1 - C4 alkylthioethylene, C1 - C2 alkyl-ethylene or 1,2-di-C1 - C2 -alkyl-ethylene, a cyclopropylene such as 1,3-dimethylcyclopropylene, trimethylene, a cyclohexylene-1,2-, cyclohexenylene-1,2-, cyclohexadienylene-1,2- or o-phenylene. The N-(3,5-dihalophenyl)imide compounds can be obtained by any of methods which produce imide compounds or reaction of an N-(3,5-dihalophenyl)maleimide compound with a mercaptan, a hydrogen halide, phosphorus chloride or thionylchloride.
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