- Oxidative Cyclization of 4-(2-Mercaptophenyl)-Substituted 4H-1,2,4-Triazolium Species to Tricyclic Benzothiazolium Salts
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Herein we report a generally applicable method for the preparation of N-substituted benzo[4,5]thiazolo[2,3-c][1,2,4]triazol-1-ium salts from air stable precursors. This transformation features selective deprotection of a para-methoxybenzyl protected thiol followed by C?H functionalization of the linked 1,2,4-triazolium salts under oxidative conditions. Using this procedure, we synthesized a variety of tricyclic thiazolium salts which contain both electron-withdrawing and electron-donating aromatic substituents as well as aliphatic substituents. Our approach also tolerates many functional groups including alkynes, alcohols, diols, amides, and polyethers.
- Ardón-Mu?oz, Luis G.,Bolliger, Jeanne L.
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- Novel synthesis method of chlorolucanthone
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The invention discloses a novel synthesis method of chlorolucanthone, and belongs to the technical field of chemical engineering. The method comprises the following steps: firstly, adding a sodium hydrosulfide solution into a hydrogen sulfide generator, then dropwise adding an acid into the hydrogen sulfide generator, and guiding generated gas into a preheated pipeline reactor; pumping preheated p-dichlorobenzene into the pipeline reactor, reacting the p-dichlorobenzene with hydrogen sulfide gas, cooling a reaction product to obtain liquid and gas, and rectifying and purifying the liquid to obtain mercaptochlorobenzene; secondly, adding a reaction solvent and an alkali into a flask, stirring, adding mercaptochlorobenzene and o-chlorobenzoic acid, carrying out a reflux reaction, and carrying out aftertreatment after the reaction is finished so as to obtain an intermediate 2-carboxyl-4'-chlorodiphenyl sulfide; and finally, adding 2-carboxyl-4'-chlorodiphenyl sulfide into concentrated sulfuric acid, carrying out an intramolecular cyclization dehydration reaction, and purifying after the reaction is ended so as to obtain the target product. The method disclosed by the invention is simple and convenient to operate, mild in reaction condition, clean and environment-friendly, and high in product yield and purity.
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Paragraph 0029; 0031; 0034; 0036; 0039; 0041; 0044; 0046
(2020/10/21)
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- High-performance sono/nano-catalytic system: Fe3O4?Pd/CaCO3-DTT core/shell nanostructures, a suitable alternative for traditional reducing agents for antibodies
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Herein, a novel heterogeneous nanoscale reducing agent for antibody cleavage, made of iron oxide nanoparticles, silica network, palladium on calcium carbonate (10%), and dithiothreitol (Fe3O4?Pd/CaCO3-DTT), is presented as a substantial alternative for traditional homogeneous analogues. Conventionally, antibody fragmentation is accomplished using reducing agents and proteases that digest or cleave certain portions of the immunoglobulin protein structure to provide active thiol sites for drug tagging aims. Then, dialysis process is needed to separate excess chemical structures and purify the reduced antibody. In this work, we have made an effort to design a suitable heterogeneous tool for protein cleavage and skip the dialysis process for purification of the reduced antibody. In this regard, firstly, various preparation methods including microwave irradiation, reflux and ultrasonication have been precisely compared, and it has been proven that the best result is obtained through 10 min ultrasound (US) irradiation using an US bath with 50 KHz frequency and 200 W L?1 power density. Then, all the necessary structural analyses have been done and thoroughly interpreted for the final product. Afterward, the catalytic performance of Fe3O4?Pd/CaCO3-DTT nanoscale system in the presence of US waves (50 KHz, 200 W) has been monitored using some disulphide derivatives. The NPs could be conveniently separated from the mixture through their substantial paramagnetic property. Thus, dialysis process in which various types of membranes are used is practically jumped after the reduction process. In this work, this is clearly demonstrated that there is a constructive synergistic effect between US waves and prepared Fe3O4?Pd/CaCO3-DTT nanoscale reducing agent. Ultimately, trastuzumab (anti HER-2) antibody has been used to test the performance of the prepared Fe3O4?Pd/CaCO3-DTT NPs in a real protein reduction reaction.
- Taheri-Ledari, Reza,Maleki, Ali,Zolfaghari, Ehsan,Radmanesh, Maral,Rabbani, Hodjattallah,Salimi, Ali,Fazel, Ramin
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- Novel synthesis method for thiophenol derivative
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The invention discloses a novel synthesis method for a thiophenol derivative, and belongs to the technical field of synthesis. The method comprises the steps that a diphenyl sulfide derivative of thegeneral formula II and hydrogen sulfate are adopted as raw materials, a tubular reactor is used as a reactor, and an equimolar quantitative reaction is performed under the normal pressure and the temperature of 330-350 DEG C to synthesize the thiophenol derivative of the general formula I. By adopting the method, the raw material utilization rate can reach 100%, no solvent or catalyst needs to beadopted in the reaction, the reaction temperature is low, and the product yield and purity are high.
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Paragraph 0018; 0035-0037
(2019/04/30)
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- Preparation method of 4-chlorothiophenol
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The invention relates to a simple preparation method of 4-chlorothiophenol. 4-chlorobenzenesulfonyl chloride is prepared from sodium 4-chlorobenzenesulfonate and thionyl chloride as raw materials andtoluene as a solvent through a reaction at 50-70 DEG C for 3-5 h under the action of a phase transfer catalyst and reduced by iron powder at the temperature of 40-60 DEG C under an acidic condition, and 4-chlorothiophenol is obtained. The method has the characteristics of being low in cost, simple and convenient to operate and suitable for industrial production.
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Paragraph 0017; 0019
(2018/04/26)
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- Preparation method for synthesizing thiophenol compound based on sodium sulfide nonahydrate
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The invention provides a preparation method for synthesizing a thiophenol compound based on sodium sulfide nonahydrate. In an inert gas protective atmosphere, substituted iodobenzene and a sulfhydrylation reagent are added into an aprotic polar solvent, then a copper salt catalyst and a ligand compound are orderly added into the solution, the mixed solution undergoes a reaction at a temperature of 90 to 120 DEG C for 12-24h, and the reaction solution is cooled to the room temperature and is acidized so that the product is obtained. The preparation method has the advantages of simple reaction conditions, good compatibility of functional groups, high yield and small environmental pollution. Thiophenol is an important intermediate for pharmaceutical chemical synthesis and has a very wide application range in fields of chemical raw materials, pesticides and medicines. The preparation method has a great use value and good social and economic benefits.
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Paragraph 0035; 0036
(2017/08/30)
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- Copper-Catalyzed Direct Synthesis of Aryl Thiols from Aryl Iodides Using Sodium Sulfide Aided by Catalytic 1,2-Ethanedithiol
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A copper-catalyzed direct and effective synthesis of aryl thiols from aryl iodides using readily available Na 2 S·9H 2 O and 1,2-ethanedithiol was described. A variety of aryl thiols were readily obtained in yields of 76-99%. In this protocol, Na 2 S·9H 2 O was used as ultimate sulfur source, and 1,2-ethanedithiol functioned as an indispensable catalytic reagent.
- Xue, Hongyu,Jing, Bing,Liu, Shasha,Chae, Junghyun,Liu, Yajun
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p. 2272 - 2276
(2017/10/06)
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- The aromatic thiol compound (by machine translation)
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[A] at a high rate, and, high purity aromatic thiol compound method. [Solution] the presence of metal sulfide, with a compound represented by formula (1), by a vapor phase reaction of hydrogen sulfide, (2) an aromatic thiol compound represented by the formula manufacturing method. (R are each independently, C1 a-4 alkyl group, a hydroxyl group, amino group, cyano group, nitro group, C1 a-2 alkoxy group or a halogen atom; n is an integer of 0 - 5; X is a halogen atom)[Drawing] no (by machine translation)
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-
Paragraph 0084; 0085
(2017/10/31)
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- The Chan-Lam reaction of chalcogen elements leading to aryl chalcogenides
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A copper-catalyzed chalcogenation of arylboronic acids with elemental sulfur or selenium is established, which provides diaryl disulfides or diaryl monoselenides in moderate to good yields with excellent selectivities, respectively. Moreover, after sequential reduction and coupling with aryl/alkyl iodides in one pot, unsymmetrical monosulfides were obtained in good yields.
- Yu, Jin-Tao,Guo, Huan,Yi, Yuanqiuqiang,Fei, Haiyang,Jiang, Yan
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supporting information
p. 749 - 752
(2014/04/03)
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- Novel one-pot synthesis of thiophenols from related triazenes under mild conditions
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In this work, at first, triazenes were synthesized from primary aryl amines. Afterwards, triazenes were converted into the corresponding thiophenols in one-pot using sodium sulfide in acidic media, by in situ generation of diazonium counterion beside hydrogen sulfide as anionic sulfur nucleophile at room temperature. The procedure can be a convenient shortcut for the preparation of thiophenols from primary aryl amines. Georg Thieme Verlag Stuttgart · New York.
- Khazaei, Ardeshir,Kazem-Rostami, Masoud,Moosavi-Zare, Ahmadreza,Bayat, Mohammad,Saednia, Shahnaz
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experimental part
p. 1893 - 1896
(2012/09/22)
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- CuI-nanoparticles-catalyzed selective synthesis of phenols, anilines, and thiophenols from aryl halides in aqueous solution
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CuI-nanoparticles-catalyzed selective synthesis of phenols, anilines, and thiophenols from aryl halides was developed in the absence of both ligands and organic solvents. Anilines were formed selectively with ammonia competing with hydroxylation and thiophenols were generated selectively with sulfur powder after subsequent reduction competing with hydroxylation and amination.
- Xu, Hua-Jian,Liang, Yu-Feng,Cai, Zhen-Ya,Qi, Hong-Xia,Yang, Chun-Yan,Feng, Yi-Si
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p. 2296 - 2300
(2011/06/17)
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- Kinetics and mechanism of the aminolysis of O-methyl S-aryl thiocarbonates in acetonitrile
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The aminolysis of O-methyl S-aryl thiocarbonates with benzylamines are studied in acetonitrile at -45.0°C. The βX (βnuc) values are in the range 0.62-0.80 with a negative cross-interaction constant, ρXZ = -0.42, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H 4CH2ND2) are large, kH/kD = 1.29-1.75, suggesting that the N-H(D) bond is partially broken in the transition state by forming a hydrogen-bonded four-center cyclic structure. The concerted mechanism is enforced by the strong push provided by the MeO group which enhances the nucleofugalities of both benzylamine and arenethiolate from the putative zwitterionic tetrahedral intermediate.
- Oh, Hyuck Keun
-
scheme or table
p. 1539 - 1542
(2011/12/04)
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- Kinetics and mechanism of the aminolysis of aryl N-benzyl thiocarbamates in acetonitrile
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The aminolysis reactions of phenyl N-benzyl thiocarbamate with benzylamines in acetonitrile at 50.0 °C are investigated. The reactions are first order in both the amine and the substrate. Under amine excess, pseudo-first coefficient (kobs) are obtained, plot of kobs vs free amine concentration are linear. The signs of ρXZ (X and ρZ with respect to the sustituent in the substrate and large ρXZ value indicate that the reactions proceed concerted mechanism. The normal kinetic isotope effects (kH/k D = 1.3 ～ 1.5) involving deuterated benzylamine nucleophiles suggest a hydrogen-bonded, four-centered-type transition state. The activation parameters, ΔH?and AS?, are consistent with this transition state structure.
- Oh, Hyuck Keun
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experimental part
p. 137 - 140
(2011/11/01)
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- A study of the kinetics of La3+-promoted methanolysis of S-aryl methylphosphonothioates: Possible methodology for decontamination of EA 2192, the toxic byproduct of VX hydrolysis
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The kinetics of the La3+-catalyzed methanolysis of a series of S-aryl methylphosphonothioates (4a-e, phenyl substituents = 3,5-dichloro, 4-chloro, 4-fluoro, 4-H, 4-methoxy) were studied at 25 °C with ss pH control. The reaction involves saturation binding of the anionic substrates to dimeric La3+/methoxide catalysts formulated as La2 3+(-OCH3)x, where x = 2-5 depending on the solution ss pH. Cleavage of the La3+-bound methylphosphonothioates is fast, ranging from 5 × 10-3 s -1 to 5.5 × 10-5 s-1 for substrates 4a-e at a ss pH of 8.4 and 1.6 × 10-1 s-1 to 4 × 10-3s-1 at a ss pH of 11.7. The rate accelerations for the methanolysis of substrates 4a-e, relative to their background methoxide-promoted reactions, average 7 × 1010 and 1.5 × 109, respectively, at sspH's of 8.4 and 11.7. The catalytic system is predicted to cleave EA 2192 (S-2(N,N-di-iso-propylaminoethyl) methylphosphonothioate), a toxic byproduct of the hydrolysis of VX, with a t1/2 between 4 and 8 min at a ss pH of 8.4, and 27 min at a ss pH of 11.7.
- Dhar, Basab B.,Edwards, David R.,Brown, R. Stan
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p. 3071 - 3077
(2011/05/09)
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- Copper-catalyzed coupling of thiourea with aryl iodides: The direct synthesis of aryl thiols
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A general, economical and efficient protocol for the direct copper-catalyzed coupling of thiourea with aryl iodides is developed and it will be potentially applied in large-scale industry as a preferred process.
- Qiao, Shu,Xie, Kun,Qi, Junsheng
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scheme or table
p. 1441 - 1443
(2011/01/04)
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- Regio- and enantioselective intermolecular hydroacylation: Substrate-directed addition of salicylaldehydes to homoallylic sulfides
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We report a Rh-catalyzed, regio- and enantioselective intermolecular olefin hydroacylation under mild conditions. Hydroacylations between homoallylic sulfides, containing a substrate-bound directing group, and salicylaldehyde derivatives occur in the presence of a spiro-phosphoramidite ligand, (R)-SIPHOS-PE, to give α-branched ketones in >20:1 selectivity and up to 97% ee. Our conditions are also applicable to the asymmetric intermolecular hydroacylation of 1,2-disubstituted olefins.
- Coulter, Matthew M.,Kou, Kevin G. M.,Galligan, Baye,Dong, Vy M.
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supporting information; experimental part
p. 16330 - 16333
(2011/02/23)
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- A simple, fast and chemoselective method for the preparation of arylthiols
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An efficient and convenient method for the synthesis of arylthiols by reaction of sulfonyl chlorides with triphenylphosphine in toluene is reported.
- Bellale, Eknath V.,Chaudhari, Mahesh K.,Akamanchi, Krishnacharya G.
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experimental part
p. 3211 - 3213
(2010/03/01)
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- Novel N,S-phenacyl protecting group and its application for peptide synthesis
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The phenacyl group can be introduced onto amino and thio groups by N,S-alkylation reactions. Conversely, these groups are removed rapidly by employing magnesium in acetic acid. This protecting group was successfully applied to a short peptide synthesis of Boc-L-Cys-Gly-OMe. Georg Thieme Verlag Stuttgart.
- Tang, Guo,Ji, Tao,Hu, An-Fu,Zhao, Yu-Fen
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experimental part
p. 1907 - 1909
(2009/04/11)
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- Reliable and general method for the cleavage of α-arylheteroatom- substituted carboxylic acids
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Bonds between arylheteroatom moieties and α-carbons of carboxylic acids are efficiently cleft by azide transfer and subsequent Curtius rearrangement. The scope of the one-pot protocol covers differently substituted carboxylic acids and heteroatoms like O, S, Se, and N. Georg Thieme Verlag Stuttgart.
- Spurg, Anke,Waldvogel, Siegfried R.
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p. 3042 - 3044
(2008/03/12)
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- Catalytic decomposition of simulants for chemical warfare V agents: Highly efficient catalysis of the methanolysis of phosphonothioate esters
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(Chemical Equation Presented) As good as the original: Extremely effective methanolysis of phosphonothioates using metal-containing systems (e.g., 1) was achieved. The catalytic methanolysis of a SCH2CH2NEt 2 derivative, an analogue of the organophosphorus chemical warfare material VX, was predicted, and the catalyzed methanolysis of S-(3,5-dichlorophenyl) O-ethyl methylphosphonothioate was shown to involve a concerted displacement of the aryl thioate (transition state 2)
- Melnychuk, Stephanie A.,Neverov, Alexei A.,Brown, R. Stan
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p. 1767 - 1770
(2007/10/03)
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- Mechanistic studies of la3+- And Zn2+-catalyzed methanolysis of aryl phosphate and phosphorothioate triesters. Development of artificial phosphotriesterase systems
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The methanolyses of a series of O,O-diethyl O-aryl phosphates (2,5) and O,O-diethyl S-aryl phosphorothioates (6) promoted by methoxide and two metal ion systems, (La3+)2(-OCH3)2 and 4:Zn2+:-OCH3 (4 = 1,5,9- triazacyclododecane) has been studied in methanol at 25°C. Bronsted plots of the log k2 values vs. sspKa for the phenol leaving groups give βlg values of -0.70. -1.43 and -1.12 for the methanolysis of the phosphates and -0.63, -0.87 and -0.74 for the methanolysis of the phosphorothioates promoted by the methoxide, La 3+ and Zn2+ systems respectively. The kinetic data for the metal-catalyzed reactions are analyzed in terms of a common mechanism where there is extensive cleavage of the P-XAr bond in the rate-limiting transition state. The relevance of these findings to the mechanism of action of the phosphotriesterase enzyme is discussed. The Royal Society of Chemistry 2005.
- Liu, Tony,Neverov, Alexei A.,Tsang, Josephine S.W.,Brown, R. Stan
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p. 1525 - 1533
(2007/10/03)
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- Thermal reactions of chloroarenes with hydrogen sulfide in the presence of methanol
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Gas-phase reactions of chloroarenes (ClC6H4X, X = H, 4-CH3, 4-OH, 4-Cl, 4-CF3) with hydrogen sulfide or its precursors were investigated in the presence of methanol, which was a stronger H-donor than hydrogen sulfide. Introducing methanol increased the selectivity of arenethiols formation at X = H and 4-CH3 and did not affect the reaction selectivity at acceptor X. The efficiency of methanol influence was considered from the viewpoint of free-radical reaction mechanism and the stability of the arenethiyl radicals. 2005 Pleiades Publishing, Inc.
- Deryagina,Sukhomasova,Levanova,Papernaya,Korchevin
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p. 1624 - 1630
(2007/10/03)
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- Oxidation/reduction interconversion of thiols and disulfides using hydrogen and oxygen catalyzed by a rhodium complex
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RhH(PPh3)4 catalyzes reduction of disulfides to thiols by hydrogen and RhH(PPh3)4/1,4- bis(diphenylphosphino)butane (dppb) catalyzes oxidation of thiols to disulfides by oxygen.
- Arisawa, Mieko,Sugata, Chiyoshi,Yamaguchi, Masahiko
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p. 6097 - 6099
(2007/10/03)
-
- Kinetics and mechanism of the aminolysis of S-aryl O-ethyl dithiocarbonates in acetonitrile
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The aminolysis of S-aryl O-ethyl dithiocarbonates with benzylamines are studied in acetonitrile at -25.0°C. The βX (βnuc) values are in the range 0.67-0.77 with a negative cross-interaction constant, ρXZ = -0.24, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H4CH 2ND2) are large, kH/kD = 1.41-1.97, suggesting that the N-H(D) bond is partially broken in the transition state by forming a hydrogen-bonded four-center cyclic structure. The concerted mechanism is enforced by the strong push provided by the EtO group which enhances the nucleofugalities of both benzylamine and arenethiolate from the putative zwitterionic tetrahedral intermediate.
- Oh, Hyuk Keun,Oh, Ji Young,Sung, Dae Dong,Lee, Ikchoon
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p. 2174 - 2182
(2007/10/03)
-
- Nucleophilic Substitution Reactions of Aryl N-Phenyl Thiocarbamates with Benzylamines in Acetonitrile
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The aminolysis reactions of aryl N-phenythiocarbamates (PhNHC(=O)SC 6H4Z; 3b) with benzylamines (XC6H 4CH2NH2) acetonitrile are studied. Rates are much faster than the corresponding reactions of aryl N-phenylcarbamates (PhNHC(=O)OC6H4Z; 3a). The rate increase from 3a to 3b is greater than that expected from substitution of thiophenoxide for phenoxide leaving group in the stepwise aminolysis reactions of esters. This large rate increase and the similar change in the aminolysis rates that are reported to occur from aryl ethyl carbonate (EtOC(=O)OC6H4Z; 2a) to aryl ethylthiocarbonate (EtOC(=O)SC6H4Z; 2b) lead us to conclude that the aminolysis of 3b proceeds by a concerted mechanism in contrast to a stepwise process for 3a. The negative ρxz values (-0.63) and violation of the reactivity-selectivity principle (RSP) support the proposed mechanism. The large βx values (1.3-1.5) obtained are considered to indicate a large degree of bond making in the transition state, which is consistent with the relatively large kinetic isotope effects (k H/kD > 1.0) observed.
- Oh, Hyuck Keun,Park, Jie Eun,Sung, Dae Dong,Lee, Ikchoon
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p. 3150 - 3153
(2007/10/03)
-
- Kinetics and mechanism of the aminolysis of aryl propanedithioates in acetonitrile
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The kinetics and mechanism of the aminolysis of aryl proanedithioates with benzylamines are investigated in acetonitrile at - 35.0 °C. A large magnitude of the Hammett (ρx and ρz) and Broensted (βx and βz) coefficients and exceptionally large cross-interaction constant ρxz(= 3.5) are consistent with a stepwise mechanism in which leaving group expulsion from an intermediate, T±, is the rate-determining step. The faster rates observed for dithio esters (I1) than for thio esters (I), and the validity of the reactivity-selectivity principle (RSP) are also in line with the mechanism proposed. The kH/kD values (= 1.0-1.8) determined with deuterated benzylamines (XC6H4CH2ND2) and the activation parameters, ΔH≠(?8 kcal mol-1) and ΔS≠(= -16 to -23 e.u.), suggest that proton transfer occurs concurrently with leaving group departure in the transition state.
- Hyuck Keun Oh,Sun Kyung Kim,Hai Whang Lee,Lee
-
p. 313 - 317
(2007/10/03)
-
- An efficient synthetic route to aryl thiocyanates from arenesulfinates
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An efficient procedure for the conversion ot the inexpensive and readily available arenesulfinate (sodium) salts in three steps into the corresponding aryl thiocyanates is described. Overall yields are high, and the presence of both electron-with drawing and electron-donating substituents is well tolerated.
- Still,Watson
-
p. 1355 - 1359
(2007/10/03)
-
- Reductions using LiCl/NaBH4: A rapid and efficient cleavage of organic disulfides to mercaptans
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A practical and novel reagent system LiCl/NaBH4 is used for the reductive cleavage of organic disulfides to mercaptans under mild conditions, in excellent yields.
- Rajaram,Purushothama Chary,Iyengar
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p. 622 - 624
(2007/10/03)
-
- Unexpected catalyzed C=C bond cleavage by molecular oxygen promoted by a thiyl radical
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Olefin oxidation with molecular oxygen, promoted by a transition metal catalyst and a thiophenol, involved C=C bond cleavage into the corresponding carbonyl derivatives. This new reaction proceeds under one atmosphere of oxygen, at room temperature, in the presence of an excess of thiophenol and a catalyst such as MnL2 3a or VC1L2 3c. It was applied to aromatic and aliphatic olefins, as well as to functionalized or unfunctionalized acyclic compounds, providing the corresponding ketones and aldehydes in up to 98% yield. The synthetic interest of this catalytic oxidation was illustrated by a one-step preparation of the fragrance (-)-4-acetyl-1-methylcyclohexene 7e in 73% isolated yield. The C=C bond cleavage probably results from a catalyzed decomposition of the β-hydroperoxysulfide intermediate 12 that is formed by the radical addition of thiophenol to the olefin in the presence of oxygen. Although an excess of the thiophenol was used, it was transformed into the disulfide which could then be reduced without purification in 83% overall yield, thereby allowing for recycling. In addition, the C=C bond cleavage under oxygen could be promoted by catalytic quantities of the thiyl radical, generated by photolysis of the disulfide; thus, in the presence of 0.1 equiv of bis(4-chlorophenyl) disulfide 4b and 5% of the manganese complex 3a, trans-methylstilbene 1b gave, under radiation, benzaldehyde 6a and acetophenone 7a in up to 95% yield. This new reaction offers an alternative to the classical C=C bond cleavage procedures, and further developments in the fields of bioinorganic and environmental chemistry are likely.
- Baucherel,Uziel,Juge
-
p. 4504 - 4510
(2007/10/03)
-
- One-step arylthiolation of aromatic compounds by disulfide radical cations generated from oxidation of diaryl disulfides with aluminium chloride
-
Reactions of di(phenyl and 4-tolyl) disulfides 1a and 1b with PhX 3a-e (X = H, Me, Et, Ph and Cl) in the presence of AlCl3 at 25°C give diaryl sulfides 4-6 by aromatic arylthiolation via the disulfide radical cations 2, along with thiophenols 7 formed in the incomplete reactions. Competitive intramolecular reactions of 2a also yield diphenyl sulfide 4a or/and thianthrene 8. However, the reactions of bis(4-chlorophenyl and 4-fluorophenyl) disulfides 1c and 1d selectively lead to the aromatic arylthiolation in high yields. The Hammett ρ = -8.8 at 25°C for the phenylthiolation in the reactions of 1a is more negative than that (ρ = -7.0 at -30°C) using SbCl5 instead of AlCl3, and the value ρ = -8.0 for the arylthiolation using 1d is less negative than that using 1a. These and the other mechanistic aspects support the arylthiolations via 2.
- Takeuchi, Hiroshi,Suga, Keisuke
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p. 1803 - 1808
(2007/10/03)
-
- Kinetics and mechanism of the aminolysis of thiophenyl methylacetates in acetonitrile
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The aminolysis of Z-thiophenyl methylacetates (C2H5C(double bond O)SC6H4Z) with X-benzylamines in acetonitrile has been investigated at 45 °C. The reaction is found to proceed by a stepwise mechanism in which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, T±, with possibly a hydrogen-bonded four-center-type transition state. These mechanistic conclusions are drawn based on (i) the large magnitude of βX (= 1.2 to approximately 2.5) and βz (= -0.9 to approximately -1.5), (ii) the normal kinetic isotope effects (kH/kD?1.2) involving deuterated benzylamines (XC6H4CH2ND2), (iii) a large positive ρxz (= 2.4) and (iv) adherence to the reactivity-selectivity principle in all cases. The extremely large βX (βnuc) values can be accounted for by the loss of a strong localized cationic charge on the N atom of benzylamines in the expulsion from the T±. The pKa° (≥10.0) is high due to a large ratio of the expulsion rates of the amine (k-a) to thiophenolate (kb) (k-a/kb) from the T±.
- Oh, Hyuck Keun,Yang, Jin Hee,Cho, In Ho,Lee, Hai Whang,Lee, Ikchoon
-
p. 485 - 490
(2007/10/03)
-
- A rapid and efficient cleavage of organic disulfides to mercaptans using ZrCl4/NaBH4
-
A practical and cheaper reagent system ZrCl/NaBH4 is used for the reductive cleavage of organic disulfides to mercaptans under mild conditions, in excellent yields.
- Purushothama Chayr,Rajaram,Iyengar
-
p. 3905 - 3911
(2007/10/03)
-
- Non-aqueous reduction of aromatic sulfonyl chlorides to thiols using a dichlorodimethylsilane-zinc-dimethylacetamide system
-
A new and efficient method for the non-aqueous reduction of sulfonyl chlorides to affored the corresponding thiols by use of a dichlorodimethylsilane-zinc-dimethylacetamide system was successfully developed. Various aromatic thiols were prepared in high yield by easy operation. Continuous reactions with the above reduction using the prepared thiol were also demonstrated.
- Uchiro, Hiromi,Kobayashi, Susumu
-
p. 3179 - 3182
(2007/10/03)
-
- Structure-Reactivity Correlations in the Aminolysis of Ethyl S-Aryl Thiolcarbonates
-
The reactions of secondary alicyclic amines (saa) with ethyl S-4-X-phenyl thiolcarbonates (X = Cl, H, Me, and MeO) are subjected to a kinetic analysis in water, 25.0°C, ionic strength 0.2 (KCl). By following the leaving groups spectrophotometrically (260-270 nm), under amine excess, pseudo-first-order rate coefficients (kobsd) are obtained. Plots of kobsd against free-amine concentration at constant pH are linear, with slope (kN) independent of pH. The Broensted-type plots (log kN against amine pKa) are linear for the aminolysis of the four substrates, with slopes βN = 0.7-0.8. The magnitudes of the slopes are consistent with a stepwise mechanism through a zwitterionic tetrahedral intermediate (T±) whose breakdown to products is rate-determining (k2 step). This mechanism is simpler than that for the same aminolysis of the corresponding ethyl S-aryl dithiocarbonates, which includes proton transfer from T± to the amine (k3 step), due to the fact that for the title reactions k2 > k3[amine]. With the results of the present work and those for the reactions of saa with ethyl S-4-nitrophenyl thiolcarbonate, a dual parametric equation is deduced for kN as a function of amine and leaving group basicity, with both βN and βlg = 0.8. Another dual parametric equation is deduced from literature data for the pyridinolysis of ethyl S-aryl thiolcarbonates. Comparison of both multiparametric expressions shows that pyridines are more reactive than isobasic saa toward thiolcarbonates when breakdown of T± to products is rate-limiting.
- Castro, Enrique A.,Cubillos, Maria,Santos, Jose G.
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p. 6342 - 6346
(2007/10/03)
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- Oxidative cleavage of S-Arylmercaptoacetic acids by pyridinium chlorochromate: Kinetic and correlation analysis
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Kinetics of oxidation of 24 S-Arylmercaptoacetic acids (SAMA) by pyridinium chlorochromate (PCC) have been studied in acid medium. The product of oxidation is the corresponding thiophenol. The rate data of meta- and para-substituted acids have been correlated well with σI, σ°R values and the meta-compounds correlate well with F,R values. The reaction constants are negative and of smaller magnitudes. Further, the ortho-substituted acids show a good correlation with triparametric equation involving Taft's σI and σ°R and charton's steric parameter v. There is no considerable steric contribution to the total orthosubstituent effect. Based on these observations, the mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
- Kabilan,Girija,Rajagopal
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p. 683 - 688
(2007/10/03)
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- Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 13.1 Extrusion of Ph3P from sulfinyl ylides and reactivity of the resulting sulfinyl carbenes
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Six α-sulfinyl phosphorus ylides 6 have been prepared and are found upon flash vacuum pyrolysis at 500°C to undergo mainly extrusion of Ph3P to give thioesters, presumably by 1,2-oxygen transfer in the initially formed sulfinyl carbenes; for α-arylsulfinyl ylides loss of Ph3PO to give additional products is also observed.
- Aitken, R. Alan,Drysdale, Martin J.,Ryan, Bruce M.
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p. 3345 - 3348
(2007/10/03)
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- Process for preparing aromatic or heteroaromatic sulfur compound
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The present invention provides a process for preparing an aromatic or heteroaromatic thiol represented by the formula (2), the process comprising hydrolyzing an aromatic or heteroaromatic halogenated methyl sulfide represented by the formula (1) wherein Ar is an aromatic or heteroaromatic ring which has no substituent or which has an optional substituent or substituents, X is a halogen atom, m is an integer of 1 to 3 and n is 1 or 2. According to the present invention, an aromatic or heteroaromatic thiol can be prepared at a commercially low cost and with ease.
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- Structure - reactivity correlation in the reactions of pyrrolidine with O-ethyl S-aryl dithiocarbonates in aqueous ethanol
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The reactions of pyrrolidine with O-ethyl S-(X-phenyl) dithiocarbonates (X = 4-methyl, 4-methoxy, H, 4-chloro, 4-nitro, 2,4-dinitro, and 2,4,6-trinitro) are subjected to a kinetic study in 44 wt% aqueous ethanol, 25.0°C, and ionic strength 0.2 M (maintained with KCl). Pseudo-first-order kinetics are found under amine excess. Linear plots of the pseudo-first-order rate coefficient against concentration of free-base pyrrolidine are obtained for all the reactions, nucleophilic rate coefficient (kN) being the slope of such plots. The Bronsted-type plot (log kN vs. pKa for the leaving group) is linear with slope β1g = -0.2, which is consistent with a mechanism through a tetrahedral intermediate (T±) where its formation is rate determining. The β1g value is very similar to that found in the same reactions in water. There is a great difference in the mechanism of the reactions of O-ethyl S-phenyl dithiocarbonate with pyrrolidine (order one in amine) and piperidine (complex order in amine) in aqueous ethanol, and this is attributed to a greater nucleofugality from T± of piperidine rather than pyrrolidine.
- Castro,Cabrera,Santos
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p. 113 - 117
(2007/10/03)
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- Oxidative Cleavage of S-Arylmercaptoacetic Acids by Sodium Perborate: Kinetic and Correlation Study
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Kinetics of oxidation of twenty six S-arylmercaptoacetic acids (SAMA) (I) by sodium perborate (PB) have been studied in acid medium.The product of oxidation is the corresponding thiophenol.The rate data of meta- and para-substituted acids have been correlated with DSP equations.While the para-compounds correlate well with ?I and ?0R values, the meta-compounds correlate well with ?I and ?-R values.The reaction constants are negative and of smaller magnitudes.Further, the ortho-substituted acids show a good correlation with a triparametric equation involving Taft's ?I and ?0R and Charton's steric parameter ν.There is a considerable steric contribution to the total ortho-substituent effect.Based on these observations, mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
- Kabilan, S.,Pandiarajan, K.,Krishnasamy, K.,Sankar, P.
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p. 443 - 452
(2007/10/02)
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- Structure-Reactivity Relationships in the Aminolysis of O-Ethyl S-Aryl Dithiocarbonates in Aqueous Solution
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The reactions of O-ethyl S-(X-phenyl) diothiocarbonates (X = p-Cl, p-Me, and p-MeO) with a series of secondary alicyclic amines and those of the same substrates and analogous derivatives (X = H, p-NO2, 2,4-(NO2)2 with pyrrolidine are subjected to a kinetic study in water, 25.0 deg C, ionic strength 0.2 M (KCl).The reactions of piperidine and pyrrolidine show second-order kinetics (first order in amine) with the formation of a zwitterionic tetrahedral intermediate (T+/-) as the rate-determining step.The reactions of the other amines exhibit orders in amine differentfrom one, compatible with the presence of an anionic intermediate (T-), resulting from a kinetically important proton transfer from T+/- to the amine.The rate of this proton transfer is faster than that of expulsion of arylthiolate from T+/- (k2) as evidenced by the estimation of these rate coefficients.The rate constants for formation of T+/- (k1) are obtained experimentally, and those for amine expulsion from T+/- (k-1) are estimated.Equations for k1 and k-1 are derived as functions of the basicity of the amine and leaving (aryl thiolate) groups.Comparison of the k-1 and k2 values found in the present reactions with those obtained in the aminolysis of aryl dithioacetates shows that substitution of Me by EtO as the "acyl" group of the zwitterionic tetrahedral intermediate destabilizes this species.
- Castro, Enrique A.,Cubillos, Maria,Ibanez, Fernando,Moraga, Inge,Santos, Jose G.
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p. 5400 - 5404
(2007/10/02)
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- Kinetics and Mechanism of the Acid-Catalysed Hydrolysis of Benzaldehyde Diaryl Thioacetals and of Benzaldehyde S-Aryl, S-Ethyl Acetals in Aqueous Perchloric Acid
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The effects on the rate of hydrolysis of changes in aryl substituents, acid concentration, temperature, and solvent isotope, show that the acid-catalysed hydrolyses of five benzaldehyde diaryl thioacetals and three benzaldehyde S-aryl, S-ethyl acetals in 2-7 mol dm-3 aqueous perchloric acid proceed via essentially A1 mechanisms.The pattern of the substituent effects found for the leaving, and remaining, S-aryl groups is similar to that found previously for leaving and remaining groups in O,O- and O,S-acetals.
- Ali, Muhammad,Satchell, Derek P. N.
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p. 1825 - 1828
(2007/10/02)
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- Kinetics and Mechanism of the Aminolysis of S-Phenyl Thiobenzoates
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Kinetic studies on the nucleophilic substitution reaction of S-phenyl thiobenzoates with anilines have been carried out at 55.0 deg C.Effects of substituents in the nucleophile(X), substrate(Y) and leaving groups(Z) are analyzed in terms of Hammett's and Broensted's coefficients, ρi and βi and cross-interaction constants ρij and βij where i and j denote X, Y or Z.The sign of ρXZ (or βXZ) is positive, and accordingly, the transition state(TS) variations with the substituents are consistent with those predicted by the potential energy surface diagram; the magnitude of ρx(βx) and ρxy decreases with a better leaving group, and that of ρz and βz decreases with a stronger nucleophile leading to an earlier TS, in agreement with a normal Hammond effect.The larger magnitudes of ρXY, ρYZ and βXZ suggest that the reaction proceeds by an associative SN2 mechanism.A greater kH/kD value (1.0) is observed with deuterated aniline nucleophiles for a stronger nucleophile and a better leaving group, supporting the earlier TS proposed on the basis of the cross-interaction constants.The inverse secondary kinetic isotope effects obtained preclude involvement of any four-center TS or base catalysis by aniline.
- Lee, Ikchoon,Shim, Chang Sub,Lee, Hai Whang
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p. 769 - 793
(2007/10/02)
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- 1-[1-aryl-1-hydroxy-2-azolyl-ethyl]-1-aryl-cyclopropane derivatives, and their fungicidal use thereof
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Compounds I STR1 where A equals t-butyl or a large number of (substituted) aromatics; Y equals azolyl; or Y equals --X--R1 where X=oxygen or sulfur and R1 equals (cyclo)alkyl or (heterocyclic) aryl; or Y equals STR2 where R2 equals (cyclo)alkyl, acetyl or aryl; or Y equals --NR3 R4 where R3 /R4 is alkyl; or Y equals several nitrogen-containing heterocyclic rings; Z equals OH, alkylcarbonyloxy, hal, alkoxy or benzyloxy; and the salts thereof are effective antimycotics or fungicides. They are obtained by reaction of II STR3 with (CH3)2 STR4 and further reaction of the compound IV STR5 obtained from this with a nucleophile YM (M=hydrogen or a metal equivalent). The compounds I (where Z=OH) resulting from this can be acylated or alkylated, or converted into I where Z=hal.
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- Rapid and Selective Reduction of Functionalized Aromatic Disulfides with Lithium Tri-tert-butoxyaluminohydride. A Remarkable Steric and Electronic Control. Comparison of Various Hydride Reagents
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Lithium tri-tert-butoxyaluminohydride (LTBA), an exceptionally mild reducing agent in organic synthesis, reduces functionalized aromatic disulfides to the corresponding thiols in quantitative yield.The reaction is rapid (for example, o-tolyl disulfide is reduced to completion in 60 min at 25 deg C) and can tolerate a wide variety of functional groups, such as halogen, nitro, carboxylic acid, and their derivatives.The presence of electron-withdrawing substituents dramatically enhances the rate of reduction (p-chlorophenyl disulfide is quantitatively reduced in 30 s) and electron-releasing substituents diminishes the rate of cleavage.The reaction is sensitive to steric effects (2,4-di-tert-pentylphenyl disulfide underwent 25percent reduction in 24 h).However, such hindered disulfides can be rapidly and quantitatively reduced in refluxing THF.The reaction of LTBA with alkyl disulfides is extremely sluggish.The reaction provides a useful and simple means for the facile and selective reduction of aromatic disulfides where this is required in synthetic operations.
- Krishnamurthy, S.,Aimino, D.
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p. 4458 - 4462
(2007/10/02)
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- REDUCTIVE CLEAVAGE OF SULFUR OF SULFUR-SULFUR BONDS WITH SODIUM HYDROGEN TELLURIDE
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Sodium hydrogen telluride is shown to be an effective reagent for reduction of alkyl, aryl and functionally substituted disulfides to thiols in good yield under mild conditions.Organic thiosulfites (Bunte salt) also give thiols through the corresponding disulfide on reaction with sodium telluride.
- Kong, Fangming,Zhou, Xunjun
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p. 3143 - 3150
(2007/10/02)
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- REDUCTIVE CLEAVAGE OF SYMMETRICAL DISULFIDES WITH HYDRAZINES
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An efficient method for the reductive cleavage of symmetrical disulfides with hydrazines is described.
- Maiti, Samarendra N.,Spevak, Paul,Singh, Maya Prakash,Micetich, Ronald G.,Reddy, A. V. Narender
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p. 575 - 582
(2007/10/02)
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