- Kinetics and Mechanism of the Oxidation of Thiourea by Bromate in Acidic Solution
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The reaction between bromate and thiourea has been studied in acidic medium.The stoichiometry of the reaction in excess thiourea is 4BrO3- + 3SC(NH2)2 + 3H20 -> 3SO42- + 3OC(NH2)2 + 4Br- + 6H+; in excess bromate the stoichiometry is 8BrO3- + 5SC(NH2)2 + H2O -> 5SO42- + 5OC(NH2)2 + 4Br2 + 2H+.No bromine is formed in excess thiourea.In excess bromate the reaction displays an initial induction period.At the end of the induction period, the redox potential of the reaction mixture rises sharply, sulfate appears (signaled by precipitation of BaSO4 when BaCl2 is initially added), and a yellow coloration (due to bromine) is first noticeable.Consequently, bromine is not formed until all thiourea is consumed.A 14-step mechanism is proposed and used to simulate the observed kinetics.The rate-determining step for bromine appearance is formation of HOBr from the BrO3--Br- reaction.The oxidation of thiourea proceeds via oxygen additions on sulfur, successively forming HOSC(NH)NH2, HO2SC(NH)NH2, HO3SC(NH)NH2, and SO42-.The mechanism requires that cleavage of the X-C bond to form urea and SO42- occur at the sulfonic acid level and not before, in agreement with experimental observation.
- Simoyi, Reuben H.,Epstein, Irving R.,Kustin, Kenneth
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- New and surprising experimental results from the oxidation of sulfinic and sulfonic acids
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Thiourea, (H2N)2C=S, aminoiminomethanesulfinic acid, H2N(HN=)CSO2H (AIMSA), and aminoiminomethanesulfonic acid, H2N(HN=)CSO3H (AIMSOA) are all oxidized by mild oxidizing agents to a sulfate and an organic residue. AIMSA and AIMSOA are the postulated intermediates in the oxidation pathway of thiourea to sulfate. The oxidation of AIMSOA is accompanied by a cleavage of the C-S bond to form sulfate. Surprisingly, freshly prepared solutions of AIMSOA are oxidized by the common oxidants (oxyhalogens and halogens) at rates that are much slower than oxidation rates of AIMSA by the same oxidants. These results seem to suggest that AIMSOA may be structurally different from AIMSA and that the decomposition of AIMSOA to HSO3- is the prerequisite to its oxidation. The oxidation pathway of AIMSA to SO42- also proceeds through the formation of HSO3- and not predominantly through AIMSOA.
- Makarov, Sergei V.,Mundoma, Claudius,Penn, John H.,Svarovsky, Serge A.,Simoyi, Reuben H.
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- Tandem mass tags: A novel quantification strategy for comparative analysis of complex protein mixtures by MS/MS
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A novel MS/MS-based analysis strategy using isotopomer labels, referred to as "tandem mass tags" (TMTs), for the accurate quantification of peptides and proteins is described. The new tags are designed to ensure that identical peptides labeled with different TMTs exactly comigrate in all separations. The tags require novel methods of quantification analysis using tandem mass spectrometry. The new tags and analysis methods allow peptides from different samples to be identified by their relative abundance with greater ease and accuracy than other methods. The new TMTs permit simultaneous determination of both the identity and relative abundances of peptide pairs using a collision induced dissociation (CID)-based analysis method. Relative abundance measurements made in the MS/MS mode using the new tags are accurate and sensitive. Compared to MS-mode measurements, a very high signal-to-noise ratio is achieved with MS/MS based detection. The new tags should be applicable to a wide variety of peptide isolation methods.
- Thompson, Andrew,Schaefer, Juergen,Kuhn, Karsten,Kienle, Stefan,Schwarz, Josef,Schmidt, Guenter,Neumann, Thomas,Hamon, Christian
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- Oxyhalogen-Sulfur Chemistry: Oligooscillations in the Formamidinesulfinic Acid-Chlorite Reaction
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The reaction between chlorite and formamidinesulfinic acid has been studied in perchloric acid between pH 1 and 3.The stoichiometry of the reaction in excess chlorite is HO2SC(NH)NH2 + ClO2(-) + H2O --> SO4(2-) + OC(NH2)2 + Cl(-) + 2H(+) (A), while the stoichiometry in excess formamidinesulfinic acid is a mixture of (A) and (B): 2HO2SC(NH)NH2 + ClO2(-) --> 2HO3SC(NH)NH2 + Cl(-) (B).In excess chlorite at the end of the oxidation of formamidinesulfinic acid ClO2 is formed from the reaction 2ClO2(-) + HOCl + H(+) --> 2ClO2 + Cl(-) + H2O.The formation of ClO2 shows some oligooscillatory behavior in which, even in excess formamidinesulfinic acid, there is transient formation of ClO2.The reaction is autocatalytic in HOCl via the asymmetric Cl2O2 intermediate.The dynamics of the reaction are explained via a mechanism which is derived from the one used for the chlorite-thiourea reaction.
- Jones, Juan B.,Chinake, Cordelia R.,Simoyi, Reuben H.
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- Selective oxidation of thiourea with H2O2 catalyzed by [RuIII(edta)(H2O)]-: Kinetic and mechanistic studies
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Reported here is the first example of a ruthenium complex, [Ru III(edta)(H2O)]- (edta4- = ethylenediaminetetraacetate), that catalyzes the oxidation of thiourea (TU) in the presence of H2O2. The kinetics and mechanism of this reaction were investigated in detail by using rapid-scan spectrophotometry as a function of both the hydrogen peroxide and thiourea concentrations at pH 4.9 and 25 °C. Spectral analyses and kinetic data clearly support a catalytic process in which hydrogen peroxide reacts directly with thiourea coordinated to the RuIII(edta) complex. HPLC product analyses revealed the formation of formamidine disulfide (TU2) as a major product at the end of the catalytic process, however, formation of other products like thiourea dioxide (TUO2), thiourea dioxide (TUO3) and sulfate was also observed after longer reaction times. Catalytic intermediates such as [Ru III(edta)(OOH)]2- and [RuV(edta)(O)] - were evidently found to be non-reactive in catalyzing the oxidation of thiourea by H2O2 under the specified conditions. The Royal Society of Chemistry 2013.
- Chatterjee, Debabrata,Rothbart, Sabine,Van Eldik, Rudi
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- Kinetic study on hydrolysis and oxidation of formamidine disulfide in acidic solutions
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Hydrolysis and oxidation of formamidine disulfide in acidic medium were investigated using high-performance liquid chromatography (HPLC) and mass spectrometry (MS) at 25 °C. By controlling the slow reaction rate and choosing appropriate mobile phase, HPLC provides the unique advantages over other methods (UV-Vis, chemical separation) in species tracking and kinetic study. In addition to thiourea and formamidine sulfinic acid, two unreported products were also detected in the hydrolysis reaction. Mass spectrometry measurement indicates these two products to be formamidine sulfenic acid and thiocyanogen with mass weights of 92.28 and 116.36, respectively. In the oxidation of formamidine disulfide by hydrogen peroxide, besides thiourea, formamidine sulfenic acid, formamidine sulfinic acid, thiocyanogen and urea, formamidine sulfonic acid and sulfate could be detected. The oxidation reaction was found to be first order in both formamidine disulfide and hydrogen peroxide. The rate constants of hydrolysis and oxidation reactions were determined in the pH range of 1.5-3.0. It was found both rate constants are increased with the increasing of pH. Experimental curves of different species can be effectively simulated via a mechanism scheme for formamidine disulfide oxidation, including hydrolysis equilibrium of formamidine disulfide and irreversible hydrolysis of formamidine sulfenic acid.
- Hu, Ying,Feng, Jiamin,Li, Yanwei,Sun, Yanyan,Xu, Li,Zhao, Yuemin,Gao, Qingyu
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- A facile synthesis of aminoiminomethanesulfonic acid
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Aminoiminomethanesulfonic acid was conveniently obtained by oxidation of aminoiminomethanesulfinic acid with H2O2 in a high yield and good purity.
- Pan,Pan
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- MONOSUBSTITUTED GUANIDINES FROM PRIMARY AMINES AND AMINOIMINOMETHANESULFONIC ACID
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Aminoiminomethanesulfonic acid, H2N-C(=NH)SO3H, converts primary amines to the corresponding guanidine derivatives at 20 deg C.This crystalline reagent is readily prepared by the peracetic acid oxidation of formamidinesulfinic acid, H2N-C(=NH)SO2H.The synthesis is illustrated by a representative group of simple monosubstituted guanidines shown in Table I.
- Kim, Keekyung,Lin, Yi-Tsong,Mosher, Harry S.
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- Synthetic method for organic intermediate formamidine sulfinic acid
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The invention discloses a synthetic method for the organic intermediate formamidine sulfinic acid. The synthetic method comprises the following steps: adding 1-chloro-1-sulfo-diaminomethane and a potassium bromide solution into a reaction vessel, controlling a stirring speed to be 210-230 rpm, controlling a solution temperature to be 15-21 DEG C, adding a diethylene glycol diacetate solution and N-bromoacetamide and continuing a reaction for 90-120 min; and adding nickel nitrate powder, controlling a stirring speed to be 310-330 rpm, continuing a reaction for 2-4 h, lowering a temperature to 5-9 DEG C, then carrying out standing for 20-40 min, adding a sodium sulfate solution, subjecting the solution to layering to separate an oil layer, carrying out washing with a nitroethane solution for30-50 min, then carrying out recrystallization in a hexanediol solution, and carrying out dehydration with a dehydrating agent so as to obtain the finished formamidine sulfinic acid.
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Paragraph 0023-0026
(2018/07/30)
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- Ligustrazine derivatives. Part 6: Design, synthesis and evaluation of novel ligustrazinyl acylguanidine derivatives as potential cardiovascular agents
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A series of novel Ligustrazinyl acylguanidines was designed, synthesized and evaluated for their protective effect on injured vascular endothelial cell (ECV-304). The preliminary results demonstrated that some compounds possessed more potent activities than that of Ligustrazine in stimulating replication of the injured endothelial cell. Among the active compounds, compounds 8b, 8f and 8l displayed remarkable antioxidative activity with low EC50 values of 0.097, 0.059 and 0.094 mM, respectively. Structure-activity relationships were briefly discussed.
- Li, Zhenyu,Yu, Fang,Zhan, Peng,Shen, Yuemao,Liu, Xinyong,Cui, Lei,Wang, Shouxun
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p. 928 - 933,6
(2020/08/31)
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- Efficient synthesis of 2-arylamino-2-imidazolines and 2-aminobenzimidazoles with aminoiminomethanesulfonic acid derivatives
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A highly efficient synthesis of 2-arylamino-2-imidazolines and 2-aminobenzimidazoles from aminoiminomethanesulfonic acid derivatives is described. The method is simple and practical, generating imidazoline and benzimidazoline derivatives in excellent isolated yields.
- Mohanazadeh, Farajollah,Nami, Navabe,Hosseini, Samine Sadat
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experimental part
p. 1055 - 1058
(2012/01/04)
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- Methods for purifying radiolabelled compounds
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One aspect of the present invention relates to a method of purifying radiolabelled compounds comprising a) loading onto a fluorous polymer a radiolabelled compound precursor comprising a fluoroalkyl tin moiety; b) reacting the radiolabelled compound precursor with a radiolabel delivering compound to give a radiolabelled compound, wherein the fluoroalkyl tin moiety is replaced by a radiolabel; and c) eluting the radiolabelled compound from the fluorous polymer.
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Page/Page column 15; 22
(2008/06/13)
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- 7-Azabicycloheptane Carboxylic Acid: A Proline Replacement in a Boroarginine Thrombin Inhibitor
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(Matrix Presented) The synthesis of thrombin inhibitor 3, which incorporates conformationally constrained 7-azabicycloheptane carboxylic acid (1) as a proline replacement, is described. The inhibition constant (Ki(thrombin) = 2.9 nM) indicates
- Han, Wei,Pelletier, Jeffrey C.,Mersinger, Lawrence J.,Kettner, Charles A.,Hodge, Nicholas C.
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p. 1875 - 1877
(2008/02/11)
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- Amine and amidine containing compounds as weight reducing agents
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Use of amine and amidine containing compounds of formula (I) such as galegine and related substituted amine and amidine containing compounds as agents for reducing weight in mammals, pharmaceutical formulations containing a compound of formula (I) and methods of attaining weight reduction in mammals.
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- Synthesis of Amido-ureas and the Nature of Caracasanamide, the Hypotensive Principle of Verbesina caracasana
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Syntheses of the (E)-1 and (Z)-2 forms of 1-(3-methylbut-2-enyl)-3-(4-butyl)urea, proposed structures for the natural hypotensive caracasanamide, have been carried out.The compounds were found not to be identical wit
- Crombie, Leslie,Jarrett, Sandra R. M.
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p. 3179 - 3184
(2007/10/02)
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- A Facile Conversion of Amino Acids to Guanidino Acids
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The conversion of amino acids to guanidino acids by the action of aminoiminomethanesulfonic acids (2a-c) is reported.Compounds 2a-c were synthesized by peracetic acid oxidation of the corresponding thioureas.
- Miller, Audrey E.,Bischoff, Judith J.
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p. 777 - 779
(2007/10/02)
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