3581-91-7Relevant articles and documents
Mechanism of formation of sulphur aroma compounds from l-ascorbic acid and l-cysteine during the Maillard reaction
Yu, Ai-Nong,Tan, Zhi-Wei,Wang, Fa-Song
experimental part, p. 1316 - 1323 (2012/06/30)
The sulphur aroma compounds produced from a phosphate-buffered solution (pH 8) of l-cysteine and l-, l-[1-13C] or l-[4-13C] ascorbic acid, heated at 140 ± 2 °C for 2 h, were examined by headspace SPME in combination with GC-MS. MS data indicated that C-1 of l-ascorbic acid was not involved in the formation of sulphur aroma compounds. The sulphur aroma compounds formed by reaction of l-ascorbic acid with l-cysteine mainly contained thiophenes, thiazoles and sulphur-containing alicyclic compounds. Among these compounds, 1-butanethiol, diethyl disulphide, 5-ethyl-2-methylthiazole, cis and trans-3,5-dimethyl-1,2,4-trithiolane, thieno[2,3-b]thiophene, thieno[3,2-b]thiophene, cis and trans-3,5-diethyl-1,2,4-trithiolane, 1,2,5,6-tetrathiocane, 2-ethylthieno[2,3-b]thiophene, 2,4,6-trimethyl-1,3,5- trithiane and cyclic octaatomic sulphur (S8) were formed solely by l-cysteine degradation, and the rest by reaction of l-ascorbic acid degradation products, such as hydroxybutanedione, butanedione, acetaldehyde, acetol, pyruvaldehyde and formaldehyde with l-cysteine or its degradation products, such as H2S and NH3. A new reaction pathway from l-ascorbic acid via its degradation products was proposed.
Reactivity of neutral nitrogen donors in square-planar d8 metal complexes: The system chloro(2,2′:6′,2″-terpyridine)platinum(II) cation with five-membered N-donor heterocycles in methanol
Pitteri, Bruno,Bortoluzzi, Marco
, p. 2698 - 2704 (2008/10/09)
The kinetics of the forward and reverse steps of the reaction [Pt(terpy)Cl]+ + nu ? [Pt(terpy)(nu)]2+ + Cl- (terpy = 2,2′:6′,2″-terpyridine, nu = one of a number of thiazoles, oxazole, isoxazole, imidazole, pyrazole and 3,5-dimethylpyrazole, covering a wide range of basicities) have been studied in methanol at 25 °C. Both forward and reverse reactions obey the usual two-term rate law observed in square-planar substitution. The second-order rate constants for the forward reactions, k2f, show a slight dependence upon the basicity of the entering nu, while the steric hindrance due to the presence of one methyl group in the α position to the nitrogen markedly decreases the reactivity. The second-order rate constants for the reverse reactions, k2r, are very sensitive to the nature of the leaving group and a plot of log k2r against the pKa of the conjugate acids of the unhindered five-membered N-donors is linear with a slope of -0.51. The results are compared with data from the literature regarding a series of pyridines reacting with the [Pt(terpy)Cl]+ cation under the same experimental conditions. Both in the forward and in the reverse reaction, the reactivity depends not only upon the ligand basicity but also upon the nature of the nucleophile in the order: (thiazoles, oxazole, isoxazole, imidazole, pyrazoles) > pyridines for the entry of N-donors and on the contrary for the displacement by Cl-. Steric retardation, due to the presence of a methyl group in the α position to the nitrogen, is remarkably lower for five-membered N-donors if compared to pyridines both in the forward and in the reverse reaction.
Thiazole, imidazole and oxazole compounds and treatments of disorders associated with protein aging
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, (2008/06/13)
Provided are, among other things, compounds of formula I or IA, . Also provided are methods of treatment with such compounds.
Method for treating glaucoma IIB
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, (2008/06/13)
Provided is a method of decreasing intraocular pressure or improving ocular accommodation in an animal, including a human, comprising administering an intraocular pressure decreasing amount or ocular accommodation improving amount of a compound of the formula I or IA, wherein J is oxygen, sulfur, or N—Rd.
Heterocyclic volatiles formed by heating cysteine or hydrogen sulfide with 4-hydroxy-5-methyl-3(2H)-furanone at pH 6.5
Whitfield, Frank B.,Mottram, Donald S.
, p. 816 - 822 (2007/10/03)
The reaction of 4-hydroxy-5-methyl-3(2H)-furanone (HMF) with cysteine or hydrogen sulfide at pH 6.5 for 60 min at 140°C produced complex mixtures of volatile compounds, the majority of these containing either sulfur or nitrogen. Of the 68 compounds detect
1,2,3-Benzothiadiazole derivatives
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, (2008/06/13)
Novel 1,2,3-benzothiadiazole derivatives of the formula STR1 in which Het has the meanings set forth in the specification, and addition products thereof with an acid or metal salt are very effective for the control of undesired microorganisms. Novel intermediates of the formulae STR2 in which Het1 and R5 have the meanings given in the specification.
Chloropyridylcarbonyl derivatives
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, (2008/06/13)
Novel chloropyridylcarbonyl derivatives of the formula STR1 in which Het is STR2 n is 1 or 2, R1 is hydrogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C3-6 alkynyl, optionally substituted phenyl or optionally substituted pyrimidinyl, and R2 and R3, independently of each other, are hydrogen or C1-4 alkyl, and acid addition salts and metal salt complexes thereof, are outstandingly active as microbicides.
Deamination of 2-aminothiazoles and 3-amino-1,2,4-triazines with nitric oxide in the presence of a catalytic amount of oxygen
Itoh, Takashi,Matsuya, Yuji,Nagata, Kazuhiro,Ohsawa, Akio
, p. 1547 - 1549 (2007/10/03)
2-Aminothiazoles, 2-aminobenzazoles, and 3-amino-1,2,4-triazines were deaminated using nitric oxide (NO) in the presence of a catalytic amount of oxygen to afford corresponding unsubstituted heterocycles in good yields.
Reactivity of Heterocyclic Nitrogen Donors in Systems containing the Tetrachloroaurate(III) Anion
Canovese, Luciano,Cattalini, Lucio,Tomaselli, Michele,Tobe, Martin L.
, p. 307 - 314 (2007/10/02)
A series of gold(III) complexes of the type has been prepared and characterized (L = oxazole, benzoxazole, thiazole, their benzo and methyl-substituted derivatives, or 2-methylbenzoselenazole).The five-membered N.O-, N,S- and N,Se-heterocyclic bases are all bound to Au(III) through nitrogen.The kinetics of the displacement of L by chloride to give (1-) has been studied in methanol-water (95:5. v/v) at 25.0 deg C and I = 0.20 mol dm-3 (LiClO4).The equilibrium constants for the reversible processes have also been determined.The reactions of the corresponding pyridine, 4-chloro-, 4-cyano- and 2,6-bis(chloromethyl)-pyridine complexes have also been reexamined under the same conditions.The equlibrium constants, K2, depend upon the basicity of the nitrogen in the ligands and points for all ligands, irrespective of ring size and composition, lie roughly on the same log K2 versus pKa curve.There is no significant systematic steric effect on the equilibrium constants of the sort found for the more basic methyl pyridines.The complexes of the five-membered heterocyclic ligands are approximately ten times less reactive than those of the six-membered N-heterocycles of comparable basicity and exhibit steric retardation from ortho-methyl substituents.The nucleophilicities of these ligands have been calculated and five-membered N,O- and N,S-heterocycles are considerably less reactive than six-membered N-heterocycles of similar basicity.
A NEW VAPOR-PHASE SYNTHESIS OF THIAZOLES
Amato, Joseph S.,Karady, Sandor,Phillips, Brian T.,Weinstock, Leonard M.
, p. 1947 - 1949 (2007/10/02)
The vapor-phase reaction of imines with sulfur dioxide to produce thiazoles has been studied at 450 - 500 deg C.Of the imines investigated acetone methyl imine was the most studied which produced 4-methylthiazole in 70percent yield.
