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1.
Reemtsma T 《Rapid communications in mass spectrometry : RCM》2000,14(17):1612-1618
A method was developed for the analysis of 2-substituted benzothiazoles from wastewaters by reversed-phase liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). While benzothiazole (BT), 2-amino- (ABT), 2-methyl-, 2-thiocyanomethylthio- and 2-methylthiobenzothiazole were separated with a methanol gradient acidified with formic acid and detected in the positive mode, 2-mercapto- and 2-hydroxybenzothiazole (OHBT) as well as benzothiazole-2-sulfonic acid (BTSA) were separated with the addition of ammonium acetate and detected in the negative ion mode. Detection limits range from 10 ng L(-1) for ABT to 200 ng L(-1) for OHBT after direct injection of 100 μL sample volumes, while BT requires 2.5 μg L(-1). The method is, thus, suitable for direct analysis in wastewaters. Its application to tannery effluent samples revealed, that, besides a 90-95% elimination of total benzothiazoles, the concentration of OHBT and BTSA increased during the biological treatment. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
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T. I. Mukhanova L. M. Alekseeva A. S. Shashkov V. G. Granik 《Chemistry of Heterocyclic Compounds》2005,41(2):221-227
Treatment of the enamines of acetylacetone and benzoylacetone with 2-methyl-4,7-dioxobenzothiazole under Nenitzescu reaction conditions gave furo[2,3-e]benzothiazoles (in acetic acid) and pyrrolo[2,3-e]benzothiazoles (in nitromethane). Using enamines of acetoacetic ester gave exclusively pyrrolo[2,3-e]benzothiazoles.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 252–258, February, 2005. 相似文献
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A convenient and efficient strategy for the synthesis of 2-acyl benzothiazoles/thiazoles has been developed. The treatment of benzothiazole/thiazole with allylic Grignard reagents readily generates the corresponding 2-Grignard reagents, which is followed by a reaction with N,N'-carbonyldiimidazole activated carboxylic acids to afford various 2-acyl benzothiazoles/thiazoles products. The synthetic method is applicable to a wide array of carboxylic acids and allows easy access to 2-acyl benzothiazoles/thiazoles with considerable yields under mild reaction conditions. 相似文献
5.
Z Yang X Chen S Wang J Liu K Xie A Wang Z Tan 《The Journal of organic chemistry》2012,77(16):7086-7091
Nontransition metal-catalyzed synthesis of 2-aryl benzothiazoles was achieved through K(2)S(2)O(8)-mediated oxidative condensation of benzothiazoles with aryl aldehydes. The same transformation can also be effected when the aryl aldehydes were replaced with phenylglyoxylic acids. 相似文献
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An efficient and practical method for the construction of 2-aryl- and 2-alkyl-substituted benzothiazoles via a copper-catalyzed redox condensation process between benzothiazoles and aldehydes or benzylic alcohols has been developed. The reaction proceeded under mild reaction conditions using environmentally benign tert-butyl hydroperoxide (TBHP) as the oxidant. A reaction mechanism involving the ring-opening of benzothiazoles initiated by the attack of acyl radical on the thiazole ring and intramolecular condensation is proposed based on the isolation of an anilide disulfide intermediate. 相似文献
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A method was developed for the determination of benzothiazoles from municipal wastewater, which may originate from their use as corrosion inhibitors, vulcanization accelerators or fungicides. Extraction is performed by SPE using a polymeric sorbent, followed by LC-MS analysis with electrospray ionization. Due to the diversity of the analytes, two LC-MS runs are required: 2-aminobenzothiazole, benzothiazole and 2-methylthiobenzothiazole are detected in the positive ion mode, while benzothiazole-2-sulfonic acid (BTSA), 2-mercaptobenzothiazole and 2-hydroxybenzothiazole are determined in the negative ion mode. Limits of quantification range from 20 to 200 ng/L in treated wastewater. Reliable quantification with R.S.D.s below 25% is achieved by standard addition in a limited number of samples of each sample series. A significant reduction of matrix effects in positive electrospray ionization is achieved by reducing the flow directed into the ESI-interface. When applied to untreated municipal wastewater most analytes were found at concentrations in the high ng/L- to low microg/L-range with the most polar BTSA being the dominant compound of this class. Removal of benzothiazoles in biological wastewater treatment appears to be limited. 相似文献
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《Tetrahedron letters》2019,60(24):1587-1591
A peroxide-mediated protocol for the synthesis of 2-substituted benzothiazoles was developed, starting from bis(o-aminophenyl) disulfides and primary alcohols. Eleven differently 2-substituted benzothiazoles were prepared in moderate to excellent yields using di-tert-butyl peroxide (DTBP) as an oxidant. 相似文献
11.
Dr. Chunping Dong Yumei Wang Shiyu Chen Yue Zhang Prof. Cheli Wang Prof. Jian Li Dr. Yongsheng Zhou 《European journal of organic chemistry》2023,26(29):e202300194
Benzyl amines were deaminated for the olefination of methyl N-heteroarenes such as quinolines, benzothiazoles, and quinoxalines catalyzed by 4,6-dihydroxysalicylic acid with only 1 mol % catalyst loading. A wide range of N-heteroaryl stilbenoids were synthesized in yields of 42 to 96 % using oxygen (1 atm) as the sole oxidant. 4,6-dihydroxysalicylic acid not only behaves as an organocatalyst for the oxidation of benzyl amines to the imine intermediates, but also provides an acidic reaction condition for the olefinations. Gram scale reaction and the synthesis of two pharmaceutically relevant conjugated olefins were also successful using this methodology. 相似文献
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A convenient synthesis of substituted benzothiazoles from 2-bromoanilides has been accomplished. The various 2-bromoanilides were reacted with an alkyl thiolate in high yields using a palladium catalyst. The resulting sulfides were easily converted to the corresponding benzothiazoles via the simultaneous generation of thiols and condensation under basic or acidic conditions. 相似文献
13.
The mass spectra of nineteen substituted benzothiazoles have been recorded and the identity of the various ions in the mass spectra has been established by high resulution (accurate) mass measurement. Deuterium labelling has been used to elucidate the fragmentation processes of these compounds. The parent compound of the series, benzothiazole, exhibits the loss of hydrogen cyanide and carbon monosulphide from the parent ion as the most important decomposition pathways. The hydrogen atom concerned in the loss of hydrogen cyanide is shown to originate from the 2-position of benzothiazole, while in 2-substituted benzothiazoles, different mechanisms are apparent for the loss of hydrogen cyanide, and these are clarified by deuterium labelling. Some substituted benzothiazoles can lose sulphur from their molecular ions, a process which does not occur in benzothiazole itself. The substituted benzothiazoles undergo many other types of fragmentations, in some cases retaining the substituent, and in other cases losing it prior to collapse of the thiazole ring. 相似文献
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Liquid-phase synthesis of 2-substituted benzimidazoles, benzoxazoles and benzothiazoles 总被引:1,自引:0,他引:1
A novel acid fluoride for use in the liquid-phase synthesis of substituted benzimidazoles, benzoxazoles and benzothiazoles was developed. Its synthetic utility is exemplified by a structurally diverse set of aromatic heterocycles. Final cleavage is achieved by treatment with sodium methoxide in methanol for 12 h. The corresponding benzimidazoles, benzoxazoles and benzothiazoles were obtained in good isolated yields (22-62%, four steps). 相似文献
15.
Zhao Yang Renhe Hu Xiaotong Li Xin Wang Ren Gu Shiqing Han 《Tetrahedron letters》2017,58(24):2366-2369
An efficient one-pot three-component reaction of 2-iodoanilines, benzyl chlorides and elemental sulfur to form 2-substituted benzothiazoles in satisfactory yields (up to 98%) has been described. The reaction tolerated a wide range of functional groups on the aromatic ring. And heterocycle methylene chlorides substrates were also found to be compatible. 相似文献
16.
V. M. Cherkasov T. A. Dashevskaya L. I. Baranova 《Chemistry of Heterocyclic Compounds》1969,5(1):127-128
The reaction of aryl isothiocyanates with the N,N-dichloroamides of arenesulfonic acids and with the morpholide of sulfamic acid has been studied. Instead of the expected products of the oxidative imination of the aryl isothiocyanates, 2-(arylsulfonylamino)benzothiazoles and 2-(morpholinosulfonylamino)benzothiazoles, respectively, were obtained. 相似文献
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A number of 2- and 2,5-perfluoroalkyl and perfluoroalkylether substituted benzoxazoles and benzothiazoles have been prepared. Their relative hydrolytic stability has been examined. In all cases the benzothiazoles were more stable that the benzoxazoles. Substituents in the 2-position offering steric hindrance improve hydrolytic stability. 相似文献
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A novel solvent-free and catalyst-free synthesis of benzothiazoles from 2-chloronitrobenzene, elemental sulfur, and aliphatic amine has been developed. The reaction tolerated a wide range of functionalities, and various benzothiazoles were synthesized in moderate to good yields in the absence of external oxidant or reductant. 相似文献
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Methanesulfonic acid/SiO2 (1 mL/0.3 g) was found to be as an expeditious mixture in the synthesis of 2-substituted aromatic and aliphatic benzothiazoles at 140 °C using carboxylic acids. After a simple workup, benzothiazoles were obtained in good yields. Simplicity, use of widely available and diverse carboxylic acids, and easy handling of the reaction conditions are among the benefits of the method. 相似文献
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Three in one: Copper-catalyzed three-component reactions, involving 2-iodoanilines, aldehydes, and sulfur powder, afford 2-phenylbenzothiazoles in water. A variety of 2-substituted benzothiazoles can be obtained in good to excellent yields of up to 96?% (see scheme). 相似文献