2,5-二苯腙基-1,3,4-噻二唑类化合物的合成及抗腐蚀性能研究

以2,5-二巯基-1,3,4-噻二唑为原料, 与水合肼反应制得2,5-二肼基-1,3,4-噻二唑, 再将其与取代苯甲醛缩合, 得到了6种新的2,5-二苯腙基-1,3,4-噻二唑类化合物, 其结构经元素分析、红外、¹H NMR及质谱等方法所证实. 6种噻二唑衍生物对喷气燃料银片腐蚀有一定的抑制作用.     

Syntheses of arylsulfonyl-1,3,4-thiadiazoles

Reaction of sodium arylsulfinate with 2-aryl-5-chloro-1,3,4-thiadiazole gave 2-aryl-5-arylsulfonyl-1,3,4-thiadiazole (3) in good yield. Starting from readily available 2-amino-5-benzylmercapto-1,3,4-thiadiazole compound 7 was obtained in three steps in moderate yield. Reaction of compound 7 with sodium arylsulfinate afforded 2,5-diarylsulfonyl-1,3,4-thiadiazole ( 11 ). Oxidation of compound 10 with hydrogen peroxide in acetic acid gave 2-arylsulfonyl-5-benzylsulfonyI-1,3,4-thiadiazole ( 12 ), in high yield.     

FT-Raman spectroscopy of the reaction of polybutadiene with mercapto-thiadiazoles

Mercapto-thiadiazoles having potential anti-wear behaviour are reacted with polymers with existing viscosity index-improving properties in order to produce materials which may find a use as multifunctional lubricant additives. 2,5-Dimercapto-1,3,4-thiadiazole, 2-amino-5-mercapto-1,3,4-thiadiazole and 2-methyl-5-mercapto-1,3,4-thiadiadiazole were reacted with low MW polybutadiene containing vinyl-1,2, cis-1,4 and trans-1,4 (C=C) groups. The reactions were monitored using FT-Raman spectroscopy in order to determine quantitatively the consumption of the individual structural units when reacted with thiadiazoles. 2,5-Dimercapto-1,3,4-thiadiazole reacted readily with the polybutadiene, achieving 80% reaction within a few hours. The thiadiazole reacted selectively with the order of addition being cis>vinyl>trans. 2-Amino-5-mercapto-1,3,4-thiadiazole and 2-methyl-5-mercapto-1,3,4-thiadiazole were found to react more slowly and hence to a lesser extent (40 and 25%, respectively) over a similar time scale.     

Preparation and properties of new wholly aromatic polyesters containing a terphenyl analogue of 1,3,4-thiadiazole in the main chain

Novel wholly aromatic polyesters 8 containing a terphenyl analogue of 1,3,4-thiadiazole (2,5-diphenyl-1,3,4-thiadiazole) in the main chain were synthesized by high-temperature solution polycondensation of a diacyl chloride derivative of 2,5-diphenyl-1,3,4-thiadiazole 6 with four hydroquinones 7 in 1-chloronaphthalene. These polymers 8 are insoluble in most organic solvents and decompose very rapidly above 400°C in air without showing thermotropic liquid crystalline melts.     

Preparation of halomethyl-1,3,4-thiadiazoles. Conversion to 2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole,an important antimicrobial agent

A new route for the synthesis of 2-amino-5-(l-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole ( 1 ) is described. This route was based upon the preparation of 2-amino-5-halomethyl-1,3,4-thiadiazoles by condensation of haloacetic acids with thiosemicarbazide. One of these intermediates, 2-acetamido-5-dichloromethyl-1,3,4-thiadiazole ( 4 ), was hydrolyzed to the corresponding 5-amino-2-carboxaldehyde 6 , which was trapped as its oxime 5 . 5-Acetamido-1,3,4-thiadiazole-2-carbonitrile ( 7 ), formed upon dehydration of 5 , was then converted into 2-amino-5-(2-imidazolyl)-1,3,4-thiadiazole ( 11 ) by a route based on the Pinner amidine synthesis. Methylation and nitration of the imidazole moiety then completed the preparation of 1.     

3,6-二取代苯基-二-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑衍生物的合成

以2,5-二巯基-1,3,4-噻二唑为原料, 与水合肼缩合, 生成2,5-二肼基-1,3,4-噻二唑. 2,5-二肼基-1,3,4-噻二唑与苯甲酰氯反应生成2,5-二酰肼基-1,3,4-噻二唑, 以POCl₃为环合剂环合酰肼基-1,3,4-噻二唑, 合成3,6-二取代苯基- 二-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑衍生物, 合成的新化合物的结构通过元素分析、红外光谱、核磁共振氢谱和质谱予以证实, 并提出了环化反应机理.     

A new route to 1,2,4- triazoles and 1,3,4- thiadiazoles from 1-acylbithiourea

The intramolecular cyclization of 1- acylbithiourea 1 gave 1,2,4-triazole 2 and 1,3,4-thiadiazole 3 . The reaction of 1 with p-toluenesulfonyl chloride in the presence of trithylamine afforded 3 . Treatment of 1 with methyl iodide in the absence of any base yielded 2-methylthio-1,3,4-thiadiazole 10 and 2-imino- 1,3,4-thiadiazoline 12 .     

N-H?S hydrogen bonding in 2-mercapto-5-methyl-1,3,4-thiadiazole. Synthesis and crystal structures of mercapto functionalised 1,3,4-thiadiazoles

The synthesis and crystal structures of three mercapto functionalised 1,3,4-thiadiazoles and the crystal structure of 2-mercapto-5-methyl-1,3,4-thiadiazole are described. In the solid state, 2-mercapto-5-methyl-1,3,4-thiadiazole 1 forms a thioamide tautomer as shown by FTIR and Raman spectroscopy as well as X-ray crystallography and as theoretically predicted. The molecules are connected to form chains via N-H?S hydrogen bonds with N?S=328.3 pm. Bis(2-methyl-1,3,4-thiadiazolyl)-5,5′-disulfide 2, the disulfide of 1, as well as 2-(tert-butyldithio)-5-methyl-1,3,4-thiadiazole 3 and 2,5-bis(tert-butyldithio)-1,3,4-thiadiazole 4 have been synthesised and characterised by vibrational spectroscopy and X-ray diffraction.     

Chemoselective one-pot synthesis of 2-phenylamino-5-alkylthio-1,3,4-thiadiazole derivatives from phenylthiosemicarbazide and CS2

A novel and fairly efficient chemoselective one-pot method has been developed for the synthesis of both 2-phenylamino-5-alkylthio-1,3,4-thiadiazole and bis-(2-phenylamino-5-alkylthio-)1,3,4-thiadiazole derivatives from phenylthiosemicarbazide and CS₂.     

Synthesis and properties of diaminothiadiazoles

Refined synthetic procedure for preparation of 3,5-diamino-1,2,4-thiadiazole and 2,5-diamino-1,3,4-thiadiazole based on the reaction of dithiourea or amidinothiourea with hydrogen peroxide is developed. The optimal reagents ratio was found, and monitoring methods were developed. It resulted in the increase of the target product yield and in a shorter reaction time. On the basis of 2,5-diamino-1,3,4-thiadiazole the alkylsubstituted 1,3,4-diaminothiadiazolidines were synthesized. The compounds prepared were characterized by the elemental analysis data, the IR, ¹H NMR, and electronic spectra, and also by mass spectrometry.     

Solid-Phase Synthesis of 2-Arylamino-5-(4-hydroxyphenyl)-1,3,4-thiadiazole Derivatives Based on Resin-Bound Acylhydrazines

A highly efficient, solid-phase synthesis of 2-arylamino-5-(4-hydroxy-phenyl)-1,3,4-thiadiazole derivatives under mild conditions has been developed. The 1,3,4-thiadiazole derivatives were synthesized from resin-bound acylhydrazines in several steps, which gave 78–88% overall yields and excellent purities of the products.     

Reactions of trifluoro- and hexafluoroacetylacetones with thiobenzoylhydrazine

The reaction of thiobenzoylhydrazine with trifluoroacetylacetone leads to the product of condensation at the CH₃C=O bond with the 5-hydroxy-2-pyrazoline structure. The tautomeric transition to the 2,3-dihydro-1,3,4-thiadiazole isomer occurs in solution. This isomer undergoes the cleavage to 2-methyl-5-phenyl-1,3,4-thiadiazole and trifluoroacetone. The reaction of thiobenzoylhydrazine with hexafluoroacetylacetone affords one of diastereomers of [3,5-dihydroxy-3,5-bis(trifluoromethyl)pyrazolidin-1-yl](phenyl)thioketone, which at equilibrium is transformed in solution into the second diastereomer of the 3,5-dihydroxypyrazolidine form followed by the elimination of water elements and formation of a tautomeric 5-hydroxy-2-pyrazoline-2,3-dihydro-1,3,4-thiadiazole mixture.     

Kinetic investigation of the alkylation of salts of 2,5-dimercapto-1,3,4-thiadiazole

A kinetic investigation has been carried out, using electronic absorption spectra, of the alkylation with benzyl chloride of the dihydrazine, monohydrazine, and the disodium salts of 2,5-dimercapto-1,3,4-thiadiazole, and also of the hydrazine and sodium salts of 5-benzylthio-2-mercapto-1,3,4-thiadiazole. The rates orders and constants were established for the benzylation reaction and it was noted that the reaction rate depends on the cation of these salts and the degree of substitution of the 2,5-dimercapto-1,3,4-thiadiazole.Institute of Chemistry, Vilnius LT-2600, Lithuania; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 972–977, July, 2000.     

X-ray Diffraction Analysis of Zn(II) Acetate Complex with 2-Amino-5-ethyl-1,3,4-thiadiazole

Results of a single-crystal X-ray diffraction study of the complex of zinc(II) acetate with 2-amino-5-ethyl-1,3,4-thiadiazole were presented. The coordination polyhedron of the complex has a distorted tetrahedral configuration with nitrogen atoms of the two 2-amino-5-ethyl-1,3,4-thiadiazole molecules and oxygen atoms of the two acetate ions coordinated to the central ion.     

Transformation of 1,3,4-Oxadiazoles to 1,3,4-Thiadiazoles Using Thiourea

A new and convenient procedure for the direct conversion of 1,3,4-oxadiazoles to 1,3,4-thiadiazole using thiourea as thionating agent is described.     

Synthon-Based Approach to the Design of Macroheterocyclic Compounds Using Diaminothiadiazoles and Diamonotriazoles

Russian Journal of General Chemistry - Synthesis and properties of 2,5-diamino-1,3,4-thiadiazole, 3,5-diamino-1,2,4-thiadiazole, 3,5-diamino-1H-1,2,4-triazole,...     

Mesoionic compounds—XIX: Mass spectral fragmentation patterns for some five-membered systems containing oxygen,nitrogen and sulfur

Mesoionic compounds of the s-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,3-thiadiazole, 1,3-thiazole and 1,3-dithiole systems all underwent deep-seated decomposition on electron-impact to small stable ions, determined to a large extent by the nature of the peripheral heteroatoms and the exocyclic substituent. In some instances fragmentation most probably involved an open-chain isomer of the cyclic system.     

Solid phase synthesis of an extensively focused library of thiadiazole ethers

An approach to combine the advantages of random and of focused combinatorial libraries in pharmaceutical research is described with the example of a solid phase synthesis of 2,5-disubstituted thiadiazole ethers. Key steps of synthesis are the introduction of the heterocycle by selective, sequential nucleophilic double substitution of 2,5-bis(methylsulfonyl)-1,3,4-thiadiazole and the oxidation of the benzylsulfanyl-1,3,4-thiadiazole to the corresponding sulfone using MCPBA on solid phase.     

N-[5-(Е)-1,3,4-噻二唑-2-基]-N'-芳基脲的合成、晶体结构及生物活性

为了寻找高活性的脲类细胞分裂素,通过2-氨基-5-(Е)-苯乙烯基-1,3,4-噻二唑与芳酰基叠氮化物反应,合成了11种新的含1,3,4-噻二唑环芳基脲类衍生物,其中芳酰基叠氮化物直接由芳酸、三氯氧磷与叠氮钠采用"一锅法"制得,再经加热发生Curtius重排转化为异氰酸酯.目标化合物的结构用红外光谱、核磁共振氢谱、质谱和元素分析进行了表征,并用X射线单晶衍射实验测定了化合物3g的结构.初步的生物活性测试表明,部分目标化合物在10 mg/L浓度下表现出良好的细胞分裂素活性,其中3c的活性超过50%.     

Cyclic condensations of 2-amino-1,3,4-thiadiazole with 1,3-dicarbonyl compounds

The reactions of 2-amino-1,3,4-thiadiazole with 1,3-dicarbonyl compounds are described. 2,4-Pentanedione gave 2-thiocyanato-4,6-dimethylpyrimidine while diethylmalonate and ethyl acetoacetate yielded 5-hydroxy-7H-1,3,4-thiadiazolo[3,2-a]pyrimidin-7-one and 7-methyl-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-one, respectively. The structure of the latter compound was confirmed by a synthesis of the alternative isomeric structure (5-methyl-7H-1,3,4-thiadiazolo[3,2-a]pyrirnidin-7-one) from 2-amino-1,3,4-thiadiazole and α-bromocrotonic acid.