Synthesis and Application of Disperse Dyes Based on 2-Aminothiazole Derivatives

A series of novel monoazo disperse dyes based on 2-amino-5-nitro-4-(p-nitrophenyl)thiazole were prepared using various N,N-dialkylaniline derivatives as the coupling components. The spectral properties in the IR and visible range of the dyes were investigated. The dyeing performance of these dyes was assessed on nylon fabric. These dyes were found to give a wide range of color shades from reddish brown to indigo with excellent brightness, levelness, and depth on nylon fabric. The dyed fabric showed fairly good light fastness, good to excellent fastness to wash and perspiration, and excellent fastness to sublimation. The dyebath exhaustion and fixation of the dyes on nylon were found to be very good and acceptable.     

Synthesis and Application of Some Alkali‐Clearable Azo Disperse Dyes Based on Naphthalimide Derivatives

A series of naphthalimide‐based alkali‐clearable azo disperse dyes containing a fluorosulfonyl group was synthesized. 4‐Fluorosulfonylaniline, 4‐fluorosulfonyl‐2‐nitroaniline and 6‐chloro‐4‐fluorosulfonyl‐2‐nitroaniline as the diazo components were prepared from N‐acetylsulfanilyl chloride and were subsequently coupled with 4‐hydroxy‐N‐3‐methoxypropyl‐1, 8‐naphthalimide. The synthesized dyes and their intermediates were characterized by the use of DSC, FTIR, ¹H NMR, ¹³C NMR, Mass spectroscopy and UV‐visible spectroscopic techniques. Spectrophotometric investigations of prepared dyes in different solvents were carried out in order to obtain their absorption maxima, molar extinction coefficients and solvatochromic effects. The obtained dyes were applied to polyester fabric by the HT method and exhibited good leveling, wash and sublimation fastnesses and moderate light fastness. The synthesized dyes showed that incorporated fluorosulfonyl group to these dyes can be converted to the dyes containing a water soluble sulfonate group in the relatively mild alkaline conditions.     

Studies on Synthesis of Novel Triazole Tagged Pyrazole Fused Naphthalene 5‐Thiazine‐5,5‐dioxide Derivatives,Their Antimicrobial,and Antioxidant Activity

A series of novel triazole tagged pyrazole fused naphthalene‐5‐thiazine‐5,5‐dioxide derivatives 8 and 9 were synthesized starting from sodium salt of saccharin 1 . The structure of each intermediate and products was established on the basis of spectroscopy data. All the synthesized compounds 8 and 9 were screened against various bacterial and fungal strains but found to show no activity up to 150‐µg/mL concentration. Further screening for antioxidant property resulted promising compounds.     

Synthesis and Antimicrobial Activities of Novel Series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one Derivatives

In the present investigation, a novel series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one derivatives were synthesized by condensation of 2‐substituted‐4‐methylthiazole‐5‐carbaldehyde with 4‐(2‐substituted thiazol‐4‐yl)benzenamine followed by cyclo‐condensation with thioglycolic acid in toluene. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, and Mass) methods. The title compounds were screened for quantitative antibacterial activity (minimal inhibitory concentration). All compounds 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h and 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h show moderate to good antimicrobial activity, whereas compounds ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h ) also show moderate antifungal activity.     

Heterocycles Derived from 5‐(2‐Aminothiazol‐4‐yl)‐8‐hydroxyquinoline: Synthesis and Antimicrobial Activity

5‐(2‐Aminothiazol‐4‐yl)‐8‐hydroxyquinoline 2 has been synthesized by treating thiourea with 5‐chloroacetyl‐8‐hydroxyquinoline 1 . The amine 2 was treated with aromatic aldehydes to furnish schiff bases 6a‐c which on treatment with phenyl isothiocyanate gave the corresponding thiazolo‐s‐triazines 7a‐c . Reaction of 2 with phenyl isothiocyanate gave the corresponding aminocarbothiamide derivative 8 which on reaction with malonic acid in acetyl chloride afforded thiobarbituric acid derivative 9 . Coupling of 9 with diazonium salt gave the phenyl hydrazono derivative 10 . However, reaction of 2 with carbon disulphide and methyl iodide afforded dithiocarbamidate 12 which on treatment with ethylenediamine, o‐aminophenol and/or phenylenediamine gave the aminoazolo derivatives 13–15 , respectively. Other substituted fused thiazolopyrimidines 16–20 have been also prepared by the reaction of 2 with some selected dicarbonyl reagents. The characterisation of synthesized compounds has been done on the basis of elemental analysis, IR, ¹H‐NMR and mass spectral data. All the newly synthesized compounds have been screened for their antimicrobial activities.     

Synthesis and Antimicrobial Activity of Novel 2‐Substituted Phenoxy‐N‐(4‐substituted Phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐yl)acetamide Derivatives

A series of 2‐substituted phenoxy‐N‐(4‐substituted phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazole‐2‐yl)acetamide derivatives 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j , 8k , 8l , 8m , 8n , 8o , 8p , 8q , 8r , 8s , 8t was synthesized by the reaction of phenoxyacetyl chloride 7 with intermediate 4‐substituted phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐amine 5 . Their structures were confirmed by ¹H NMR, ¹³C NMR, MS, IR, and elemental analyses. The synthesized compounds were also screened for their antimicrobial activity against three types of plant fungi (Gibberella zeae , Phytophthora infestans , and Paralepetopsis sasakii ) and two kinds of bacteria [Xanthomonas oryzae pv. oryzae (Xoo ) and Xanthomonas axonopodis pv. citri (Xac )] showing promising results. In particular, 8b , 8f , 8g , and 8h exhibited excellent antibacterial activity against Xoo , with 50% effective concentration (EC₅₀) values of 35.2, 80.1, 62.5, and 82.1 µg/mL, respectively, which are superior to the commercial antibacterial agent bismerthiazol (89.9 µg/mL). The preliminary structure–activity relationship studies of these compounds are also briefly described.     

Synthesis and Antimicrobial Activity of New Substituted 5‐(Pyridine‐3‐yl)‐1,3,4‐Thiadiazoles and Their Sugar Derivatives

New substituted 5‐(pyridine‐3‐yl)‐1,3,4‐thiadiazoles, their sugar hydrazones and acyclic C‐nucleoside analogs as well as the corresponding thioglycoside derivatives were synthesized. The synthesized compounds were tested for their antimicrobial activity against Escherichia coli, Bacillus subtilis, Staph aureus, Aspergillus niger, and Candida albicans The obtained results indicated that most of tested compounds exhibited moderate to high antimicrobial activity while few compounds were found to exhibit little or no activity against the tested microorganisms.     

Synthesis and Antimicrobial Activity of N‐[(2Z)‐3‐(4,6‐Substitutedpyrimidin‐2‐yl)‐4‐phenyl‐1,3‐thiazol‐2(3H)‐ylidene]‐3, 5‐dinitrobenzamide Analogues

In this study, we have synthesized 1‐(4,6‐disubstitutedpyrimidin‐2‐yl)‐3‐(3,5‐dinitrobenzoyl)‐thiourea derivatives ( 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h ) and N‐[(2Z)‐3‐(4,6‐disubstitutedpyrimidin‐2‐yl)‐4‐phenyl‐1,3‐thiazol‐2(3H)‐ylidene]‐3, 5‐dinitrobenzamide ( 2a‐2h ) analogues and characterized by IR spectroscopy, NMR spectroscopy, elemental analysis, and single crystal X‐ray diffraction data. The compounds ( 2a‐2h ) were screened for antimicrobial activity against Gram positive, Gram negative, and fungal species. The results of antimicrobial study indicated that compounds showed most potential and appreciable antibacterial and antifungal activities.     

Synthesis of 1‐(p‐Sulphophenyl)‐3‐methyl‐5‐pyrazolone Based Acid Dyes and Their Applications on Leather

A new series of pyrazolone based azo acid dyes (3a–g) has been synthesized starting from 1‐(p‐sul‐phophenyl)‐3‐methyl‐5‐pyrazolone (1). The synthetic methodology included the nitrosation of p‐sulphophenyl methyl pyrazolone followed by reduction, diazotization and coupling with Naphthol AS derivatives (2a–f), in alkaline medium to yield different acid dyes. Multichromic metal complexes of these dyes (5a–f, 6a–f and 7a–f) with 3d transition metals Chromium, Iron and Copper were also synthesized. The structures of all of newly synthesized compounds were confirmed by analytical data and spectroscopic techniques. The synthesized dyes were applied on leather to assess their light fastness, wash fastness and rubbing fastness and were shown to exhibit high values of 4–5 for majority of dyes.     

Synthesis of Novel 2‐Amino‐(2‐thioxo‐3‐alkyl‐4‐methyl‐3H‐thiazol‐5‐yl)‐[1,3,4]thiadiazole Derivatives and Their Growth Stimulant Activity

On the base of synthesized 2‐amino and 2‐ethylamino‐(2‐thioxo‐3‐alkyl‐4‐methyl‐3H‐thiazol‐5‐yl)‐[1,3,4]thiadiazoles, their alkyl, acetyl, and alkylacetylamino derivatives are obtained. The alkylation of 2‐ethylamino derivatives can occur at both exo and endo nitrogen atoms of amidine group, and the acetylation takes place exclusively at the exocyclic nitrogen atom. At acetylation of 2‐amino‐[1,3,4]thiadiazoles, only exo substitution is observed. At the further alkylation of these products, a mixture of exo‐ and endo‐substituted forms is obtained. At preliminary screening, the synthesized compounds have shown expressed growth stimulant properties. The activity of the most active derivatives was in the range of 65–100%, compared with that of heteroauxin.     

Synthesis of Some New Thiazolo[3,2‐a]pyrimidine Derivatives and Their Applications as Disperse Dyes

A series of novel thiazolo[3,2‐a]pyrimidine derivatives were synthesized by using β‐ketoanilides 1a–c as starting materials and as key intermediates for preparation of new pyrimidinecompounds 3a–e and fused heterocyclic pyrimidine derivatives 5a–c . The new compounds were transformed to disperse dyes 6a,b and 7 . The chemical structures were elucidated by spectroscopic and elemental analyses and found to be in good agreement with the proposed structures. The versatility of compounds 6a,b and 7 for textile dyeing as disperse dyes was reported. The synthesized dyes were applied to polyester fabrics by using high temperature dyeing method at 120°C. The dye uptake expressed as color strength (k/s) of the dyed samples has been measured. Moreover, the color strength was examined in detail. In addition, the position of color in CIELAB coordinates (L*, a*, b*, h, and C*) was assessed. The color fastness of the dyed samples gave excellent results for washing and rubbing; however, the light fastness was moderate. Raman spectra of dyed samples unequivocally excluded ring dyeing and found to match with the proposed structures.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

New 1,3,4‐Thiadiazole Derivatives: Synthesis,Characterization, and Antimicrobial Activity

In the present study, 2,5‐bis(mercapto‐acetichydrazide)‐1,3,4‐thiadiazole ( 1 ) was utilized by different reagents, namely, ethoxymethylene malononitrile, ethoxymethylene ethyl cyanoacetate, triethyl orthoformate, phenyl isothiocyanate, carbon disulfide, isatin, acetophenone, cyclohexanone, different aldehydes, and different anhydrides, to yield a new series of 2,5‐disubstituted‐1,3,4‐thiadiazoles 2 – 18 . The chemical structure of these products was characterized by the spectral data IR, ¹H‐NMR, ¹³C‐NMR, MS, and elemental analysis. All the synthesized compounds were screened for their antibacterial activity.     

Synthesis and Antimicrobial Activity of Polyfunctionally Substituted Heterocyclic Compounds Derived from 5‐Cinnamoylamino‐2‐Cyanomethyl‐1,3,4‐Thiadiazole

Cinnamoyl isothiocyanate 1 was reacted with 2‐cyanoethanoic acid hydrazide 2 to afford 1‐cyanoacetyl‐4‐substituted thiosemicarbazide 3, which on treatment with a mixture of glacial acetic acid and acetic anhydride gave the desired 5‐cinnamoylamino‐2‐cyanomethyl‐1,3,4‐thiadiazole 4 . Compound 4 was subjected to react with aromatic aldehydes, phenylisothiocyanate, carbon disulphide, and arylidene malononitrile to give coumarin 5 , thiazolidines 8 , 9, and 1,3,4‐thiadiazolo[3,2‐a]pyridine 13 derivatives. The structures of all synthesized compounds were ascertained by spectral and analytical data. Antimicrobial activity of some of prepared compounds was investigated, and compounds 7, 8 were found to exhibit the highest strength.     

Microwave and Ultrasound‐Assisted Synthesis of Thiosemicarbazones and Their Corresponding (4,5‐Substituted‐thiazol‐2‐yl)hydrazines

Hantzsch cyclization of thiosemicarbazone intermediates is a very popular approach to the synthesis of substituted thiazoles. We developed a convenient microwave and ultrasound‐assisted method both for the synthesis of 1‐(alkyliden/cycloalkyliden/aryliden)thiosemicarbazone intermediates and their cyclization into (4,5‐substituted‐thiazol‐2‐yl)hydrazines. The search for optimal reaction conditions included the use of different catalysts (Lewis acids and resins) and solvents at discrete temperatures, pressures, and irradiation powers. Comparing yields, reaction times, and efforts proved that microwave and ultrasound‐assisted techniques outmatch conventional heating and have a remarkable influence on the synthesis.     

Synthesis of Some Novel Arylazo Disperse Dyes Derived from 5‐Amino‐tetrazolo[1,5‐a]pyrimidin‐7‐ol as Coupling Component and Investigation of Their Absorption Spectra

5‐amino‐tetrazolo[1,5‐a]pyrimidin‐7‐ol ( I ) was synthesized by reaction of 5‐amino‐tetrazole with ethyl cyanoacetate in excellent yield. A series of novel 5‐amino‐6‐arylazotetrazolo[1,5‐a]pyrimidin‐7‐ol dyes were prepared by linking o‐, m‐, p‐anisidine, o‐, m‐, p‐chloroaniline, o‐, m‐, p‐nitroaniline, o‐, m‐, p‐toluidine and aniline to 5‐amino‐tetrazolo[1,5‐a]pyrimidin‐7‐ol ( I ). The structure of these dyes were confirmed by UV‐vis, FTIR and ¹H NMR spectroscopic techniques and elemental analysis. The effect of varying pH and solvent upon the absorption ability of 5‐amino‐6‐arylazotetrazolo[1,5‐a]pyrimidin‐7‐ol sudstituted with electron‐withdrawing and electron‐donating groups at their o‐, m‐, p‐position was examined.     

Synthesis and Antimicrobial Activity of New 2,5‐Disubstituted 1,3,4‐Oxadiazoles and 1,2,4‐Triazoles and Their Sugar Derivatives

A series of new 2,5‐disubstituted‐1,3,4‐oxadiazole and 1,2,4‐triazole derivatives were synthesized by heterocyclization of acid hydrazide 1 and thiosemicarbazide derivative 2 . Furthermore, the acyclic C‐nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.