D.M. Masoud

Synthesis and biological evaluation of pyrazolo[1,5-a]pyrimidine-3-carboxamide as antimicrobial agents

Exploring novel classes of antimicrobial therapeutics is an excellent approach to face the challenge of microbial resistance. In this context, a novel series of pyrazolo[1,5-a]pyrimidines 5a–d, 10a–f, 15a, d and 16a–d were synthesized and characterized by their spectral data. The structure of 10f was confirmed by X-ray diffraction analysis of its single crystal. The antimicrobial activities of the newly synthesized compounds showed that, compounds 5a and 16d were more potent than tetracycline against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. In addition, most of the newly synthesized compounds displayed a significant antifungal activity when compared with amphotericin B. Moreover, compound 16d (27.0 ± 0.41 mm, minimum inhibitory concentration: 7.81 µg/ml) displayed excellent and the highest antifungal activity than amphotericin B (18.0 ± 0.17 mm, MIC: 15.62 µg/ml) against Fusarium oxysporum.

Synthesis of a new series of polyfunctionally substituted thiazole azo dye systems for dyeing of synthetic fibres

Purpose – This papers aim is to evaluate the dyeing performance of newly designed azo dye system based on thiazole substituted for improved dyeing when applied to synthetic fibres.Design/methodology/approach – For improved dyeing qualities, various azo dye systems were synthesised based on polyfunctionally substituted thiazole as the coupling component. The heterocyclic moiety was coupled with diazotised aromatic amines to afford the respective azo or hydrazono systems. The structure of the novel systems was elucidated based on elemental analysis and spectral data. Dyeing performance, electronic spectra and optical properties were characterised based on UV and K/S measurements. Fastness properties were evaluated.Findings – The novel systems were designed so that the functionalities located on the heterocyclic ring afforded structure modification that led not only to good dispersion but also to improved adherence on the fibre. The location of the sites led to constructing a resonating system with higher e...

Microwave synthesis, photophysical properties of novel fluorescent iminocoumarins and their application in textile printing

Purpose – This paper aims to synthesise coumarine flourescent dyes from a cheap material in a very short time with a very high yield, and by using a clean green chemistry. Design/methodology/approach – Efficient microwave synthesis for some novel iminocoumarins starts from the reaction of p-phenyl-enediamine and ethyl cyanoacetate followed by cyclocondensation with salicylaldehyde derivatives. Findings – The synthesized iminocoumarine compounds were characterized by spectroscopic methods. Absorption and fluorescence spectra of the compounds were also recorded. All compounds were fluorescent in 1,4-dioxane solution, they all emitted blue light (440-460 nm). The printing properties were studied, and their applications on printing polyester and polyamide fabrics were studied by silk screen printing. Originality/value – The authors designed efficient microwavel synthesis for some novel iminocoumarine derivatives; The novel procedure features short-reaction time, moderate yields and simple workup; All compound...

Preparation and characterisation of novel methylsulfanylpyrazolopyrimidines as heterocyclic dyes from ketene dithioacetals

Purpose – This paper aims to synthesize some new heterocyclic disperse azo dyes and their application in dyeing of polyester and polyamide fabrics.Design/methodology/approach – Pyrazolopyrimidine derivatives containing arylazo function by the reaction of 3,5‐ diaminopyrazole with ketene dithioacetals were prepared. The prepared dyestuffs are established using elemental analysis, IR measurements, 1H‐NMR and Mass spectra.Findings – 2,5‐diamino‐3‐arylazo‐N‐aryl‐6‐carboxamide‐7‐methylthio‐pyrazolo[1,5‐a]pyrimidine have been synthesized by the simple method. The dyed fabrics have a very good (4‐5) to excellent (5) results toward washing, perspiration, and rubbing fastness properties. The dyes are superior in terms of preparation and fastness properties.Research limitations/implications – The disperse azo dyes used in this paper were synthesized via a step‐wise pathway leading to the new azo dyes. In addition, the variations in substituents and sites of location on the heterocyclic moiety could also be studied....

Crystal structure of 4,6-dimethyl-2-{[3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl]sulfanyl}nicotinonitrile

In the title compound, the hydrophilic glucose residues lie in the regions z ≃ ab plane, from which the pyridyl rings project; pyridyl ring stacking parallel to the a axis links adjacent layers.

Recent trends in microwave assisted synthesis of fluorescent dyes

Purpose This paper aims to focus on the most popular technique nowadays, the use of microwave irradiation in organic synthesis; in a few years, most chemists will use microwave energy to heat chemical reactions on a laboratory scale. Also, many scientists use microwave technology in the industry. They have turned to microwave synthesis as a frontline methodology for their projects. Microwave and microwave-assisted organic synthesis (MAOS) has emerged as a new “lead” in organic synthesis. Design/methodology/approach Using microwave radiation for synthesis and design of fluorescent dyes is of great interest, as it decreases the time required for synthesis and the synthesized dyes can be applied to industrial scale. Findings The technique offers many advantages, as it is simple, clean, fast, efficient and economical for the synthesis of a large number of organic compounds. These advantages encourage many chemists to switch from the traditional heating method to microwave-assisted chemistry. Practical implications This review highlights applications of microwave chemistry in organic synthesis for fluorescent dyes. Fluorescents are a fairly new and very heavily used class of organics. These materials have many applications, as a penetrant liquid for crack detection, synthetic resins, plastics, printing inks, non-destructive testing and sports ball dyeing. Originality/value The aim value of this review is to define the scope and limitation of microwave synthesis procedures for the synthesis of novel fluorescent dyes via a simple and economic way.

A simple approach for the synthesis of coumarin fluorescent dyes under microwave irradiation and their application in textile printing

Purpose The purpose of this study is to successfully implement microwave irradiation for the rapid synthesis of novel fluorescent dyes. The prepared dyes are then applied for printing of polyester and polyamide by silk screen printing process. Design/methodology/approach A series of new N′-(methylene)-2-imino-2H-chromene-3-carbohydrazide derivatives 3a–r were synthesised in excellent yield and high atom economy by the Knoevenagel condensation of salicylaldehyde derivatives 1 and cyano-N′-methyleneaceto-hydrazide derivatives 2 in the presence of piperidine catalyst. The optical properties of the synthesised compounds were recorded; all of the compounds were found to be fluorescent in 1, 4-dioxane solution; they all emitted blue light (440-460 nm). This work shows that the optical properties strongly depend on the nature of the substituent, and indicate which type of substituent is favourable for a given application. It confirms that iminocoumarin derivatives could lead to a new generation of fluorescent probes, prone to easy modification of their chemical structure. These synthesised dyes are used to print polyester and polyamide fabrics using synthetic thickener in the printing paste for silk screen technique. Findings The structures of synthesised dyes were established and confirmed for the reaction products on the basis of their elemental analysis and spectral data (MS, IR and 1H-NMR). The suitability of the prepared dyestuffs for traditional printing on polyester and polyamide fabrics has been investigated. The prints obtained using the synthesised dyes were found to possess high colour strength and excellent overall fastness properties but relatively low light fastness. Research limitations/implications The synthesised fluorescent dyes were prepared by a simple reaction process in microwave. The optical properties for obtained dyes show include the fact that it will have various important applications. In addition, they were used for printing synthetic fabrics and were found to have good results. Practical implications The new fluorescent dyes’ system has excellent printing properties. Also they are superior in terms of yield, purity, colour strength and fastness properties which may lend them valuable commercial production. Originality/value The result of this work aimed to define the scope and limitation of the procedures for the synthesis of novel iminocoumarin dyes via a simple and economic way.

Microwave assisted one-pot synthesis of pyrazoloquinazolinone derivatives and their application on printing of synthetic fabrics

Purpose – The purpose of this paper is to synthesize some novel 2-amino-6,6-dimethyl-9-phenyl-3-(phenyldiazenyl)-6,7-dihydropyrazolo-[5,1-b]quinazolin-8(5H)-one derivatives by multi-component one-pot reaction using a microwave as a new tool for green chemistry. Design/methodology/approach – An equimolor from arylazopyrazole, 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and benzaldehyde derivatives was dissolved in Dimethylformamide (DMF) to be irradiated in a microwave for 15 minutes; after completion of the reaction, as indicated by Thin layer chromatograph (TLC), the reaction mixture was poured into ice water, filtered and then crystallized with an appropriate solvent. Findings – The structure of the synthesized dyes was established and confirmed for the reaction products on the basis of their elemental analysis and spectral data (MS, IR and 1H-NMR). These prepared dyes were used to print polyester and polyamide fabrics using synthetic thickener in the printing paste for the silk screen technique. The s...

Crystal structure of racemic 2-[(β-arabino­pyran­osyl)­sulfanyl]-4,6-diphenylpyridine-3-carbo­nitrile

In the racemic title compound, the sulfur atom is attached equatorially to the sugar ring with unequal S—C bonds. The dihedral angles between the pyridine ring and its attached phenyl groups are 42.24 (8) and 6.37 (14)°. In the crystal, a system of classical O—H⋯O and O—H⋯(O,O) hydrogen bonds links the molecules to form tube-like assemblies propagating parallel to the c-axis direction.

Synthesis of novel tetrasubstituted thiophenes based dye using sodium a-cyanoketene dithiolates as starting materials

Purpose – The study aims to synthesise new thiophene-based dyes by an efficient method using sodium a-cyanoketene dithiolates as starting components for synthesis of tetra-substituted thiophenes, which act as a coupler for the synthesised dye. The synthesised dyes are applied for printing polyamide and polyester fabrics using the screen printing technique. Design/methodology/approach – Treatment of 1 with carbon disulfide in alkaline medium forming disodium salt 2, which act as starting point for heterocyclisation to prepare these dye stuff 7. Sodium a-cyanoketene dithiolates 2 react with two moles of phenacyl bromide derivatives, forming alkylsulfanylthiophenes which react with the diazonium salt, forming the target dyestuff. These prepared dyes are used to print polyamide and polyester fabrics by using a synthetic thickener in the printing paste using screen-printing techniques. Findings – The structure of synthesised dyes were established and confirmed for the reaction products on the basis of their el...