Ranjan G. Patel

Synthesis and identification of β-aryloxyquinolines and their pyrano[3,2-c]chromene derivatives as a new class of antimicrobial and antituberculosis agents.

A new class of β-aryloxyquinolines 3a-i and their pyrano[3,2-c]chromene derivatives 6a-r incorporating a validated molecular target has been synthesized via a nucleophilic displacement and a one-pot multicomponent reaction respectively. In vitro antimicrobial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Escherichia coli, Salmonella typhi, Vibrio cholera, Aspergillus fumigatus and Candida albicans. Compounds 3c, 3e, 3g, 6f, 6l and 6q exhibited excellent antibacterial activity while compound 6p exhibited more potent antifungal activity than that of first line standard drugs. In vitro antituberculosis activity was evaluated against Mycobacterium tuberculosis H37Rv and compound 6f is emerged as the promising antimicrobial member with better antitubercular activity. Majority of the compounds appears to be better antimicrobials but poor antituberculars.

Microwave-assisted synthesis of some new tetrazolo[1,5-a]quinoline-based benzimidazoles catalyzed by p-TsOH and investigation of their antimicrobial activity

Keeping the objective to build up a new structural class of potent antimicrobials, a series of some new 4-Benzimidazol-2-yl tetrazolo[1,5-a]quinoline derivatives has been synthesized by reaction of tetrazolo[1,5-a]quinoline-4-carbaldehyde and o-phenylenediamine in the presence of an organocatalyst p-TsOH under the influence of microwave irradiation. The identity of all the compounds has been established by 1H NMR, 13C NMR, FTIR, and elemental analysis. The synthesized compounds were subjected to in vitro antimicrobial screening against a representative panel of pathogenic strains including three Gram-positive bacteria (Bacillus subtilis, Clostridium tetani, and Streptococcus pneumoniae) and three Gram-negative bacteria (Escherichia coli, Salmonella typhi, and Vibrio cholerae) as well as two fungal organisms (Aspergillus fumigatus and Candida albicans) by employing broth microdilution method. Of the compounds studied, compound 5e demonstrated significant activity against a Gram-positive bacteria Bacillus subtilis.

One-Pot, Multicomponent Condensation Reaction in Neutral Conditions: Synthesis, Characterization, and Biological Studies of Fused Thiazolo[2,3-b]quinazolinone Derivatives

A new series of 12-(2-chloro-6-quinoline-3-yl)-3,3,8-substituted-2,3,4,12-tetrahydro-benzo[4,5]thiazolo[2,3-b]quinazolin-1-ones 4 was synthesized in one pot by condensing various 2-chloro-3-formylquinolines 1, 2-amino-6-substituted-benzothiazoles 2, and 1,3-cyclohexanedione 3 in ethanol. All the compounds were characterized by IR, 1H NMR, 13C NMR spectra and elemental analysis. All the synthesized compounds were screened for their antibacterial activity against Grampositive bacterial species Bacillus cereus and Bacillus substilus, Gram-negative bacterial species Escherichia coli, and their fungicidal activity against Aspergillus niger, Fuserium oxisporum, and Rhizopus species.

EFFECTS OF REACTIVE DILUENT DIEPOXIDIZED CARDANOL AND EPOXY FORTIFIER ON CURING KINETICS OF EPOXY RESIN

Different formulations, composed of the diglycidyl ether of bisphenol-A, diepoxidized cardanol as reactive diluent, an anhydride as curing agent, and a tertiary amine as curing catalyst, with/without the use of an epoxy fortifier, were analysed. The effect of the fortifier on the diluent was also observed. The overall kinetics of curing was observed to follow a simple Arrhenius-type temperaturedependence, with an activation energy in the range 54–120 kJ/mol, with first-order kinetics up to 85% conversion. An increase in activation energy was observed with an increase of diluent content. The curing reaction was found to follow a three-step mechanism, involving a nucleophilic bimolecular displacement reaction, for which an explanation was offered. Incorporation of the fortifier lowers the curing temperature, but does not alter the final degree of reaction.ZusammenfassungEs wurden verschiedene Ausgangsgemische, bestehend aus dem Diglyzidyläther von Bisphenol A, diepoxydiertem Kardanol als reaktives Streckmittel, einem Anhydrid als Vernetzungsmittel und einem tertiären Amin als Vernetzungskatalysator mit bzw. ohne Anwendung eines Fortifyers untersucht. Der Einfluss des Fortifyers auf das Streckmittel wurde ebenfalls untersucht. Die Bruttokinetik der Vernetzung zeigt eine Temperaturabhängigkeit einfachen Arrhenius-Types mit einer Aktivierungsenergie im Bereich von 54–120 kJ/mol sowie einen Reaktionstyp erster Ordnung mit einer Konversionsrate von 85%. Ein steigender Streckmittelgehalt bewirkt ein Anwachsen der Aktivierungsenergie. Der Vernetzungsreaktion liegt ein Dreistufenmechanismus zu Grunde, der unter anderem auch eine nukleofile bimolekulare Substitutionsreaktion beinhaltet. Der Einsatz eines Fortifyers senkt zwar die Vernetzungstemperatur, verändert aber nicht die Endkonversionsrate.РезюмеИсследованы различн ые композиции, состоя щие из диглицидного эфир а бисфенолаА, диэпоксидированног о карданола, как разба вителя реакции, ангидрида, ка к вулканизирующего аг ента, и третичного ами на, как катализатора реакци и отверждения, с или без использования эп оксизакрепителя. Уст ановлено влияние закрепителя на разбавитель. Найдено, что общая кин етика реакции отверж дения подчиняется простой температурной зависимости аррениу совского типа с энерг ией активации 54–120 кдж·моль−1 и реакцией первого порядка с 85% превращени ем. Наблюдалось увели чение энергии активации с у величением содержания разбавит еля. Найдено, что реакц ия отверждения следует трехступенчатому механизму, включающе му реакцию нуклеофил ьного бимолекулярного сме рения, для которой и предложено объяснен ие. Введение закрепит еля понижает температуру отвержд ения, но не затрагивает конечну ю степень реакции.

Microwave assisted synthesis and antimicrobial evaluation of new fused pyran derivatives bearing 2-morpholinoquinoline nucleus.

A new series of fused pyran derivatives 5a-x bearing 2-morpholinoquinoline nucleus has been synthesized under microwave irradiation by a reaction of 2-morpholinoquinoline-3-carbaldehyde 2a-c, malononitrile 3 and compounds 4a-h in presence of NaOH as basic catalyst. All the compounds were screened against three Gram positive bacteria (Streptococcus pneumoniae, Clostridium tetani, Bacillus subtilis), three Gram negative bacteria (Salmonella typhi, Vibrio cholerae, Escherichia coli) and two fungi (Aspergillus fumigatus, Candida albicans) using broth microdilution MIC (Minimum Inhibitory Concentration) method. Of the compounds studied, compounds 5b, 5f, 5k, 5m, 5q, 5s and 5v have found to be most efficient members of the series.

Synthesis and antimicrobial screening of pyrano[3,2-c]chromene derivatives of 1H-pyrazoles

AbstractA new series of twenty four derivatives of pyrano[3,2-c]chromene IVa-x bearing 1H-pyrazole were synthesized by a one pot, base-catalyzed cyclocondensation reaction of 1H-pyrazole-4-carbaldehyde Ia-l, malononitrile II and 4-hydroxycoumarin IIIa-b. All the synthesized compounds were characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectral data. All the synthesized compounds were screened against six bacterial pathogens, namely B. subtilis, C. tetani, S. pneumoniae, S. typhi, V. cholerae, E. coli and for antifungal activity against two fungal pathogens, A. fumigatus and C. albicans using the broth microdilution MIC method. Some of the compounds were found to be equipotent or more potent than commercial drugs against most of employed strains, as evident from the screening data.

Synthesis and Antimicrobial Evaluation of New Pyrano[4,3‐b]pyran and Pyrano[3,2‐c]chromene Derivatives Bearing a 2‐Thiophenoxyquinoline Nucleus

A new series of pyrano[4,3‐b]pyran 4a–i and pyrano[3,2‐c]chromene 6a–r derivatives bearing a 2‐thiophenoxyquinoline nucleus were synthesized by reaction of 2‐(4‐(un)‐substituted thiophenoxy)quinoline‐3‐carbaldehydes 2a–i with 6‐methyl‐4‐hydroxypyran‐2‐one 3 and 4‐hydroxy‐6‐(un)‐substituted‐2H‐chromen‐2‐one 5a–b respectively and malononitrile at room temperature in the presence of KOH as a basic catalyst. All the compounds were screened against three Gram‐positive bacteria (Streptococcus pneumoniae, Bacillus subtilis, Clostridium tetani), three Gram‐negative bacteria (Salmonella typhi, Escherichia coli, Vibrio cholerae) and two fungi (Candida albicans, Aspergillus fumigatus) using the broth microdilution MIC (minimum inhibitory concentration) method. Upon antimicrobial screening, it was observed that the majority of the compounds were found to be active against Bacillus subtilis, Clostridium tetani and Candida albicans as compared to standard drugs.

A New Cationic Poly[1-vinyl-3-ethyl imidazolium iodide], P(VEII) Hydrogel for the Effective Removal of Chromium (VI) from Aqueous Solution

Cationic porous and non-porous hydrogels have been prepared via free radical solution polymerization using newly synthesized 1-vinyl-3-ethyl imidazolium iodide (VEII) monomer and N,N′-methylenebisacrylamide as crosslinker. The hydrogel has been characterized by FT-IR, mercury porosimetery and TGA analysis. Their surface morphology was observed using scanning electron microscope (SEM). The swelling kinetics of porous and non-porous P(VEII) hydrogels in solutions of chromium(VI) was determined using a gravimetric method. A batch system was applied to study the adsorption of chromium(VI) from aqueous solutions by cationic hydrogels. The effect of treatment time, pH of the medium, amount of adsorbent dose and initial feed concentration of metal ion on adsorption of chromium(VI) from their solution were also investigated. Adsorption of chromium(VI) increases with the increase in treatment time, adsorbent dose and initial feed concentration and decreases with the increase in pH of the medium. Desorption of chromium(VI) was carried out using various eluents and almost 100% desorption was observed, so the P[VEII] hydrogel can be used repeatedly for the adsorption of chromium(VI).

Fused heterocycle 11-amino-13H-acenaphtho[1,2-e] pyridazino[3,2-b]quinazoline-13-one based monoazo disperse dyes

Abstract A series of new heterocyclic monoazo disperse dyes have been prepared by coupling 11-amino-13H-acenaphtho[1,2-e]pyridazino[3,2-b]quinazoline-13-one with various mono and di-N substituted derivatives of aniline. All the disperse dyes were characterized by their percentage yield, melting point, UV–visible spectroscopy, elemental analysis, infrared spectroscopy and dyeing performance on Nylon 66 and polyester fibres. The percentage dye bath exhaustion on different fibres have been found to be reasonably good and acceptable. The dyed fibres show fairly good to good fastness to light and very good to excellent fastness to washing, rubbing, perspiration and sublimation.

Investigation of kinetics of curing of triglycidyl-p-aminophenol with aromatic diamines by differential scanning calorimetry

The kinetics of curing of triglycidyl-p-aminophenol with four different diamines in stoichiometric amounts were investigated by means of differential scanning calorimetry. The results indicated that the curing reaction follows first-order Arrhenius kinetics with an activation energy in the range 40–70 kJ · mol−1. The effect of the structure of the curing agent on the curing characteristics is discussed on the basis of the curing characteristics and the kinetic parameters. An epoxy fortifier was observed to lower the curing temperature of an epoxy-amine system when incorporated prior to curing.ZusammenfassungMittels Differential-Scanning-Kalorimetrie wurde die Kinetik der Vernetzung von Triglycidyl-p-aminophenol mit stöchiometrischen Mengen vier verschiedener Amine untersucht. Laut den Ergebnissen verläuft die Vernetzungsreaktion mit einer Arrhenius-Kinetik erster Ordnung, wobei die Aktivierungsenergie im Bereich von 40–70 kJ/mol liegt. Auf Grundlage der Vernetzungscharakteristika und der kinetischen Parameter wird der Einfluss der Struktur des Vernetzungsreagenz auf die Vernetzungskenndaten beschrieben. Mit einem vor der Vernetzung eingebrachten Epoxyfortifyers konnte die Vernetzungstemperatur eines Epoxy-Amin-Systemes heruntergesetzt werden.РЕжУМЕМЕтОДОМ Дск ИсслЕДОВ АНА кИНЕтИкА ОтВЕРжД ЕНИь тРИглИцИДИл-п-АМИНОФ ЕНОлА с ЧЕтыРьМь РАжлИЧНыМИ ДИАМИНАМИ, Вжьтых В стЕхИОМЕтРИЧЕскИх к ОлИЧЕстВАх. РЕжУльтА ты пОкАжАлИ, ЧтО РЕАкцИь ОтВЕРжДЕНИь пОДЧИНь Етсь АРРЕНИУсОВскОИ кИНЕ тИкЕ пЕРВОгО пОРьДкА с ЁНЕРгИЕИ АктИВАцИИ В ИНтЕРВАлЕ 40–70 кДж·МОль−1. НА ОсНОВЕ кИНЕтИЧЕскИх пАРАМЕтРОВ ОБсУжДЕНО ВлИьНИЕ ст РУктУРы ВУлкАНИжИРУ УЩЕгО АгЕНтА НА хАРАктЕРИстИкИ РЕ АкцИИ ОтВЕРжДЕНИь. УстАНОВлЕНО, ЧтО ЁпОк сИжАкРЕпИтЕль, ВВЕДЕ ННыИ РАНьшЕ ВУлкАНИжИРУУЩЕгО Аг ЕНтА, пОНИжАЕт тЕМпЕРАтУР У ОтВЕРжДЕНИь.