جستجوی مقالات مرتبط با کلیدواژه « methyl » در نشریات گروه « شیمی »

3-((6-methyl-5-oxo-3-thioxo-2,5-dihydro-1,2,4-triazin-4(3H)-yl)imino)indolin-2one was used as a neutral ion carrier in the PVC membrane to construction of a new zinc ion selective electrode. The sensor shows a good Nernstian response for Zn2 over a wide concentration range of 1.0×10-5 to 1.0×10-1 mol L-1 with a slope of 27.12 mV per decade. The limit of detection of the sensor is 8×10-6 mol L-1. The sensor has a relatively fast response time (~5 s) and a useful working pH range of 4.4-8.0 and it can be used without any divergence in Nernstian response for 60 days with high reproducibility. Interference of some cations was also evaluated and it exhibits an appropriate selectivity. Finally it was used as an indicator electrode in potentiometric titration of Zn2 with EDTA and in direct determination of Zn2 in rice and in zinc enriched soufflé cake samples. The results indicate that this electrode is sensitive for determination of Zn2 ion.

An efficient and eco-friendly method is introduced for the synthesis of 4,4'-(arylmethylene)-bis-(1H-pyrazol-5-ols) by the condensation reaction of two equivalents of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one with various aromatic aldehydes, catalyzed by the boehmite nanoparticles (BNPs). This heterogeneous catalyst was recycled and used in four runs for the reaction between benzaldehyde and 3-methyl-l-phenyl-5-pyrazolone without any loss of its catalytic activity.

Two new spectrophotometric methods (M1 and M2) are developed for the determination of vardenafil in bulk and in tablet dosage forms. The method M1 involves oxidative coupling of vardenafil with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in presence of ferric chloride in acidic medium yielding green colored chromogen with absorption maxima at 625 nm. The method M2 is based on the oxidation of 4-aminoantipyrine by potassium periodate, which subsequently couples with vardenafil in an alkaline medium to form a red colored product having absorption maxima at 530 nm. The absorbance concentration graphs were rectilinear over the range of 4-40 μg ml-1 for the method M1 and 4-60 μg ml-1 for the method M2. The limit of detection values was found to be 0.044 μg ml-1 and 0.035 μg ml-1 for the methods M1 and M2, respectively. The analytical performance of the developed methods was fully validated as per the guidelines prescribed by International Conference on Harmonization. The results were found to be acceptable. The application of the proposed methods in the determination of vardenafil in their commercial tablet dosage forms was successful showing good percentage recoveries.

Nanomagnetite-Fe3O4 is used as a highly efficient, mild, green and recyclable nanomagnetite catalyst for the synthesis of 4,4´-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives in solvent-free conditions. The condensation reaction of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one with aromatic aldehydes affords the title compounds in high yields and short reaction times. The nanocatalyst is reusable for seven times without significant loss of its catalytic activity. Short reaction times, high yields, generality, efficiency, recyclability of the catalyst for seven times, simple purification, clean reaction, and agreement with the green chemistry protocols are some advantages of in this method. the catalyst was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM).

Friedel–Crafts synthesis of triarylmethanes over 3-methyl-1-sulfonicacid imidazolium tetrachloroaluminate under green conditions:In this work, Friedel–Crafts (FC) alkylation of various arenes with aromatic aldehydes catalyzed by 3-methyl-1-sulfonic acid imidazoliumtetrachloroaluminate {[Msim]AlCl4}, as a green catalyst, to prepare triarylmethanes (TAMs) has been carried out. Some aromatic aldehydes were reacted with arenes containing electron-donor substitutions such as anisole, veratrole, phenols, indole and 2-naphtole under solvent-free conditions. The catalyst was recovered and reused successfully for four times. Simple methodology, easy work up, solvent-free condition and excellent yields are some advantages of this work.The promising points for the presented method are high yield, green reaction profile, easier work up and simplicity which make it a useful process for the preparation of various triarylmethanes

3-methyl-1-(4-sulfobuthyl)-1-H-imidazol-3ium hydrogen sulfate, as a dual acidic ionic liquid (DAIL), was found to be an efficient catalyst for the simple, rapid and green synthesis of substituted trisphenols from the condensation of different substituted phenols and 2,6-bis (methylol) phenols (BMP). DAIL catalyst efficiently promoted the reaction between phenols and BMPs with a variety of functionalities. Use of a non-corrosive and reusable catalyst, high yields of the products, short reaction times and solvent-free conditions are as worthwhile advantages of the present method.

Cellulose sulfuric acid was used as an efficient biopolymer-based catalyst for the synthesis of tetrahydropyrimido[4,5-b]quinoline-2,4,6-triones and hexahydro-2H-pyrazolo[5,4-b]quinoline-6-ones via three component reaction of aldehyde, 5,5-dimethyl-1,3-cyclohexadione and 6-amino-1,3-dimethyluracil or 5-amino-3-methyl-1-phenypyrazole under solvent-free conditions at 90 oC. The major advantages of the present method are simple experimentation, use of inexpensive and eco-friendly reusable catalyst with good yields and short reaction times.

In this study, a Hg2+ potentiometric membrane sensor was prepared based on the highly selective complexation between 4-(benzylidene amino)-3,4-dihydro-6-methyl-3- thioxo-1,2,4-triazin-5(2H)one as ionophore and Hg2+ ion. The electrode exhibits a Nernstian response for Hg2+ over a concentration range (1.0×10-2 to 1.0×10-6 M) with a slope of29.06±0.4 mV per decade. The limit of detection of the sensor is 6.0×10-7 M. The sensor has a relatively fast response time (~10 s) and a useful working pH range of 3.5–6.5. Interference of some cations was also evaluated. It was used as an indicator electrode in potentiometric titration of Hg2+ ion with EDTA and in direct determination of Hg2+ in water and wastewater samples. The results indicate that this electrode is sensitive for determination of Hg2+ ion.