An-Najah Blogs :: organic chemistry An-Najah Blogs :: organic chemistry en-us Sun, 03 Jul 2022 15:18:58 IDT Sun, 03 Jul 2022 15:18:58 IDT Synthesis and antimicrobial activity of new N-methyl-N-(2-pyridyl) aromatic and heteroaromatic hydrazones ArticlesAromatic and heteroaromatic N-methyl-N-2-pyridyl-hydrazones 3a-f were synthesized and characterized by elemental analyses and spectral data H-1 C-13 NMR and mass spectra supported the formation of the E-isomer N-Methyl-N-2-pyridylhydrazone carboxaldehydes can be readily characterized by mass spectrometry The new hydrazones 3a-h have been screened for antimicrobial activitySolvent Effect on Nucleophilic Cleavage of p-Chlorobenzyltrimethylsilane Using Tetrabutylammonium Fluoride in ROH-DMSO Media ArticlesThe rates of cleavage of p-chlorotrimethylsilane were measured in various ROH-DMSO meda R: Me Et i-Pr t-By CFCH-HOCHCH- and the results were reported These results have shown that the rates of cleavage decrease as the mole ratio of ROH increasesNucleophilic Cleavage of Substituted Benzyltrimethylsilanes using Tetraalkylammonium Fluoride in DMSO-H20 Media ArticlesThe nucleophilic cleavage of substituted benzyltrimethyl-silanes in DMSO-Hz0 media using tetraalkylammonium fluoride TAAF has been studied The observed rate constants pseudo first order rate constants activation and thermodynamic parameters have been reported A mechanism for such cleavage has been proposed The results fit well Hammett equation The reaction constant p value of 67 has been reported The p value is consistent with a substantial negative charge developing in the transition state Simultaneous Spectrophotometric Determination of Iron(II) and Iron(III) in Mixtures Using Di-2-pyridyl Ketone Benzoylhydrazone ArticlesA method for simultaneous spectrophotometric determination of total iron ironII and ironIII in mixtures containing other metal ions has been described The method is based on the complexation of iron with di-2-pyridyl ketone benzoylhydrazone DPKBH in 50 vv ethanolic solution IronII complex with DPKBH exhibits two absorption maxima at 360 and 650 nm meanwhile ironII1 complex with DPKBH exhibits only one maximum at 360nm IronII and ironIII complexes with DPKBH have similar behaviour at 360nm Iron forms 1:2 complexes with the reagent Beers laws are obeyed over the ranges 01-2 gml-1 and 04-5 grn1-l for ironII complexes at 360 and 650nm respectively IronIII showed results similar to those obtained for ironII at 360nm The effect of pH effect of excess reagent the stability of complexes and the tolerance limit of many metal ions have been reported The method is applied to the determination of total iron ironI1 and ironII1 in synthetic solutions Spectroscopy Letters Volume 22 Issue 9 November 1989 pages 1203 - 1214Kinetic studies of the hydrolysis of furfurylidene benzoylhydrazone ArticlesThe hydrolysis of furfurylidene benzoylhydrazoneFBH in hydrochloric acid medium has been found to follow specific acid catalysis whereas the hydrolysis in universal buffer medium has been found to follow general acid-base catalysis Mechanisms for the hydrolysis in different acidic media have been postulated The observed rate constants secondary rate constants activation and thermodynamic parameters for the hydrolysis of furfurylidene benzoylhydrazone have been reported The effect of change in percentage of ethanol in the ethanol-buffer mixture on the rate of hydrolysis has been discussed Monatshefte fr Chemie Chemical Monthly Volume 120 Number 4 April 1989 Kinetics and Mechanism of the Hydrolysis of Benzylidene Benzoylhyd - Razone Derivatives ArticlesThe kinetics and mechanism of hydrolysis of a series of substituted benzylidene benzoylhydrazones X BBH have been studied at five different temperatures in the range 25 45c by U V -visible spectrophotometry The hydrolysis reactions were found to follow first - order kinetics A mechanism has been postulated in which the attack of water on the protonated substrate is subject to general base catalysis This mechanism has been supported by the effect of anion concentration of buffer at constant pH on the observed rate constant The Bronsted -value for the hydrolysis reaction is 073 Hammett correlations Arrhenius and thermodynamic parameters have been evaluated and discussed The pKa values for the conjugate acids for benzylidene benzoylhydrazones derivatives X - BBH have been determinedBase Cleavage of Some Benzyl-Silicon and Tin Compounds in H2O-MeOH-Cyclodextrin Medium ArticlesThe effects of oc - and f3- cyclodextrin x - 13- CDs on the rates of base cleavage of 4 - CNC6 H4 SnMe3 3CIC6 H4 CH2 MMe3 4 C1C6 H4 CH2 MMe3 and 35 - CL2 C6 H3 CH2 MMe3 with M = Si and Sn have been examined in H 2O - Me0H medium oc - and 13-CDs accelerate the cleavage of the RSnMe3 compounds R=3-0106 H4 CH2 4-0106 H4 CH2 and 35 - 01 2 C6H3 CH2 There is no significant catalysis in the case of the corresponding silicon compounds