Iranian Journal of Chemistry and Chemical Engineering
Year:1997 | Volume:16 | Issue:1|Papers Count:10

A new synthesis of Alpha-hydroxycarboxylates and 2-hydroxybenzoates based on the reaction of acetonides of alpha-hydroxycarboxylic acids and 2-hydroxybenzoic acid with sodium alkoxides in the corresponding alcohols as solvent is described. in general, decreasing the steric hindrance of the reactants and increasing the boiling points of alcohols increased the yields and decreased the required time for the reactions.

Aminocarboxylic acids, such as 2-aminobenzoic acid, react easily with [Ir(COD)(PMe3)(3)]Cl, (COD= 1,5-cyclooctadiene), in THF to produce hydridoaminocarboxylato iridium(III) complexes in high yields, These octahedral complexes are formed via oxidative addition reaction of the O-H bond of the carboxylic group with the central metal. The starting iridium(I) complex losses the COD molecule, the chloride is coordinated to the metal and the phosphine groups take a meridional position in the final products which are characterized by H-1, C-13 and P-31 NMR spectroscopies.

The catalytic oxidation of toluene to benzoic acid in the liquid phase has been studied in an un-stirred tank reactor. Low concentration of acetic acid was added in order to increase the solubility of the catalyst in toluene. The dependence of the rate of reaction on the concentration of toluene catalyst and oxygen pressure was studied It has been suggested that liquid phase oxidation of toluene to benzoic acid primarily is a diffusion controlled reaction and the order of reaction with respect to oxygen shifts to lower values by stirring.

Anthralin anti some of its derivatives have implied antipsoriatic effect in clinical and pharmaceutical studies. Anthralin irs synthesised by different strategies. In this work rye report the synthesis of "OEHA" as a precursor of another biological active compound.

A systematic study on the electrochemical behaviour of the S-derivatives of 2-amino cyclopentene-1-dithiocarboxylic acid (ACDA) has been carried out in aqueous ethanolic solutions by means of polarography, coulometry and voltammetry. All the compounds studied exhibited a well defined anodic wave corresponding to a diffusion controlled process. Controlled potential coulometry gave n=1 per mole for the anodic waves of the S-methyl and N-methyl S-methyl derivatives of ACDA, while for the dimer of ACDA a two electron oxidation wave was obtained.

The complexation reactions between methylthymol blue (MTB) and Co2+, Ni2+, Cu2+, Zn2+ and Pb2+ ions have bean studied in different water-methanol mixtures at pH 4.45 and 25 degrees C by a spectrophotometric technique. The stepwise stability constants of the resulting 1:1 and 2:1 (metal ion to ligand) complexes were determined from the absorbance-mole ratio data. It was found that the overall stability constants of the complexes formed increase in the order Zn2+ < Co2+

2-monobromomethyl 1,4-dihydropyridines is selectively synthesized by bromination of the parent compound by 1.1 equivalents of pyridinium bromide perbromide in dichloromethane/pyridine at -20 degrees C. The same reagent in dichloromethane at 0 degrees C produce the 2,6-bis(bromomethyl) 1,4-dihydropyridines.

The 2-mono and 2,6-disubstituted methyl-1,4- dihydropyridines were synthesized by reaction of morpholine, thiophenol, 8-hydroxyquinoline, 2-naphthol and 2-mercapto-1-methyl imidazole with the 2-mono bromo and 2,6-dibromo-1,4-dihydropyridines.

Material balance around process has been conducted by using mixer output equations. A method based on Mason"s theory has been proposed to develop mixer output equations.

Flotation is the most important process for concentrating mineral ores. This process may occur in any vessel such as column flotation, which has been used widely during the last decade and the conventional flotation cells. The effect of superficial feed velocity on the copper recovery was investigated using pilot-scale column flotation of "Sarcheshmeh Copper Complex". The results were compared with the conventional flotation cell data. It was reveled that for coarse particles (d(80)=90 mu m) this column could not be used instead of cells and rougher cells, but for small particles (d(80)=44 mu m) it could, For coarse particles, recovery curve demonstrated a maximum with increase in feed rate. However a minimum was observed for fine particles.