Permanganate-Pyruvic Acid Initiated Polymerization of Methacrylamide

A combined system of potassium permanganate and pyruvic acid was found to initiate radical polymerization of vinyl monomers, especially acrylamides. From kinetic investigations of the polymerization of methacrylamide, it was found that this initiator induced a radical polymerization which proceeded with an overall activation energy of 15.7 kcal/mol. The rate is given by

R_p=K[methacrylamide] ¹ [pyruvic acid]° [KMnO₄]¹ in aqueous and water-DMF mediums. In the presence of DMF the initial rate was found to decrease but the kinetic equation remained the same. The investigations were done at 35 ± 0.2°C in nitrogen.

Besides the clinical importance of pyruvic acid found in blood, urine, muscles, etc., it is a good initiator in conjunction with KMnO₄ for vinyl polymerization. It is therefore interesting to study the polymerization of methacrylamide using the KMnO₄-pyruvic acid redox couple in aqueous systems in order to find whether this system follows the same kinetic features of vinyl polymerization by a radical mechanism.     

Synthesis of fluoro derivatives of 2,4,6-triarylpyridines

A variety of fluoro-substituted 2,4,6-triarylpyridines have been prepared via the reaction of 4-picolinium 4-chlorophenacyl methylide, with a series of fluorinated α,β-unsaturated ketones in the presence of ammonium acetate in acetic acid.     

The use of ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator for the polymerization of methyl methacrylate

The thermal polymerization of methyl methacrylate [MMA] was carried out using ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator. The rate of polymerization (R_p) increases with increasing monomer and initiator concentrations; The exponent value has been computed to be 1 ± 0.02 and 0.5, respectively. The reaction was carried out at four different temperatures and the overall activation energy has been computed to be 16.01 kcal/mol. The polymerization was inhibited in the presence of hydroquinone as a radical scavanger. Kinetic studies indicates that the overall polymerization takes place by a radical mechanism.     

Preparation and Catalytic Application of Novel Water Tolerant Solid Acid Catalysts of Zirconium Sulfate/HZSM-5

Esterification of acrylic acid(AA) to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate(ZS) loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20%(mass fraction) ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.     

Semiempirical Predictions of Chemical Degradation Reaction Mechanisms of CL-20 as Related to Molecular Structure

Combining computer chemistry calculation with experimental verification is useful both in proving concepts and what is chemically possible. Computational predictions, using MOPAC quantum mechanical and classical force field mechanics, were used to investigate most likely first-tier intermediates of cyclic and cage cyclic nitramines—comparing bond lengths and angles, heats of formation, steric energy, dipole moments, solvent accessibility and electrostatic potential surfaces, partial charges, and Highest Occupied Molecular Orbitals/Lowest Unoccupied Molecular Orbitals (HOMO/LUMO) energies. Two competing modes of degradation are summarized: through addition of hydroxide ions and through addition of photo-induced free radicals. UV/VIS measured concentrations and followed the course of reactions. FTIR followed CL-20 degradation through alkali hydrolysis, where FTIR measurements verified theoretical predictions.