Yogesh S. Patel

Effect of liophilicity of catalyst in cyclic carbonate formation by transesterification of polyhydric alcohols

The effect of catalyst liophilicity is shown in cyclic carbonate formation by transesterification. 1,3-Dichlorodistannoxanes as liophilic transesterification catalysts facilitated cyclic carbonate formation from corresponding 1,2-diols and diethyl carbonate in continuous fashion without isolation of catalyst. Thus 0.5 mol% of catalyst could produce 1,2-glycerol carbonate quantitatively in 2 h with multiple recyclability. The product formed during the reaction was almost quantitative and did not require further purification. Isolation of catalyst at any stage showed retention of its activity and identity.

Synthesis, spectral, magnetic, thermal and biological aspects of pyromellitic dianhydride based co-ordination polymers

A ligand, 2, 5-bis (4-nitrophenylcarbamoyl) terephthalic acid (bnpctpa) was synthesized by using dianhydride of 1, 2, 4, 5-benzenetetracarboxylic (pyromellitic dianhydride–abbreviated PMDA) with 4-nitro aniline. Novel Co-ordination polymers of this bis-ligand were prepared with Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) metal salts. The co-ordination polymers and parent ligand were characterized by elemental analysis, spectral studies, thermogravimetry, number-average molecular weights (Mn), diffuse reflectance spectral studies and magnetic susceptibilities. The biological activity of all the samples has also been monitored against plant pathogens.

Tuning catalyst solubility in CO2 by changing molar volume

Abstract Poor-solvating property of supercritical carbon dioxide (scCO2) has been a great challenge, which limits the use of CO2 as a common “green” solvent. The present report describes that by increasing molar volume (v) and lowering the melting temperature, which lowers cohesive energy density or solubility parameter (δ), it is possible to increase the solubility of metal-based catalysts in scCO2 without using costly fluorinated or tailor-made CO2-philic modifications. We have studied various chlorodistannoxanes (1) and Cu–β-diketonates (2) to support our views. The study of bio-diesel production and transesterification of hindered esters using 1 in scCO2 shows a 2–8-folds rate enhancement coupled with an easier catalyst and product separation than that in organic solvents. The methodology, which works at least within the range of Van der Waals sphere of interactions, can be useful to solubilizing the molecules in scCO2 and carries great opportunity in catalysis as well as in separation science.

Furan-maleimide thermoplast-thermoset merged polyimides

Novel thermoplast–thermoset merged polyimide system has been developed via Diels-Alder intermolecular reaction of bisfuran A namely, 2,5-bis(furan-2-ylmethyl carbamoyl)terephthalic acid with a series of bismaleimides B1–5 containing aliphatic and alicyclic groups in the main chain viz., B1: 1,2–bismaleimido ethane, B2: 2–methyl–1,5–bismaleimido pentane, B3: 1,6–bismaleimido hexane, B4: 2,2,4–trimethyl 1,6–bismaleimido hexane, B5: isophorone bismaleimide. The intermediate Furan—maleimide Diels-Alder adducts C1–5 were aromatized and imidized (i.e. cyclized) through carboxylic and amide groups to afford thermoplast-thermoset merged polyimides D1–5. Synthesized polyimides were characterized by elemental analysis, spectral features, number average molecular weight (Mn¯

Synthesis of thermoplastic–thermosetting merged polyimides by use of the Diels–Alder reaction

\overline{\mathrm{Mn}}

Thermoplastic-Thermosetting Merged Polyimides Derived from Furan-Maleimide

) and thermal analyses. Bulk polymerization was also carried out. Proof of structure was based mainly on a comparison of infrared spectra of polyimides with those of the corresponding model compound 4 prepared from phthalic anhydride and furan–2yl–methanamine in the similar way. FTIR spectral features of polyimides D1–5 were quite identical with the model compound 4. The ‘in situ’ void–free glass fiber reinforced composites GFRC1–5 were prepared and characterized by mechanical, electrical and chemical properties. The ‘in situ’ produced PIs show good adhesion to glass fibers. All the composites showed good mechanical and electrical properties and good resistance to organic solvents and mineral acids.

Methanol assisted selective formation of 1,2-glycerol carbonate from glycerol and carbon dioxide using nBu2SnO as a catalyst

Novel coordination polymers of 2,5-bis(naphthalen-1-ylcarbamoyl)terephthalicacid were prepared by using various metal salts viz. Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) and characterized by physicochemical, thermogravimetric and spectroscopic techniques. Electronic spectral analysis and magnetic measurement studies were taken into account for the geometry of coordination polymers. Polymeric properties have also been carried out. Compounds were evaluated for their antibacterial activity against Gram-positive and Gram-negative bacterial strains. Growth inhibition was compared with the standard drug ciprofloxacin. Antifungal activity was also carried out against different fungal strains. The antifungal drug, ketoconazole was used as a positive control.

Synthesis, characterization, and biological activity of coordination polymers derived from pyromellitic dianhydride

Novel thermoplastic–thermosetting merged polyimides (PIs) have been developed by Diels–Alder (DA) intermolecular reaction of the bisfuran 2,5-bis(furan-2-ylmethylcarbamoyl)terephthalic acid A with a series of bismaleimides, viz., m,m′-dimethyl p,p′-dimaleimidobiphenyl (B1), m,m′-dimethoxy p,p′-dimaleimidobiphenyl (B2), 1,1′-bis(4-maleimidophenyl)cyclohexane (B3), and 2,2′-bis-[4-(4-maleimidephenoxy)phenyl]propane (B4). The intermediate DA adducts obtained, C1–4, were aromatized and imidized (i.e. cyclized) through the carboxyl and amide groups to afford thermoplastic–thermosetting merged PIs D1–4. Bisfuran A was prepared by condensation of pyromellitic dianhydride with furan-2-ylmethanamine and duly characterized. Synthesized DA adducts and PIs were characterized by use of elemental analysis, spectral features, number average molecular weight, degree of polymerization, and thermal analysis. To facilitate the correct structure assignment and to verify the identities of the DA adducts and PIs, a model compound 4 was prepared in a similar way from phthalic anhydride and furan-2-ylmethanamine. FT-IR spectral features of PIs D1–4 were compared with those of model compound 4 and found to be identical. Glass fiber-reinforced composites GFRC1–4 were prepared from this system and characterized by chemical, mechanical, and electrical analysis. All the composites had good mechanical, electrical, and thermal properties and good resistance to organic solvents and mineral acids.