The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Kak-shan Shia - One of the best experts on this subject based on the ideXlab platform.
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Autoxidative annulation cascade of the α-cyano β-TMS-capped alkynyl Cycloalkanone system.
Organic letters, 2011Co-Authors: Ying‐chieh Wong, Min-tsang Hsieh, Prashanth K. Amancha, Chih-lung Chin, Cheng-feng Liao, Chun-wei Kuo, Kak-shan ShiaAbstract:The autoxidative annulation cascade promoted by an α-cyano β-TMS-capped alkynyl Cycloalkanone system under catalysis with pyridine in one oxygen atmosphere has proven to be highly viable. On the ba...
Ying‐chieh Wong - One of the best experts on this subject based on the ideXlab platform.
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Autoxidative annulation cascade of the α-cyano β-TMS-capped alkynyl Cycloalkanone system.
Organic letters, 2011Co-Authors: Ying‐chieh Wong, Min-tsang Hsieh, Prashanth K. Amancha, Chih-lung Chin, Cheng-feng Liao, Chun-wei Kuo, Kak-shan ShiaAbstract:The autoxidative annulation cascade promoted by an α-cyano β-TMS-capped alkynyl Cycloalkanone system under catalysis with pyridine in one oxygen atmosphere has proven to be highly viable. On the ba...
El-halabi, Nabil M. - One of the best experts on this subject based on the ideXlab platform.
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Reaction of nitrilimines with keto-alkoxycarbonyl-hydrazones: Synthesis of substituted 1, 2, 4-triazoles and heterocyclic spiro compounds
'Asian Journal of Chemistry', 2002Co-Authors: Awad, Boshra M, Abdel-rahman S. Ferwanah, Awadallah, Adel M., El-halabi, Nabil M.Abstract:Hydrazonoyl halides (1) react with alkanone and Cycloalkanone alkoxycarbonylhydrazones (3) to give the cycloaddition products 4, 5-dihydro-1, 2, 4-triazoles (7a-h) rather than the tetrazine cyclocondensation products. Reaction of (7c, d) with hydoxylamine gave the corresponding oximes (8c, d) of these heterocycles
Meka Srinivasarao - One of the best experts on this subject based on the ideXlab platform.
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Microwave assisted solvent free synthesis of α,ά-bis (arylidene) Cycloalkanones by sulfated zirconia catalyzed cross aldol condensation of aromatic aldehydes and Cycloalkanones
Journal of Industrial and Engineering Chemistry, 2012Co-Authors: Kirat Rawal, Manish Mishra, Manish Dixit, Meka SrinivasaraoAbstract:Abstract The catalytic application of sulfated zirconia as solid Bronsted acid catalyst was explored for cross aldol condensation reactions (Claisen Schmidt reaction). The synthesized catalyst was highly active for solvent free synthesis of α,ά-bis(arylidene)Cycloalkanones by cross aldol condensation of aromatic aldehydes with Cycloalkanones. The microwave assisted synthesis resulted increased yields of the products (79–99%) at significantly lower reaction temperature (120–140 °C) and reaction time (20 min) as compared to the synthesis by thermal heating (63–96% yield at 170 °C after 4 h). The microwave irradiation afforded selectively cross aldol products. The catalyst could be easily regenerated and reused several times with similar efficiency.
Palaninathan Kannan - One of the best experts on this subject based on the ideXlab platform.
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Photoreactive main chain liquid crystalline polyesters containing oxadiazole and bis(benzylidene) Cycloalkanone units
Journal of Polymer Science Part A: Polymer Chemistry, 2008Co-Authors: Rathinam Balamurugan, Palaninathan KannanAbstract:Photoreactive main chain liquid crystalline polyesters containing oxadiazole and bis(benzylidene)Cycloalkanone moieties were synthesized and characterized by structural, thermal, mesomorphic, and optical measurements. The bis(benzylidene) Cycloalkanone chromophores in the main chain can constitute both as a mesogen and photoreactive center, whereas 1,3,4-oxadiazole is a well-known fluorophore. The thermal properties of polymers were found to be inversely proportional not only to the spacer length but also to ring-size of Cycloalkanones. Hot stage polarized optical microscopic investigations displayed enantiotropic nematic liquid crystalline phases and development of grainy to schlieren textures depends on the length of flexible spacer in the polymer backbone which was in accordance with DSC analysis. Both photoisomerization and photodimerization are observed from the absorption spectra and discussed. The fluorescence spectra in solution state at various concentrations showed that the polymers show blue-emission maxima and the Stokes shifts being 48–49 nm. The energy transfer occurred when increasing the concentration of the solution. The band gap energies calculated from the absorption spectra are in the range of 3.17–3.41 eV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5760–5775, 2008
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Novel photo‐crosslinkable liquid crystalline polymers containing vanillylidene Cycloalkanones and azobenzene units
Liquid Crystals, 2008Co-Authors: D. Jayalatha, Rathinam Balamurugan, Palaninathan KannanAbstract:Two series of novel liquid crystalline photo‐crosslinkable bis(vanillylidene‐azobenzene) Cycloalkanone containing polymers, namely poly(vanillylidene alkyloxy‐4,4′‐azobenzenedicarboxylic ester)s, have been synthesised from bis[m‐hydroxyalkyloxy(vanillylidene)Cycloalkanone] (m = 6, 8, 10) with azobenzene dicarbonylchloride by solution polycondensation method at ambient temperature. Polymers with varying spacer lengths have been synthesised and characterised by spectroscopic techniques. These variations have been correlated with the thermal properties and transition temperatures. Thermal transitions were analysed by differential scanning calorimetry (DSC) and the mesophases were identified by hot stage optical polarised microscopy (HOPM). All of the polymers were found to exhibit liquid crystalline properties. Transition temperatures were observed to decrease with increasing spacer length. The thermogravimetric analysis reveals that all of the polymers were stable up to 280°C undergo two‐stage decomposition...
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Synthesis and Characterization of Benzylidene and Azobenzene Based Photochromic Liquid-Crystalline Polymers DEVASWITHIN JAYALATHA RATHINAM BALAMURUGAN
2007Co-Authors: Palaninathan KannanAbstract:Abstract: Two series of novel thermotropic main chain liquid crystalline polymers containing photocross-linkable chalcone and photoisomerizable azobenzene moieties were synthesized from bis[4-(m-hydro-xyalkoxy)benzylidene]Cycloalkanones [m = 6,8,10] with 4,4-azobenzene dicarbonylchloride. The chemi-cal structure of the monomers and polymers were confirmed by spectral techniques. The mesophase prop-erties were investigated using hot stage optical polarized microscopy and differential scanning calorimetry. All the polymers exhibited liquid crystalline properties. The thermogravimetric analysis data revealed that the polymers were stable up to 220 C and underwent two-stage decomposition. Photocrosslinking prop-erty of the polymers was investigated using UV spectroscopy. The cyclopentanone containing polymers showed faster photocrosslinkability than that of their cyclohexanone counterpart. In addition to the pho-tocrosslinkability of Cycloalkanone units, the azo moiety displayed E-Z (trans-cis) isomerization in the polymer backbone
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studies on photo crosslinkable polyphosphoramide esters containing divanillylidene Cycloalkanone units
Polymer International, 1996Co-Authors: Palaninathan Kannan, S. C. MurugavelAbstract:Two series of photo-crosslinkable polyphosphoramide esters were synthesized from 2,5-bis(4-hydroxy-3-methoxy benzylidene)cyclopentanone and 2,6-bis(4-hydroxy-3-methoxy benzylidene)cyclohexanone with various N-arylphosphoramide dichlorides by interfacial polycondensation using hexadecyl trimethylammonium bromide as phase transfer catalyst at ambient temperature. The resulting polymers were characterized by inherent viscosity, Fourier transform infra-red, 1 H and 13 C nuclear magnetic resonance spectroscopy. The thermal stability of the polymers synthesized was evaluated by thermogravimetric analysis. These polymers were studied for their photo-chemical reactions. The divanillylidene cycloakanone groups in the polymer chain function as photo-active centres. Crosslinking proceeds via 2π + 2π cycloaddition reaction of the divanillylidene Cycloalkanone moieties. The rate of crosslinking decreases with increase in the size of the Cycloalkanone ring, while the thermal stability increases with increase in the size of the Cycloalkanone ring.
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Studies on photo‐crosslinkable polyphosphoramide esters containing divanillylidene Cycloalkanone units
Polymer International, 1996Co-Authors: Palaninathan Kannan, S. C. MurugavelAbstract:Two series of photo-crosslinkable polyphosphoramide esters were synthesized from 2,5-bis(4-hydroxy-3-methoxy benzylidene)cyclopentanone and 2,6-bis(4-hydroxy-3-methoxy benzylidene)cyclohexanone with various N-arylphosphoramide dichlorides by interfacial polycondensation using hexadecyl trimethylammonium bromide as phase transfer catalyst at ambient temperature. The resulting polymers were characterized by inherent viscosity, Fourier transform infra-red, 1 H and 13 C nuclear magnetic resonance spectroscopy. The thermal stability of the polymers synthesized was evaluated by thermogravimetric analysis. These polymers were studied for their photo-chemical reactions. The divanillylidene cycloakanone groups in the polymer chain function as photo-active centres. Crosslinking proceeds via 2π + 2π cycloaddition reaction of the divanillylidene Cycloalkanone moieties. The rate of crosslinking decreases with increase in the size of the Cycloalkanone ring, while the thermal stability increases with increase in the size of the Cycloalkanone ring.
