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Selective Reaction (selective + reaction)
Selected AbstractsHighly Selective Reaction of ,-Halo-,,,-unsaturated Esters with Ketones or Aldehydes Promoted by SmI2: An Efficient Alternative Access to Baylis,Hillman Adducts.CHEMINFORM, Issue 43 2005Jose M. Concellon Abstract For Abstract see ChemInform Abstract in Full Text. [source] Electrospray ionization mass and tandem mass spectra of a series of N -pyrazolylmethyl and N -triazolylmethyl N -phenylpiperazines: new dopaminergic ligands with potential antipsychotic propertiesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2005Leonardo S. Santos Abstract Recently, two analogous series of N -pyrazolylmethyl and N -triazolylmethyl N -phenylpiperazines have been prepared and found to be potential antipsychotic drugs acting as new selective ligands of the dopamine D2 receptor. Herein we report a systematic study of their high-resolution electrospray ionization mass and tandem mass spectra in which the main dissociation routes of their protonated molecules are determined and rationalized. The ESI-MS/MS data is very characteristic for both series allowing straightforward isomeric differentiation. A single and dominant fragment ion for the pyrazole series and four major fragment ions for the triazole series are useful for selective reaction MS monitoring of these potential drugs in biological fluids. Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis and characterization of catalytic nanoporous carbon membranesAICHE JOURNAL, Issue 1 2001Michael S. Strano A method is reported for the synthesis of nobel catalyic nanoporous carbon membranes. Defect-free, nanoporous carbon films of 12.5,,m average thickness containing a dispersion of Ptx were synthesized on macroporous stainless-steel supports. Ideal gas selectivities for the catalytic membranes were simliar to those of inert nanoporous carbon membranes with He,N2=58.6 and O2N2=4.9. The selective hydrogenation of monoolefins (propylen, l-buiene, isobutylene) was used to probe the shape-selective catalytic proerties nad the transport selectivities of the membranes. The results were modeled using the linear regime of coupled sdsorption, transport and rection in the membrane. Model regression yielded 14.9, 19.7. and 18.4 kJ/mol for the activation energies of permeation for propylene, isobutylene, and l-butene, respectively. The system demonstrated selective reaction and transport favoring propane production with selectiveity ratios of 28.9:3.2.I for propane:n-butane:isobutane at 125°C. [source] Well-defined complex macromolecular architectures by anionic polymerization of styrenic single and double homo/miktoarm star-tailed macromonomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2008Paraskevi Driva Abstract Styrenic single and double star-tailed macromonomers were synthesized by selective reaction of living homo/miktoarm stars with the chlorosilane groups of 4-(chlorodimethylsilyl)- and 4-(dichloromethylsilyl)styrene, respectively. The in situ anionic homopolymerization of macromonomers with sec -BuLi and copolymerization with butadiene and styrene, led to single/double homo/miktoarm star-tailed molecular brushes and combs, as well as a block copolymer consisting of a linear polystyrene chain and a double miktoarm (PBd/PS) star-tailed brush-like block. Molecular characterization by size exclusion chromatography, size exclusion chromatography/two-angle laser light scattering, and NMR spectroscopy, revealed the high molecular/compositional homogeneity of all intermediate and final products. These are only a few examples of the plethora of complex architectures possible using the above macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1826,1842, 2008 [source] Alternating poly(ester amide)s from succinic anhydride and ,,,-amino alcohols: synthesis and thermal characterization,,POLYMER INTERNATIONAL, Issue 10 2003Thomas Fey Abstract Alternating poly(ester amide)s 6a,e from succinic anhydride and ,,,-amino alcohols H2N,(CH2)x,OH (x = 2,6) 2a,e were obtained in two steps: ,-carboxyl-,-hydroxy amides 3a,e were prepared from the starting materials in a highly selective reaction, followed by a polycondensation reaction. 1H and 13C NMR analyses of the poly(ester amide)s clearly reveal the alternating microstructure. The poly(ester amide)s with homologous ,,,-amino alcohols H2N,(CH2)x,OH (x = 2,6) are semi-crystalline materials, their melting points show the odd/even effect observed for [n]-polyamides and [n]-polyurethanes. Heating the poly(ester amide)s 6a,e yields the corresponding N -(hydroxyalkyl) imides 4a,e with no trace of cyclic ester amides. Theoretical calculations revealed that the cyclic ester amides 5a,e are clearly richer in energy than the isomeric N -(hydroxyalkyl) imides. These results show that cyclic ester amides can not be prepared from N -(hydroxyalkyl) imides by ring-enlargement reactions. Copyright © 2003 Society of Chemical Industry [source] | |||||||||||||