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'Solvent Effects' in keywords Facet   Publication Year 1998  [X]
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1998[X]
1Author    Piotr CysewskiRequires cookie*
 Title    Theoretical Studies on the Tautomeric Properties of Diamino-5-formamidopyrimidines  
 Abstract    The results of theoretical geometry prediction of formamidopyrimidine(fapy)-adenine and fapy-guanine tautomers are presented. Among 54 potential tautomeric structures of fapy-adenine the most stable structure corresponds to the diamino-keto isomer. The solvent effect has insignificant influence on the fapy-adenine tautom ers succession. The fapy-guanine has 172 potential isomers. There are three most stable tautom ers of this guanine derivative, which may exchange the order depending on the polarity of the environment. In vapour the most probable is the 4-enol-6-keto-diamino tautomer, while in water environm ent the 4,6-diketo-diamino isomer is dominant. A more polar solvent stabilises more polar fapy-guanine tauto­ mers. The geometric parameters and point-atomic charges corresponding to most probable tau­ tomers are also supplied. 
  Reference    Z. Naturforsch. 53c, 1027—1036 (1998); received April 20/June 19 1998 
  Published    1998 
  Keywords    Fapy-adenine, Fapy-guanine, Tautomerism, Solvent Effect 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-1027.pdf 
 Identifier    ZNC-1998-53c-1027 
 Volume    53 
2Author    Ulrich Nagel, Christoph RollerRequires cookie*
 Title    Enantioselective Catalysis, XVII [1], Enantioselective Catalytic Hydrogenation of Unfunctionalized Ketones  
 Abstract    Three diastereomeric rhodium bisphosphane complexes have been applied to asymmetric hydrogenation of unfunctionalized, non-chelating aliphatic and aromatic ketones. The ee values o f the catalysis products differ considerably for the diastereomerical catalysts. 70% ee were obtained in hydrogenating butyrophenone, and 83.7% ee for pinacoline. The results depend strongly on the solvent used. 
  Reference    Z. Naturforsch. 53b, 267—270 (1998); received January 15 1998 
  Published    1998 
  Keywords    Enantioselective Hydrogenation, Unfunctionalized Ketones, Rhodium, Salt Effect, Solvent Effect 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0267.pdf 
 Identifier    ZNB-1998-53b-0267 
 Volume    53