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'Tautomerism' in keywords Facet   section ZfN Section C  [X]
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1998 (1)
1976 (1)
1Author    Jerzy Sepiol, Zygmunt Kazimierczuk, David ShugarRequires cookie*
 Title    Tautomerism of Isoguanosine and Solvent-Induced Keto-Enol Equilibrium  
 Abstract    Ultraviolet and infrared absorption spectroscopy, in aqueous and non-aqueous media, have been employed to study the tautomerism of 9-substituted isoguanines, including the nucleoside iso­ guanosine. With the aid of a series of model compounds, it was shown that 9-substituted isogua­ nines, and isoguanosine, in aqueous medium are predominantly in the form N (1) H,2-keto-6-amino. In dioxane solution the tautomeric equilibrium is shifted in the direction of the enol form. The shift towards this form is accentuated for those analogues in which the exocyclic amino group is methylated. 
  Reference    (Z. Naturforsch. 31c, 361 [1976]; received May 3 1976) 
  Published    1976 
  Keywords    Isoguanine Analogues, Isoguanosine, Tautomerism, Tautomeric Equilibrium, Solvent Polarity 
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 TEI-XML for    default:Reihe_C/31/ZNC-1976-31c-0361.pdf 
 Identifier    ZNC-1976-31c-0361 
 Volume    31 
2Author    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