Nicotinamide. Ultraviolet Absorption Spectra and Dissociation Constants.

1951 ◽  
Vol 55 (2) ◽  
pp. 173-180 ◽  
Author(s):  
H. H. G. Jellinek ◽  
Margaret G. Wayne
Keyword(s):  
Absorption Spectra ◽  
Dissociation Constants ◽  
Ultraviolet Absorption

Ultraviolet Absorption Spectra and Dissociation Constants of Diamino-1,3,5-triazines

2002 ◽  
Vol 67 (4) ◽  
pp. 429-438 ◽  
Author(s):  
Rafael Pérez ◽  
Rafael Marín Galvín ◽  
José M. Rodríguez Mellado
Keyword(s):  
Normal Distribution ◽  
Absorption Spectra ◽  
Dissociation Constants ◽  
Ultraviolet Absorption ◽  
Amino Groups ◽  
Individual Bands ◽  
Ring Nitrogen ◽  
Log Normal ◽  
The Individual ◽  
Log Normal Distribution

This paper presents ultraviolet absorption spectra of two diamino-1,3,5-triazines, namely 1,3,5-triazine-2,4-diamine (DT) and 6-chloro-1,3,5-triazine-2,4-diamine (ClDT). The spectra were fitted to the log-normal distribution. In the more energetic zone of the spectrum both compounds presented common bands, placed around 204-205 and 223-226 nm (depending on the pH of the medium). At higher wavelengths the spectra were different, with bands appearing in the range 235-267 nm. From variations of the maximum absorbances of the individual bands, the pKb values 3.5 ± 0.2 and 1.2 ± 0.1 were obtained for protonation of the ring nitrogen placed between the amine radicals of DT and ClDT, respectively, and 9.35 ± 0.2 and 11.5 ± 0.1 for dissociation of the amino groups of DT and ClDT, respectively.

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