Coenzyme models, 5. Addition reaction of cyanide ion to monomeric and polymeric nicotinamides. Correlation between equilibria and reaction rates

<jats:title>Abstract</jats:title><jats:p>Rate and equilibrium constants (<jats:italic>k</jats:italic><jats:sub>f</jats:sub> and <jats:italic>K</jats:italic>, respectively) for the addition of cyanideion to poly[1‐(4‐vinylbenzyl)nicotinamide chloride] (poly{1‐[4‐(3‐aminocarbonylpyridiniomethyl)phenyl]ethylene chloride}) (poly(<jats:bold>1</jats:bold>)) and a corresponding monomeric derivative of nicotinamide, 3‐aminocarbonyl‐1‐benzylpyridinium chloride (<jats:bold>2</jats:bold>), were evaluated at 30°C, in an aqueous system. The rate constant for the reaction of poly(<jats:bold>1</jats:bold>) with CN<jats:sup>−</jats:sup> at μ = 0,1 mol 1<jats:sup>−1</jats:sup> was found to be higher by a factor of 22 and the association constant by a factor of about 65, compared with those for the reaction of <jats:bold>2</jats:bold> with CN<jats:sup>−</jats:sup>. At a lower ionic strength (μ = 0,008 mol 1<jats:sup>−1</jats:sup>), the reaction parameters were markedly enhanced (108‐fold and 218‐fold, respectively). The rate enhancements in the polymeric system are attributable to the increase in the ΔS<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tex2gif-stack-1.gif" xlink:title="urn:x-wiley:0025116X:media:MACP021780114:tex2gif-stack-1" /> term. This favorable entropy term caused the deviation from the linear log <jats:italic>K</jats:italic>‐log <jats:italic>K</jats:italic><jats:sub>f</jats:sub> relationship which holds strictly for monomeric compounds.</jats:p>