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Coenzyme models. IV. Effect of polymer micelles on rate and equilibrium of addition of cyanide ion to N ‐substituted 3‐carboxamidopyridinium ions
Author(s) -
Shinkai Seiji,
Kunitake Toyoki
Publication year - 1976
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1976.360150609
Subject(s) - chemistry , micelle , polyelectrolyte , aqueous solution , bromide , ionic strength , polymer , cyanide , reaction rate constant , ion , polymer chemistry , inorganic chemistry , organic chemistry , kinetics , physics , quantum mechanics
The water‐soluble poly(1‐vinyl‐2‐ethylimidazole) quaternized with ethyl bromide and lauryl bromide was prepared; lauryl group content, 8.8 mol% (L‐9), 28.9 mol% (L‐29), and 40.9 mol% (L‐41). The λ max value of methyl orange near 460 nm shifted to shorter wavelengths (417–433 nm) in the aqueous solution of L‐29 and L‐41, and the intrinsic viscosity of L‐29 was more than ten times smaller than that of L‐9. The rate and equilibrium constants ( k ƒ and K ) for addition of cyanide ion to the N ‐substituted 3‐carboxamidopyridinium ions were studied at 30°C, where N ‐substituents employed were n ‐propyl, n ‐hexyl, benzyl, 2,6‐dichlorobenzyl, and n ‐lauryl. The kinetic parameters for n ‐lauryl‐3‐carboxamidopyridinium were markedly increased in the presence of L‐29 and L‐41 and with increasing polymer concentrations (84‐fold for k ƒ and 7800‐fold for K ), especially at low ionic strength, whereas L‐9 decelerated the addition reaction. These distinct behaviors mean that L‐29 and L‐41 are classified as micellelike polymers and L‐9 as a polyelectrolytelike polymer. However, L‐29 depressed the rate of the forward reaction for benzyl‐3‐carboxamidopyridinium, acting like a simple polyelectrolyte. Therefore, the polymer micelle can provide both the microenvironments characteristic of polyelectrolytes and micelles, depending on the hydrophobicity of substrates.