Abstract: Aseries of 3-N-substituted 1, 4-dihydronicotinamide model compounds(1_4)were synthesized.The second order rate const ants of The apparent hydride transfer reactions of these NAD (P)Hmodels with 5-nit roisoquinolinium ion were measured.The redox pot entials were also determined.The results show ed that The 3-acyl group of The dihydropy ridine ring could on one hand delocalize The electrons on The ring nit rogen, and on The other hand the part ially negat ively charged 3-acy loxygen could cause two types of Electrostatic stabilization to the reaction transition state, i.e.electrostatic stabilizing interaction with the partialy positively charged 4 carbon with in The model molecule, and intermolecular electrostatic stabilizing interaction with The positively charged subst rate.The Electronic ef fectof The 3carbonyl group on The kinetic reactivities of The NAD(P)Hmodels in relation to their respective Thermodynamic parameters is rationalized by combination of Both effects.

Key words: NAD(P)H models, 5-Nitroisoquinoliniumion, Structure reactivity relationship, Kinetic reactivity