78186-22-8

Upstream product

• 56133-29-0 1-(4-methylbenzyl)-1,4-dihydronicotinamide 
• 81246-21-1 2-(4-Cyano-benzyl)-3,4-dihydro-isoquinolinium 
• 98-92-0 nicotinamide 
• 104-82-5 4-Methylbenzyl chloride 
• 13367-81-2 10-methylacridinium cation 

Relevant academic research and scientific papers

A classical but new kinetic equation for hydride transfer reactions

A classical but new kinetic equation to estimate activation energies of various hydride transfer reactions was developed according to transition state theory using the Morse-type free energy curves of hydride donors to release a hydride anion and hydride acceptors to capture a hydride anion and by which the activation energies of 187 typical hydride self-exchange reactions and more than thirty thousand hydride cross transfer reactions in acetonitrile were safely estimated in this work. Since the development of the kinetic equation is only on the basis of the related chemical bond changes of the hydride transfer reactants, the kinetic equation should be also suitable for proton transfer reactions, hydrogen atom transfer reactions and all the other chemical reactions involved with breaking and formation of chemical bonds. One of the most important contributions of this work is to have achieved the perfect unity of the kinetic equation and thermodynamic equation for hydride transfer reactions. The Royal Society of Chemistry.

Negative kinetic temperature effect on the hydride transfer from NADH analogue BNAH to the radical cation of N-benzylphenothiazine in acetonitrile

The reaction rates of 1-(p-substituted benzyl)-1,4-dihydronicotinamide (G-BNAH) with N-benzylphenothiazine radical cation (PTZ?+) in acetonitrile were determined. The results show that the reaction rates (k obs) decreased from 2.80 × 107 to 2.16 × 107 M-1 s-1 for G = H as the reaction temperature increased from 298 to 318 K. The activation enthalpies of the reactions were estimated according to Eyring equation to give negative values (-3.4 to -2.9 kcal/mol). Investigation of the reaction intermediate shows that the charge-transfer complex (CT-complex) between G-BNAH and PTZ ?+ was formed in front of the hydride transfer from G-BNAH to PTZ?+. The formation enthalpy of the CT-complex was estimated by using the Benesi-Hildebrand equation to give the values from -6.4 to -6.0 kcal/mol when the substituent G in G-BNAH changes from CH3O to Br. Detailed thermodynamic analyses on each elementary step in the possible reaction pathways suggest that the hydride transfer from G-BNAH to PTZ?+ occurs by a concerted hydride transfer via a CT-complex. The effective charge distribution on the pyridine ring in G-BNAH at the various stages-the reactant G-BNAH, the charge-transfer complex, the transition-state, and the product G-BNA+-was estimated by using the method of Hammett-type linear free energy analysis, and the results show that the pyridine ring carries relative effective positive charges of 0.35 in the CT-complex and 0.45 in the transition state, respectively, which indicates that the concerted hydride transfer from G-BNAH to PTZ?+ was practically performed by the initial charge (-0.35) transfer from G-BNAH to PTZ?+ and then followed by the transfer of hydrogen atom with partial negative charge (-0.65). It is evident that the present work would be helpful in understanding the nature of the negative temperature effect, especially on the reaction of NADH coenzyme with the drug phenothiazine in vivo.

Reactions of charged substrates. 4. The gas-phase dissociation of (4-substituted benzyl) dimethylsulfoniums and -pyridiniums

The relative rates for the gas-phase dissociation RX- → R- + X° of five (4-Y-substituted benzyl)-dimethysulfoniums (Y = MeO, Me, H, Cl, and NO2) and 24 (4-Y-substituted benzyl)-3′-Z-pyridiniums (complete series for Z = CN, Cl, CONH2, and H, and 4-methoxy- and 4-nitrobenzyls for Z = F and CH3CO) were measured using liquid secondary ion mass spectrometry. The Hammett plot (vs δΔG° or σ-) is linear for the sulfoniums, but plots for the four pyridinium series have a drastic break between the 4-Cl and 4-NO2 substrates. Bronsted-like plots for the pyridiniums show a strong leaving group effect only for 4-nitrobenzyls. An analysis of these linear free energy relations with supporting evidence from semiempirical computations suggests that collisionally activated pyridinium substrates dissociate by two pathways, direct dissociation and through an ion-neutral complex intermediate. Comparison of these results with results for the solution reactions of some of these compounds shows that the mechanism is different in the gas and solution phases. Sufficient experimental data are not available to assign a mechanism for dissociation to the sulfonium series, but computational results show characteristics of a direct dissociative mechanism.

Kinetics of the Reduction of 3,4-Dihydroisoquinolinium Cations by 1,4-Dihydronicotinamides

Pseudo-first-order rate constants for the reduction of 2-methyl-3,4-dihydroisoquinolinium cation (1) by 1-(X-benzyl)-1,4-dihydronicotinamides (3) display kinetic saturation at high concentrations of 1 (20percent CH3CN-80percent H2O, 25 deg C, ionic strength 1.0).Association constants for 1:1 complex formation are independent of X (1.4 +/- 0.2 M-1) and are most simply interpreted in terms of nonproductive complex formation.Pseudo-first-order rate constants for the reduction of 2-(Z-benzyl)-3,4-dihydroisoquinolinium cations (2) by 3 are linear for up to approximately 60 mM.Hammett correlations for the second-order rate constants for these reactions give ρx = -0.77 for the reduction of 2 (Z = 4-CN) by 3 and ρz = 0.83 for the reduction of 2 by 3 (X = H).Comparisons of ρx and ρz with equilibrium ρ values for closely related reactions indicate that the migrating hydrogen atom bears a charge of -0.33 and thus is clearly hydridic in character.These results are closely analogous to the conclusions of our earlier study of the 1,4-dihydronicotinamide reduction of 5-nitroisoquinolinium cations which have similar pKR+ values to those for 2.Thus similar reduction mechanisms apply to the reduction of aromatic and nonaromatic cations by 3. pKR+ values for pseudobase formation from 2 are correlated with a Hammett ρ = 1.72.The second-order rate constant for hydroxide ion attack on 2 (X = H) is fivefold larger than for the 2-benzyl-5-nitroisoquinolinium cation, although the second-order rate constant for reduction by 3 (X = H) is 23-fold greater for the latter cation than for 2 (X = H).This is interpreted in terms of a poorer "fit" between 2 and 3 in the transition state for the reduction, relative to the better "fit" between the planar 5-nitroisoquinolinium cations and 3.