A review of proton transfer reactions between various carbon-acids and amine bases in aprotic solvents

1,4‐Diazabicyclo[2.2.2]octane (DABCO) as an Efficient Reagent for the Synthesis of Isoxazole Derivatives from Primary Nitro Compounds and Dipolarophiles: The Role of the Base

“…[42] A proton transfer process proceeds across several stages, chiefly: neutral H-bonded complex, H-bonded ion-pair, solvent separated ion pair, separated free ions. "Which particular intermediate or product species occur in detectable quantities will depend on the reacting donor-acceptor pair and the solvent".…”

“…"Which particular intermediate or product species occur in detectable quantities will depend on the reacting donor-acceptor pair and the solvent". [42] Thus, the complete proton transfer occurs in dissociating solvents (water, MeCN, DMSO) and is measured by the pK HB +. The ion pair basicity refers to the equilibrium between the base and the acid with the Hbonded ion pair.…”

Equilibrium and kinetic study of the proton transfer reactions between nitroalkanes and strong organic bases — phosphazenes in tetrahydrofuran solvent

“…Initially, it was believed that steric hindrance leads to increased primary deuterium kinetic isotope effects by making the energetic barrier steeper [19,20] or by desolvation of the transition state [15]. However, there are examples of kinetic isotope effects insensitive to the bulk of substituent or even decreasing with steric hindrance either on C-acid or on the base [15]. Phosphazenes are more sterically hindered than DBU, TBD or MTBD.…”

“…These results show that the steric factor and ordering effects in forming the transition state play an important role, confirmed by negative and relatively large entropies of activation: ∆S ‡ = -149.7, -176.5, -178.7, -227.8 J mol -1 K -1 . The reactions between nitroalkanes with different steric hindrance and classic nitrogenous bases such as amidines or guanidines in acetonitrile and tetrahydrofuran have been disscussed previously [12][13][14][15].…”

Kinetic and equilibrium study of the deprotonation of 4-nitrophenyl[bis(ethylsulphonyl)]methane by organic bases in acetonitrile in the presence of common cation BH+ and tetrabutylammonium perchlorate

“…The complex mechanism of the proton transfer reaction and the variety of carbon acids with respect to their strength, type of electron withdrawing group and steric hindrance in the reaction center give the opportunity to evaluate the factors influencing rate constants and the mechanism of reaction [1][2][3][4]. Two groups of Brønsted acids are commonly distinguished.…”