22-Sep News Awesome Chemistry Experiments For 108-47-4

Because enzymes can increase reaction rates by enormous factors and tend to be very specific, typically producing only a single product in quantitative yield, they are the focus of active research. name: 2,4-Dimethylpyridine

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Measurements leading to the calculation of ideal-gas thermodynamic properties at p = p0 = 101.325 kPa are reported for the six dimethylpyridines (Chemical Abstract registry numbers: 2,3-dimethylpyridine <583-61-9>; 2,4-dimethylpyridine <108-47-4>; 2,5-dimethylpyridine <589-93-5>; 2,6-dimethylpyridine <108-48-5>; 3,4-dimethylpyridine <583-58-4>; and 3,5-dimethylpyridine <591-22-0>).Vapor pressures were measured for each compound by comparative ebulliometry for the pressure range 2 kPa to 270 kPa.Two-phase (liquid + vapor) heat capacities were measured with a differential scanning calorimeter (d.s.c.), and saturation heat capacities Csat,m were derived.Densities for the liquid phase of 2,3-dimethylpyridine and 2,6-dimethylpyridine were measured with a vibrating-tube densitometer.The critical temperature Tc was determined experimentally for each compound by d.s.c., and the critical pressure and critical density were derived from fitting procedures.Enthalpies of vaporization were calculated from the experimental measurements.Entropies and enthalpy increments by adiabatic heat-capacity calorimetry, published recently by this research group, and literature values for the energy of combustion were combined with the present results to derive entropies, enthalpy increments, and Gibbs free energies of formation for the ideal gas at p = p0 = 101.325 kPa for temperatures between T = 250 K and T ca. 0.95*Tc.Barriers to methyl-group rotation for the ortho-substituted compounds are estimated and compared with literature values for 1,2-dimethylbenzene.

Because enzymes can increase reaction rates by enormous factors and tend to be very specific, typically producing only a single product in quantitative yield, they are the focus of active research. name: 2,4-Dimethylpyridine

Reference：
Chiral nitrogen ligands in late transition metal-catalysed asymmetric synthesis—I. Addressing the problem of ligand lability in rhodium-catalysed hydrosilations,
Nitrogen-Containing Ligands for Asymmetric Homogeneous and Heterogeneous Catalysis