Steric effects in SN2 reactions. Determination of transition state structures for the quaternization of 2-alkylpyridines and -thiazoles by a combined experimental and molecular mechanics procedure was written by Berg, Ulf;Gallo, Roger. And the article was included in Acta Chemica Scandinavica, Series B: Organic Chemistry and Biochemistry in 1983.Quality Control of 2-Isopropylpyridine This article mentions the following:
SN2 transition-state structures for the Menschutkin reactions between 2-alkylpyridines or -thiazoles and MeX (X = I, and SO3F) are calculated by the Allinger 1973 force field method. Exptl. found differences in steric energies between the quaternary iminium ions and the activated complexes are used as measures for the elevation of the position of the transition state. Estimates of the C-N distance (rC-N) in the transition state result in a 22±4% extension compared to the ground state value (1.48 Å), depending upon the transition state model used. The preferred model results in rC-N = 1.812±0.013 Å. Consistent results were obtained with nucleophiles of different geometries (pyridines and thiazoles). A change of leaving group from iodide to fluorosulfonate leads to an extension of rC-N by 0.04±0.02 Å. In the experiment, the researchers used many compounds, for example, 2-Isopropylpyridine (cas: 644-98-4Quality Control of 2-Isopropylpyridine).
2-Isopropylpyridine (cas: 644-98-4) belongs to pyridine derivatives. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1.The molecular electric dipole moment is 2.2 debyes. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid phase and 140.4 kJ·mol−1 in the gas phase. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Quality Control of 2-Isopropylpyridine