The lipophilicity and hydrogen bond strength of pyridine-N-oxides and protonated pyridine-N-oxides was written by Abraham, Michael H.;Honcharova, Lesya;Rocco, Silvana A.;Acree, Jr William E. Jr.;De Fina, Karina M.. And the article was included in New Journal of Chemistry in 2011.Application In Synthesis of 3,5-Dimethylpyridine 1-oxide This article mentions the following:
Water-solvent partition coefficients for 4-nitropyridine-N-oxide have been determined in six solvent systems, and solubilities measured in water and 37 solvents. The combined data are used to obtain Abraham descriptors for 4-nitropyridine-N-oxide as follows: E = 0.934, S = 1.92, A = 0.21, B = 0.76, V = 0.9082 and L = 5.246; literature data on partition coefficients were used to calculate descriptors for 11 other pyridine-N-oxides as well as quinoline-N-oxide and isoquinoline-N-oxide. In all cases, the N-oxides were shown to be stronger hydrogen bond bases than the corresponding pyridines, thus leading to a decrease in lipophilicity. An unexpected observation is that of the hydrogen bond acidity of the N-oxides due, we suggest, to the pos. nitrogen atom in the moiety N(+) → O(-). This leads to an even sharper decrease in the N-oxide lipophilicity in non-polar solvents. We have also used literature data to determine the 1 : 1 hydrogen bond basicity, βH2, of a number of pyridine-N-oxides; again, this basicity is significantly larger than that of the corresponding pyridines. Protonation of pyridine-N-oxides removes all hydrogen bond basicity (B = 0.00), but the protonated compounds are strong hydrogen bond acids. For protonated pyridine-N-oxide itself, E = 0.514, S = 2.62, A = 1.51, B = 0.00, V = 0.7555 and the ionic descriptor J+ = 0.894; protonated 4-nitropyridine-N-oxide with A = 2.05 is a very strong hydrogen bond acid indeed. In the experiment, the researchers used many compounds, for example, 3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8Application In Synthesis of 3,5-Dimethylpyridine 1-oxide).
3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8) belongs to pyridine derivatives. Pyridines are an important class of heterocycles and occur in polysubstituted forms in many naturally occurring biologically active compounds, drug molecules and chiral ligands. Reduced pyridines, namely tetrahydropyridines, dihydropyridines and piperidines, are found in numerous natural and synthetic compounds. The synthesis and reactivity of these compounds have often been driven by the fact many of these compounds have interesting and unique pharmacological properties. Application In Synthesis of 3,5-Dimethylpyridine 1-oxide