In organic chemistry, atoms other than carbon and hydrogen are generally referred to as heteroatoms. The most common heteroatoms are nitrogen, oxygen and sulfur. Now I present to you an article called Aromaticity and tautomerism. IV. Free energy-enthalpy correlations for protonation of pyridine bases and azine N-oxides and temperature variation of the HO and HA acidity functions, published in 1974, which mentions a compound: 14248-66-9, mainly applied to pyridine protonation thermodn; heat protonation azine; entropy protonation azine; free energy protonation azine; azine protonation; pK pyridine azine, Application In Synthesis of 3,5-Dimethyl-4-nitropyridine 1-oxide.
Addnl. data considered in abstracting and indexing are available from a source cited in the original document. Thermodn. parameters for the protonation of 9 weakly basic pyridines and 9 azine N-oxides were obtained from pKa measurements at 25, 40, 60, 80, and 90°. Linear ΔH°-pKa correlations were found. The temperature variations of the H0 and HA acidity functions were examined
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Reference:
Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem