Oxy- and Amino-Pyridines

The three oxy-pyridines are subject to tautomerism involving hydrogen interchange between oxygen and nitrogen, but with a signihcant difference between a- and y- on the one hand and P-isomers on the other. 

Under all normal conditions, a- and y-isomers exist almost entirely in the carbonyl tautomeric form, and are accordingly known as pyridones the hydroxy-tautomers are detected in significant amounts only in 

In this chapter we ntilise the generally accepted terms 2-pyridone , 4-pyridone rather than the strictly correct 2(l//)-pyridinone , etc. 

All three amino-pyridines exist in the amino form the a- and y-isomers are polarised in a sense opposite to that in the pyridones. 

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