Saturated heterocycles. 70 . Application of the seth‐paul‐van duyse equation. 10 . The C  O stretching frequencies and transmission of substituent effects in 5,6‐polymethylene‐2,3,5,6‐tetrahydro‐1,3‐oxazin‐4‐one derivatives

The C O stretching frequencies of twenty‐six cis ‐5,6‐polymethylene‐2,3,5,6‐tetrahydro‐1,3‐oxazinone derivatives were measured in tetrachloromethane and in chloroform and correlated with the substituent constants X+(R) in the sense of the modified and extended Seth‐Paul Van Duyse equation. The influence of the fused hydrocarbon ring on the C O stretching frequency and on the transmission of substituent effects through the six‐membered heterocyclic ring is discussed and compared with that in the previously investigated 5,6‐polymethylenepyrimidin‐4(3 H )‐ones and cis ‐5,6‐dihydropyrimidin‐4(3 H )‐ones.