Explanatory notes
… 29.30 and 29.31 are organic compounds whose molecules contain, in addition to atoms of hydrogen, oxygen or … ring(s), in addition to the carbon atoms, atoms of other elements such as oxygen, nitrogen or sulphur. In this way, … groups are derived : (A) FIVE-MEMBERED RINGS (1) Containing one hetero-atom : (a) Of oxygen : Furan group …