2667375 EtOx 2-ethyl-2-oxazoline 19 929495 EOz 2-ethyl-2-oxazoline 3 2651970 EOTx 2-ethyl-2-oxazoline 1 929478 EOX 2-ethyl-2-oxazoline 1 1975267 EtOxa 2-ethyl-2-oxazoline 1