2-Aryl-2-methoxy-5, 5-dimethyl-Δ3-1, 3, 4-oxadiazolines (4) and 5-aryl-2-methoxy-2, 5- dimethyl-Δ3-1, 3, 4-oxadiazolines (5) were synthesized. Compounds 4 decompose in solution with first order kinetics. Rate constants are correlated with Hammett substituent constants (σ-) with ρ (49.2° C)= 0.74 and 0.89 for CCl4, and CD3OD, respectively. The final products from 4 indicate that thermolysis involves the cleavage of both CN bonds, to form ...