the 
 major plant growth regulator ethephon degrades to ethylene 
 and phosphate in aqueous solutions and plants and is spontaneously 
 activated to a butyrylcholinesterase ( bche ) inhibitor in alkaline 
 solutions and animal tissues . in the present 31p nmr kinetic 
 study of the reactions of ethephon in ph 7.4 carbonate buffer , we 
 observed a transient peak at 28.11 ppm . 
 the time course for the appearance 
 and disappearance of this peak matches the activation / degradation 
 kinetic profile of the bche inhibitor , and the chemical shift supports 
 the proposed 2-oxo-2-hydroxy-1,2-oxaphosphetane structure .