Aridity kinetic control

Ketyls, 218 Kinetic aridity, 280 Kinetic control, 42, 151 addition to 0=0, 235 addition to dienes, 195 Diels-Alder, 350... 

Both primary and secondary amines add to (r,/3-unsaliirated aldehydes arid ketones to yield /3-amino aldehydes and ketones rather than the alternative imines. Under typical reactioit conditions, both modes of addition occur rapidly. But because the reactions are reversible, they gejieral y proceed with thermodynamic control rather than kinetic control (Section 14.3), so the more stable conjugate addition product is often obtained to the complete exclusion of the less stable direct addition product. 

A cyclic enzyme system, where two enzymes share a substrate in a cyclic manner, was assumed to be the control element of a feedback system to maintain the stationary concentration of the end product at a desired level against external perturbation (Okamoto Hayashi, 1984). Switching behaviour is shown by a mass action kinetic model involving interactions among the active E and inactive ( j) form of the cyclic enzyme, the inhibitor (Tj), the activator ( 2) arid the end product ( 3). The model is ... 

---