Kinetics of the uncatalyzed hydrostannation of diethyl acetylenedicarboxylate

Hydrostannation of carbon-carbon triple bonds is usually catalyzed by a free radical initiator or by metal complexes of palladium, molybdenum or rhodium. However, when the triple bond is substituted with an effective electron-withdrawing group, the addition reaction will proceed in the absence of a catalyst. In this paper we report the kinetics of hydrostannation of diethyl acetylenedicarboxylate, (1), with trimethylstannane (2a), tri-n-propylstannane (2b), tri-n-butylstannane (2c), and triphenylstannane, (2d). Rate constants for these reactants were determined in acetonitrile at 25, 35, and 45 degreesC. Also, rate constants for trimethylstannane and tripropylstannane were determined in cyclohexane and trimethylstannane-d(1) (2e), in acetonitrile. Finally, the hydrostannation with tributylstannane was run at 25, 35, and 45 degreesC in 95% ethanol. Where appropriate, enthalpies and entropies of activation were determined.