Applications Illustrating the Methods

This system nicely illustrates many of the principles outlined in the first section. Most of the work was done using Ni[P(OEr)3]4 or Ni[P(OMe)3]4 as catalysts in methanol solvent. In the presence of a strong acid cocatalyst, such as H2SO4 or HCl (but not without cocatalyst), butenes can be isom-erized within minutes at room temperature to an equilibrium mixture of the linear isomers. This is probably the most active olefin isomerization catalyst system known. 

Using 1-butene (the least stable isomer, abbreviated 1-B) as the starting olefin, the rate law (at the beginning of the reaction) is given by Equation 60, 

A plot of /cobs against will give a straight line since 

In an experiment at room temperature using D2SO4 in CH3OD, 39% of the original 1-butene was isomerized in 15 s. There was some rfi-1-butene (0.5%), but more than 99% of the 2-butene products were undeuter-ated. The ratio of isomerization to deuteration is about 170. In spite of this, we are confident that the reaction involves olefin insertion into a nickel hydride to form a nickel alkyl intermediate, followed by de-insertion of 

On long exposure of 1-butene to a similar solution, one obtains a thermodynamic mixture of the isomers (about 6% 1-butene, 25% cis-2-butene, and 69% fran5-2-butene) along with statistical scrambling of the deuterium originally present in solution with all of the hydrogens of the C4H8/  

---