A two part organic laboratory experiment illustrating the Grignard reaction and the concept of kinetic versus thermodynamic control is described. The reaction of phenylmagnesium bromide with 2-methylcyclopentanone yileds an unsymmetrical benzylic alcohol which can be dehydrated using toluenesulfonic acid to give predominately the less substituted alkene. Application of heat to the reaction mixture over a period of two hours reverses the trend to give the more substituted alkene as the major product in 91% relative yield. The dehydration is monitored by GC/MS and the experiment can be performed using macro and microscale techniques.
Department, Program, or Center
School of Chemistry and Materials Science (COS)
Journal of Chemical Education 74N10 (1997) 1218-1220
RIT – Main Campus