Chemistry Workshops
1. Write a detailed stepwise mechanism for the transformation shown below. Identify each species in the mechanism as a Lewis acid or Lewis base and use curved arrows to show the movement of electron pairs. Construct a plot that describes the energy of the system as a function of the progress of the reaction (reaction energy diagram). On your diagram, clearly label the positions of the reactants, any intermediate(s), and the product. Also, specify the energy difference that corresponds to the delta G° for the overall reaction and the energy difference that corresponds to delta G* for each step. Explain (in words) what is happening as the system makes its way from reactants to products.
CH3CH=CHCH3 + HCl -----> CH3CHClCH2CH3
2. Give a reasonable mechanism (use curved arrows to show movement of electron pairs) for the acid-catalyzed polymerization of 2-methylpropene shown below. You need to show just a few of the polymer chain lengthening steps.
3. The addition of HI to 2-methylpropene can, in principle, give either 1-iodo-2-methylpropane or 2-iodo-2-methylpropane. In practice, only the latter is formed. Show mechanisms for the formation of each of these alkyl iodides, using curved arrows to indicate the movement of electron pairs. Also, construct reaction energy diagrams that describe the energy of the system as a function of the progress of the formation of each alkyl bromide. Use these reaction coordinate diagrams to explain why 2-iodo-2-methylpropane is the only product.
4. Create a chart that shows the stereochemical possibilities that can arise from the addition of a general compound X2 to 2-butene. Consider either cis- or trans-2-butene as the starting material, and consider either syn or anti addition.
Materials adapted from:
Peer-Led Team Learning: Organic Chemistry, 1/e
Jack A. Kampmeier, University of Rochester
Pratibha Varma-Nelson, St. Xavier University
Donald Wedegaertner, University of the Pacific
Prentice-Hall, 2001, ISBN 0-13-028413-0
http://www.sci.ccny.cuny.edu/~chemwksp/OrganicChem.html
