CHE 230 – Organic Chemistry

Exam 3, April 14, 2004

Name ___________________________ Student ID Number ________________

Before you begin this exam: First: You are allowed to have a simple model set at your seat. Please put away all other materials. Second: Place your student identification on your desk. A proctor will come around to check everyone’s ID. Third: Read through the entire exam. Do not waste time on problems that you can’t do if there are others that look easy. Fourth: It is critically important that your answers be written in a clear, unambiguous manner. Answers in which your intentions are unclear will not receive credit. Fifth: Read the instructions for each problem. You will have until 9:50 to complete this exam. There will be no extensions, so budget your time carefully.

Problem Points Score

A. 25 _____

B. 15 _____

C. 10 _____

D. 10 _____

E. 10 _____

F. 16 _____

G. 9 _____

H. 5 _____

Total 100 _______

A. (5x5=25) Complete each of the following reactions with the major organic product.

B. (3x5=15) For each reaction below, write, in the box provided, the reagents needed to change the starting material on the left into the product on the right.

C. (2x5=10) The reagents and products of two reactions are shown below. Draw the structure of the starting material that will lead to the product(s) shown.

D. (10) Draw reactions needed to prepare 2-methyl-1-propanol, B, from 2-methyl-2-propanol, A. There is no single reaction that will do the job. The most efficient strategy is to work backwards from B.

E. (10) Draw a mechanism for the following reaction. Use the curved arrow convention. Clearly show the intermediates and the correct number of steps.

F. In the addition of HBr to 1,3-butadiene the intermediate carbocation, B, is formed. Two products, C and D, are formed from B.

(a) (8) On the energy diagram below locate A, B, C and D by writing those letters in the the appropriate boxes. (There are too many boxes and some should be empty.)

(b) (4) Which is the product of kinetic control? ________

(c) (4) Which is the product of thermodynamic control? ________

G. (5) Draw one more of the five major resonance forms possible for the anion below.

(b) (4) How many signals would appear in the ¹³C NMR spectrum of the resonance stabilized anion above.

_______________

H. (5) Draw the product of the following reaction, showing its stereochemistry.