1. (16 pts) Provide an acceptable name for each of the following molecules, being sure to address stereochemistry where appropriate. It is not necessary to assign E/Z designations to cycloalkenes.
 

 

2. (12 pts) For each of the following four molecules, list the properties from the list on the right which best describe it. Each item on the list can be used as often as necessary, or not at all. You are penalized for both missing and incorrect answers, so DON'T GUESS!!
 

a. forms the least stable carbocation upon loss of bromide ion b. SN1 reaction very facile c. contains no sp3 carbon atoms d. capable of E1 reaction to form an alkene e. whether SN1 or SN2 mechanism is solvent-controlled f. incapable of an elimination reaction g. completely planar (all atoms) h. SN2 reaction is essentially impossible i. SN2 reaction is very facile j. reacts with bromine (uncatalyzed) k. capable of E2 reaction to form an alkene

3. (12 pts) Draw all of the carbocations formed by the addition of H⁺ to each of the following alkenes, and indicate (by circling the appropriate word) which is the more stable (major) , less stable (minor), or if each carbocation is of equivalent (equiv.) stability.
 

 

A = starting materials B = products C = reactive intermediate D = enthalpy E = rate-determining Eact F = other Eact G = TS#1

What is the difference between a transition state and a reactive intermediate?

A transition state is characterized by partially formed or partially broken bonds, and thus is very high energy.  A reactive intermediate, conversely, possesses only fully-formed or -broken bonds, and thus is not of as high energy as a transition state.

5. (20 pts) Complete the following reactions. If more than one product is formed, draw only the major one.
 

 

---

6. (10 pts) Outline the mechanism of the reaction (diagrammed in the box) of 1-bromo-1-methylcyclopentane and ethanol to form the ether 1-ethoxy-1-methylcyclopentane, with the alkene 1-methylcyclopentene as a by-product. Your mechanism must account for both products.

 

---

7. (12 pts) For each terpene below, indicate the isoprene units by drawing a wavy line through the bonds separating each unit (as was discussed and demonstrated in class). Be certain that your wavy lines are extremely clear, and go through bonds and not atoms. If it is not clear, it cannot be accurately graded; you will not get the benefit of the doubt by partially-erased lines, lines which are drawn through atoms, etc.

Bonus (5 pts, no partial credit possible) The transformation in the box is a useful ring-forming reaction, whose mechanism is strictly analogous to the acid-catalyzed addition of water to an alkene with which you are familiar. Draw this mechanism below.