Chemistry Department

 

University of Alberta

           

CHEM 263 B2

 

Exam I

 

Thursday, February 12, 2009

 

1.    The IR and ¹H NMR spectra of a compound of molecular formula C₅H₁₀O₂ are given below. 

 

SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/ (15-01-09)

 

Here is the spectrum amplified between 0 and 4 ppm:

 

a.    Calculate the degree of unsaturation. (1 point)

 

(2 x 5 – 10 + 2)/2 = 1

 

b.    List the possible functional groups gleaned from the molecular formula. (3 points)

 

carboxylic acid

ester

alcohol

aldehyde

ether

ketone

 

c.    What is the oxygen-containing functional group that the IR spectrum shows to be present in the unknown? (1 point)

 

carboxylic acid

 

d.    Propose a structure for this compound. (10 points)

 

           

 

 

2.    Sketch the expected ¹H NMR spectrum of the following compound:

 

 

           

 

 

3.    Benzoquinone is a very reactive dienophile.  It reacts with 2-chloro-1,3-butadiene to give a single product, C₁₀H₉ClO₂, in 95% yield.  Draw the structure of this product.

 

 

 

 

4.    When either 1-chloro-3-methyl-2-butene or 3-chloro-3-methyl-1-butene is treated with moist Ag₂O, in addition to the formation of AgCl, mixture of alcohols is obtained:

 

 

a.    Propose a mechanism to account for the formation of the two products.

 

b.    Explain the relative yields of the two products.

 

 

The following cation is the more stable :

 

 

 

5.    Explain the observed rate of reactivity of the following chlorides in an S_N1 reaction:

 

 

Look at the intermediate carbocations:

 

 

 

 

6.    Provide a synthetic pathway for the following transformation:

 

 

 

7.    Give the structure(s) of the principle organic products of the following reactions:

 

a.     

 

b.     

 

c.