Sample pre-lab quiz for the Esterification experiment.

1) Consider the table for the formation of esters of acetic acid using different alcohols. What does it tell you about the relative ease of preparation of esters from different types of alcohols?

 R'OH K
methanol 5.24
n-propanol 4.07
2-propanol 2.35
t-butanol 0.0049
  1. esters from primary alcohols are easier to prepare than esters from tertiary alcohols
  2. esters from primary alcohols are easier to prepare than esters from secondary alcohols
  3. esters from tertiary alcohols are very difficult to prepare
  4. all of the above

2) What is the structure of the product of the following reaction?

compound MW bp density other compound MW bp density other
acetic acid 60   1.05 conc. is 17M n-butyl propionate 130 146 88  
isoamyl acetate 130 142 0.87   octanol 130 194 0.83  
isoamyl alcohol 88 128 0.81   octyl acetate 172 210 0.87  
n-butanol 74 117 0.81   sulfuric acid 98   1.84  conc. is 18M
n-butyl acetate 116 126 0.88   methylene chloride 85 40 1.33  

3) The organic mixture to be distilled will contain ester, alcohol, and methylene chloride. If you have made n-butyl acetate, what will be the order of distillation (first to last)? (refer to the above table)

  1. butanol, n-butyl acetate, methylene chloride
  2. n-butyl acetate, butanol, methylene chloride
  3. methylene chloride, n-butyl acetate, butanol
  4. methylene chloride, butanol, n-butyl acetate

4) Which of the distillates in the previous question will you save?

  1. methylene chloride
  2. butanol
  3. n-butyl acetate

5) Will the distillates of alcohol and ester in question 3 be collected as pure alcohol and ester fractions in this simple distillation?

  1. yes
  2. no

6) A student distilled n-butyl propionate and observed a boiling point of 138 degrees. Why is this?

  1. 138 degrees is the average of the boiling points of n-butanol, n-butyl propionate, and propionic acid
  2. n-butyl propionate decomposes at 139 degrees
  3. the atmospheric pressure in Boulder is lower than the CRC standard pressure
  4. none of the above

7) If you run an IR of your product, what are the main diagnostic bands which you will look for to show that you have product?

  1. C=O and O-H
  2. C=O and C-O
  3. C=O and C-H
  4. C-O and C-H

8) Below is the 1H-NMR spectrum of n-butyl propionate. Assign the protons (A-F) to the peaks in the spectrum.

Answers.