Question

Fisher Esterification lab.

1. What can happen if the water produced in the reaction is not removed, and the same conditions of reflux and temperature continue?

2. Complete the following table by writing the missing names:

Carboxylic Acid Alcohol Ester 2-Isopropyl Methylpentanoate Isopropanol Methanol salicylic acid

3. Consider the start of the reaction (time 0) when all the reagents necessary to carry out the esterification have been mixed.

a. What signals of the corresponding IR spectrum of that initial reagent mixture should be observed to change significantly when the reaction is complete?

b. What signals of the corresponding 1H NMR spectrum of that initial reagent mixture should be observed to change significantly when the reaction is complete?

4. If you suspect that your product is contaminated with alcohol used in excess in the reaction. What spectroscopic technique would you use to confirm it? Explain

PLEASEEEE, ANSWER ALL THE QUESTIONS AND DO NOT WRITE THE ANSWERS ON A PAPER. THANKS!

Answer 1

Ans of 1 At equilibrium, the forward and reverse reaction rates are equal. If some product is removed from the system, which decreases the rate of the reverse reaction, resulting in the imbalance in rates. So the system will experience a temporary net reaction in the forward direction to re-establish equilibrium (the equilibrium will shift right according to Le Châtelier's Principle). If the water produced in the reaction is not removed, and the same conditions of reflux and temperature continue, then the reaction equilibrium will not shift further towards the product side, i.e. it will decrease the product yield than in the case when water is removed. Ans of 2 Alcohol Isopropanol Carboxylic Acid 2-Methylpentanoic Acid Salicylic Acid Ester 2-Isopropyl methylpentanoate Methylsalicylate Methanol Ans of 3a The broad and strong O-H stretching which appears generally around 3300-3500 cm' for alcohol and broad and weak O-H stretching around 2500-3000 cm for acid will disappear when the esterification reaction is complete. Ans of 3b The sharp singlet proton peak for carboxylic acid part (COO-H) around 12-14 ppm region will get disappeared when the esterification reaction is complete. Ans of 4 If the product is contaminated with alcohol used in excess in the reaction; IR spectroscopic technique should be used to confirm it. As broad and strong O-H stretching will appear in the region 3300-3500 cm for alcohol, if some alcohol is left in the reaction mixture.