CA 3- Lab Exercise 10

Question 1

How was the reaction conducted and then terminated?

Answer 1

Conducted under reflux, and then terminted by carrying out a series of acid-base extractions

Question 2

How was the crude ester product purified?

Answer 2

by carrying out a simple distillation, during which the product’s boiling point was also obtained

Question 3

What was used to help identify the final organic product?

Answer 3

boiling point nad IR spectroscopy analysis

Question 4

What are organolepic qualities?

Answer 4

odors and flavors

Question 5

What organoleptic qualities are characteristic of simple esters?

Answer 5

• pleasant fruity aromas
• fruit smell/taste often due to one or a complex mixture of esters, used as additives in foods and drinks

Question 6

What is the fischer esterification reaction?

Answer 6

• involves refluxing a carboxylic acid with alkyl alcohol in the presence of an acid catalyst
• carboxylic acid + alcohol (w acid catalyst) forms ester and water byproduct

Question 7

What is the reaction mechanism for Fisher esterification?

Answer 7

• nucleophilic addiction of an alcohol to a carboxylic acid
• forms an unstable tetrahedral intermediate
• this intermediate spontaneously undergoes dehydration to form the ester

Question 8

What class of compound do esters belong to?

Answer 8

carboxylic acid derivatives

Question 9

What is a limitation of carboxylic acid derivatives important to this lab?

Answer 9

• the tendency to spontaneously hydrolyze in the presence of water back to the starting carboxylic acid and the nucleophile that forms it

Question 10

What phenomena is referred to as thermodynamic reversibility in the fischer reaction?

Answer 10

the water formed alongside the product in the forward reaction causes hydrolysis of the product in the reverse reaction

Question 11

How can the unfavorable reversibility of the fischer reaction be minimized?

Answer 11

By applying le chatelier’s principle

Question 12

In what ways can Le Chatelier’s principle be utilized to minimize unfavorable reversibility of the Fischer esterification reaction?

Answer 12

• Using an excess of one starting reagent on the left side of the equation to shift the equilibrium of the reaction to the right side- the formation of ester product
• Also can remove the water formed from the reaction mixture as the reaction progresses

Question 13

How can water be removed from the reaction mixture as the reaction progresses?

Answer 13

• using molecular sieves
• installing an apparatus designed to trap and separate water as it is formed in the reaction

Question 14

Procedure overview

Answer 14

1. Complete a one-step synthesis of an acetate ester using unknown alcohol using Fischer esterification method
2. After synthesis, purify and analyze your product’s physical properties (boiling point and refractive index)
3. Calculate percent yield of the final ester product