Question

In today’s experiment, we will react isopentyl alcohol with acetic acid to produce isopentyl acetate. Isopentyl acetate smells like bananas:

CH3 O CH3 O
+
H3COH H3C -H2O H3C O CH3
Isopentyl Acetate
However, instead of using conventional heating, we will use microwave energy to promote the reaction and we will use an acidic resin, Dowex-50, in place of the mineral acid to catalyze the process.
Questions
1. The three standards have different retention times on the Mini-GC. What physical characteristics of the molecules do you think contributes to this?
2. What role does the acid play in the Fisher esterification?
3. What role does the silica gel play in the reaction?

Procedure

• Glacial acetic acid (4.0 mL, 70 mmol, 3-methyl-1 butanol (2.5 mL, 23mmol), Dowex-50 (0.3 and silica gel (0.4 g) are added to a microwave vessel
• A stir bar is added
• The vessel is filled with a vessel top and disk and a torque wrench is used to tighten the top in place
• The vessel is placed in the microwave carousel, making note of the past oon
• The carousel is placed in the microwave and heated using the programmed condition
• After cooling, remove a small sample for gca analysis. Leave the solids behind
• Decant the liquid into a sepratory funnel and dilute with 10 mL of ether
• Carefully wash the ether sequentially with saturated sodium bicarbonate two times and water
• Transfer the ether to a dry Erlenmeyer flask and dry with a sodium sulfate
• Transfer the ether to a pear shaped flask and concentrate on the
• Obtain weight (after evaporation)and calculate percent yield- 51.808 in pear shaped flask . pear shaped flask weight =50.455g - 53.994 (before evaporation)
51.808 after evaporation minus flask = 1.363 final weight.
• Inject sample of your material into the GC and record the retention times.

Answer 1