11 mmol or 1.58 grams of isopentyl propionate was expected to be recovered from the acid-catalyzed reaction of 11 mmol of 3-methyl-1-butanol with 13 mmol of propionic acid. However, only 0.292 g of final ester product resulted in a low recovery rate: 18.5%. Low percent recovery could have been due to reflux reaction not going to completion (substantial amounts of unreacted alcohol and carboxylic acid remained in the rb flask after reflux) or loss of organic product during reaction work-up.
Isopentyl propionate had a sugary banana odor, compared to 3-methyl-1-butanol’s bittersweet licorice smell and propionic acid’s bitter vinegar smell. The odor test confirms formation of isopentyl propionate as it is known for its usage as a flavor extract: mainly fruity, ripe, banana smell.
The IR spectroscopy of isopentyl propionate also confirms the formation of an ester product, since it displays the characteristic carbonyl peak specific to esters: sharp, strong, 1740/cm. However, there is some unreacted alcohol product left in the final sample, as evidenced by the broad peak of medium intensity at 3300/cm.