Experiment 10: Preparation of Banana Oil 2

© Professors Kathleen V. Kilway and Andrea Drew, Department of Chemistry, University of Missouri – Kansas City, 2007 – CHEM 322L

10.

Fisher Esterification: Preparation of Banana Oil
Reactions of Esters: Addition - Elimination, Chapter 19.7, pgs 1049-1058 Fischer Esterification, Figures 19.32 and 19.33, pgs 1049-1050

M. Jones:

This procedure has been adapted from the microscale procedure described in the third edition of Macroscale and Microscale Organic Experiments by Kenneth L. Williamson (Houghton Mifflin, Boston, 1999).

Background
Esters. Esters have the structure of -COOR. Instead of the alcohol portion of the carboxylic acid (-COOH), there is an ether portion. The low boiling, volatile esters are known for their "fruity" smell and flavor. They are used in artificial flavorings. Some typical esters, which are used as artificial flavors are listed in the table below (Operational Organic Chemistry, John W. Lehman, Third Edition, Prentice Hall, 1999). The "taste" of a candy or food is a special science, food chemistry. It is an art to create are combinations of different flavorings that imitate a "natural" flavor. Table 1. Name 1- propyl acetate octyl acetate isopentyl acetate isopentyl acetate isobutyl propionate ethyl butyrate

Structure CH3CO2CH2CH2CH3 CH3CO2(CH2)7CH3 CH3CO2CH2CH=C(CH3)2 CH3CO2CH2CH2CH(CH3)2 CH3CH2CO2CH2CH(CH3)2 CH3CH2CH2CO2CH2CH3

Flavor pear oranges "Juicy-Fruit" banana rum pineapples

CHEM 322L

Experiment 10: Preparation of Banana Oil 1

In this experiment, you will be performing a Fischer esterification. The general mechanism is pictured in Figure 1. O R O H ROH2 ROH R O R O

Figure 1. The overall reaction for Fischer esterification. The overall mechanism for a general acid and alcohol is depicted in Figure 2. H H O R O H OR O P ROH2 ROH R ROH O H ROH H H A R OR OH OH D H H OR R OR OH OH

OH2 P L R OR OH R

O

H

ROH D R

O + ROH2 OR

OR

Figure 2. The general mechanism for Fischer...