Techniques Used in the Esterification Reaction.

For good results, exact measurement of reagents is essential. Alcohol and carboxylic acid will be measured with a calibrated pipet, using a pipet pump to draw liquid into the pipet. Hold the pipet/pipet pump assembly with two hands, so that the thumb of one hand can be used to move the thumbwheel.

Place the pipet into the liquid and draw liquid up into the pipet by turning the thumbwheel until the liquid is at the 0 mL mark as shown (note that in this example a red dye has been used for clarity).

Liquid will tend to drip out the end of the pipet. To help prevent this, after the liquid is at the 0 mL mark, draw a little air into the pipet and tilt it slightly. Without hesitation, place the pipet tip into the round-bottomed (rb) flask, which is standing in a small beaker and, holding the pipet upright, deliver the correct amount of liquid by moving the thumbwheel until the desired reading is reached on the pipet. In this example, the amount that was delivered is 0.77 mL.

Heating the reaction mixture. A side-on view of the heating set-up is shown below. Note that the heating rate must be such that vapor condenses above the side-arm but no higher than about 1/2 way up the condenser tube.

Final Distillation of the Ester. A simple distillation using a slightly different set-up than used in previous distillations is used to purify the ester product. The set-up is shown below. Note that the low placement of the thermometer is necessary for an accurate boiling point reading. The sand bath is raised slightly above the benchtop using an iron ring. This allows the collection vial to fit under the condenser exit.