Basic Organic Chemistry Techniques

Laboratory procedures in organic chemistry typically utilize standard glassware equipment and techniques. Beakers and Erlenmeyer flasks are often used for simple mixing and holding solvents. Round-bottom flasks with either a short or a long neck are used for reactions under high heat or vacuum. This is because the round shape is more resistant to cracking under these conditions.

Heating reactions is a common lab procedure. However, a Bunsen burner is not generally used for organic compounds because they are flammable. When heating a reaction in a beaker or Erlenmeyer flask, a hot plate with a magnetic stirrer is typically used. When heating a reaction in a round-bottom flask, a water bath or heating mantle is used to accommodate the shape of the flask.

Many reactions must be heated to a certain temperature for a specific amount of time to proceed. These reactions are performed under reflux. A reflux setup uses a round-bottom flask containing a solvent whose boiling point overlaps with the optimal temperature of the reaction. A condenser is fitted onto the flask, and cold water enters at the bottom arm and exits out the top arm. As the mixture is heated and stirred, the solvent evaporates and then condenses back into the flask, preserving the reaction volume.

Another common technique used in the organic chemistry lab is filtration, which is a method to separate solids from liquids. Gravity filtration is the simplest filtration technique used to separate granular insoluble solids. This setup consists of an Erlenmeyer flask, a conical funnel, and a folded piece of filter paper. The mixture is poured into the funnel, and the liquid passes through into the flask, called the filtrate. The solids remain on the filter paper.

A faster filtration technique is vacuum filtration. Here, a Büchner funnel is connected to a filter flask using a rubber adaptor. The filter flask looks like an Erlenmeyer flask, but it has a side arm that connects the flask to the vacuum via vacuum tubing. Then, a flat piece of filter paper is placed inside of the funnel and wet slightly before the vacuum is slowly turned on. The liquid is sucked through the filter paper into the flask, while the solid is retained on the filter paper.

In this lab, you will perform a simple reaction to form benzoic acid, enabling you to practice simple organic chemistry techniques, like weighing solids, measuring volume, and performing vacuum filtration. You'll then practice the reflex technique using tetrahydrofuran.