Organic Chemistry Laboratory Techniques, 2016a

1.1.E CLEANING GLASSWARE
Glassware should be dismantled and cleaned as soon as possible. Experience with home dishwashing can
tell you that dishes are more difficult to clean when allowed to dry. If there is a time constraint, it’s best to
leave glassware in a tub of soapy water.
To clean glassware, use the following procedures:
•
Use 2-3 mL solvent to rinse residual organic compounds from the glassware into a waste beaker. The
compounds should be highly soluble in the solvent. The default solvent is often acetone as it is
inexpensive, relatively nontoxic, and dissolves most organic compounds. Some institutions reuse their
acetone (“wash acetone”) as the solvation ability is not spent after a few uses.
As it will soon become second-nature for most students to use acetone as part of their cleaning ritual,
it is worth reminding that the purpose of an acetone rinse is to dissolve organic residue in a flask. Not
everything dissolves in acetone, for example ionic salts are insoluble in acetone and are more
successfully rinsed out with water.
•
After a preliminary rinse, glassware should then be washed with soap and water
at the bench.
Residual acetone will likely evaporate from the flask, but it is acceptable for small
quantities of residual acetone to be washed down the drain. Acetone is a normal
biological byproduct of some metabolic processes, 1 and has low toxicity as it can
be easily excreted by most organisms.
If using undiluted detergent from the store, it is best to use small amounts during
washing as they tend to form thick foams that need lots of rinsing (Figure 1.10).
Some institutions instead use dilute soap solutions at their cleaning stations for
this reason. For cleaning of glassware, the biodegradable detergent “Alconox” is
the industry standard.
Figure 1.10: Detergent
foaming during washing.
•
Rinse all glassware with a few mL of distilled water, then store wet glassware in a locker atop paper
towels to evaporate by the next lab period.
1.1.F DRYING GLASSWARE
1.1.F.1 QUICK DRYING
If dry glassware is not needed right away, it should be rinsed with distilled water and allowed to dry
overnight (in a locker). If dry glassware is promptly needed, glassware can be rinsed with acetone and the
residual acetone allowed to evaporate. Rinsing with acetone works well because water is miscible with
acetone, so much of the water is removed in the rinse waste. Evaporation of small amounts of residual
acetone can be expedited by placing the rinsed glassware in a warm oven for a short amount of time or by
using suction from a tube connected to the water aspirator. Residual acetone should not be evaporated
1 R. Boyer, Concepts in Biochemistry, 2 nd edition, 2002, Brooks-Cole, p 565.
Organic Chemistry Laboratory Techniques | Nichols | Page 24