Sublimation of Phthalic Anhydride

Chemicals needed

Phthalic anhydride GSGESUND.gif (476 Byte) Xn   R 22-37/38-41-42/43    S (2)-23-24/25-26-37/39-46

One can also use other easily vaporized substances, such as iodine or caffeine, but phthalic anhydride forms splendid crystal fibers and no harmful vapors are emitted from the apparatus.

Equipment needed

stand with two sleeves and clamps
two test tubes (one big, one small, must fit inside one another)
burner (preferably alcohol-)

Test procedure



Many solid substances are volatile enough such that they can be vaporized (sublimation), with cooling one can then precipitate them again (resublimation). One actually speaks of sublimation only in that case where a substance passes without melting into a gaseous state (e.g. iodine). Sublimation is a useful process in the laboratory in order to purify small amounts of sufficiently volatile and thermally stable substances.Industrially with this process large amounts of substances are purified, e.g. iodine or sulphur.


DSCN0066.JPG (235762 Byte)

Experimental apparatus before heating

DSCN0072.JPG (211696 Byte)

Experiment shortly before ending heating, the resublimated anhydride is clearly seen within the cooling finger.


derived from V315 "Phtalsäureanhydrid", S. 184, [1]