The partial oxidation of propan-1-ol

This is the first organic preparation in the course and you will probably be meeting Quickfit apparatus for the first time. We use sodium dichromate(VI) acidified with sulfuric acid as the oxidizing agent in this experiment. Sodium dichromate (VI) is chosen in preference to potassium dichromate (VI) because it is more soluble in water. We need to ensure only partial oxidation takes place in order to produce the aldehyde, propanal. This is done by using a calculated, limited amount of oxidizing agent:

Na₂Cr₂O₇ + 3C₃H₇OH + 4H₂SO₄ ⇒ Na₂SO₄ + Cr₂(SO₄)₃ + 3C₂H₅CHO + 7H₂O

We also distil out the aldehyde as it is formed so that it is not in the presence of the oxidizing agent for sufficient time to cause further oxidation. We shall check our product with some simple chemical tests.

Video - the oxidation of propan-1-ol to propanal

You should have noted a brick red precipitate with the Benedict's solution indicating the presence of the aldehyde. However, no reaction occurred with the sodium carbonate solution showing the absence of any carboxylic acid.