# Air- and light-sensitivity of phenol

I've read that phenol should be stored under inert gas and protected from light.

• What reactions does phenol undergo during long-term storage in the presence of air and light?
• Is it really necessary to take such precautions when storing or handling phenol?
• How does the stability of solid phenol compare to that of phenol dissolved in, say, cyclohexane?
• Phenol is oxidized to 1,4-Benzoquinone. Jul 10 '17 at 4:57

Phenol slowly oxidizes on exposure to air and turns pink in color. At first, quinone (p-benzoquinone) is formed which again reacts with phenol to form a polymerized product phenoquinone which is red in color.

There has been research on the oxidation of phenol like wet-air oxidation and catalytic oxidation but those are out of scope.

Oxidation of phenol using light has been studied using UV/$$\ce{H2O2}$$/ozone system. From this paper:

The photolysis with 253.7 nm radiation practically does not degrade phenol. But the combination UV/ozone gave better results than the using only ozone. In the degradation of phenol using ozone there are two main reactions: the direct reaction of ozone with phenol and its products and the reaction of the hydroxyl radical generated. Some intermediate products as benzoquinone, catechol and hydroquinone were detected during the degradation of phenol.

So, yes. Necessary precaution are taken such as phenol are kept at brown bottles.

I think solid phenol is less prone to oxidation due to air/light than liquid/azeotropic phenol because of $$\ce{\pi}$$ stacking, efficient packing of crystals and hydrogen bonding leading to stability.

• "Google search" is not appropriate source attribution. BTW you shouldn't reveal urls containing info about your computer, as google urls tend to do. Jun 28 '20 at 17:32
• @Mithoron I removed the Google image URL as per your suggestion. Apart from your suggestion, can you clarify the downvote (assumed you did the downvote)? Jun 28 '20 at 17:36
• Same reason as the new post where you used this incorrect picture of not-an-adduct Jun 28 '20 at 17:38