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Today, I came across a question which asked name three reagents can be used for identification of phenol. The answer given was:

  1. Neutral $\ce{FeCl3}$
  2. $\ce{ NaNO2 +HCl}$
  3. $\ce {(NH4)2[Ce(NO3)6]}$.

I understand (1) and (2), but I am doubtful about CAN test (3). As far as I have studied in various books, it is used for testing presence of alcohol, and phenol is not alcohol.

Can phenol be detected with a ceric ammonium nitrate test?

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2 Answers 2

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With unsubstituted phenol ($\ce{PhOH}$) dark-brown precipitation is formed:

$$\ce{(NH4)2[Ce(NO3)6] + 2 PhOH -> [Ce(NO3)4(PhOH)2] + 2 NH4NO3}$$

Other phenols should produce wine-red solution as expected [1, p. 478]. Also, this and other phenol tests are discussed in [2].

  1. Pavia, D. L. A small-scale approach to organic laboratory techniques, 3rd Ed.; Brooks/Cole, Cengage Learning: Belmont, CA, 2011. ISBN 978-1-4390-4932-7.
  2. Atul, S. The Pearson Guide to Objective Chemistry for the AIEEE; Pearson Education India, 2010. ISBN 978-81-317-3381-3.
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    $\begingroup$ Could you please give some examples of the "other phenols"? Would phluoroglucinol work? Or are only monohydroxy derivatives are acceptable? $\endgroup$
    – Gaurang Tandon
    Commented May 7, 2018 at 16:30
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I have mentioned CAN test of alcohol and phenol in a previous answer of mine, so I am going to directly quote that:

Genereally, CAN test is done for alcohols which give pink or red colour. But for phenols and phenolic compounds, it gives brown or black color. So, this test helps to differentiate phenols from alcohols. 

Unfortunately, the source link is broken. :(

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