My teacher told me we can convert benzene to phenol within a single step using $\ce{V2O5}$/ $\ce{O2}$ at 300 ⁰C (not 500 ⁰C). Later I searched for that reaction but I couldn't find it in all over Google except in Allen's Chemistry handbook.

Does that reaction really occur and if it occurs then what is the mechanism of that reaction?

enter image description here

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    $\begingroup$ I don’t think that we can get phenol from benzene just by $\ce{V_2O_5}$. As you know, $\ce{V_2O_5}$ is an oxidising agent, it will oxidise our benzene. $\endgroup$ Commented May 21, 2020 at 4:45
  • $\begingroup$ Related(for the maleic anhydride case): chemistry.stackexchange.com/questions/8209/… $\endgroup$ Commented May 21, 2020 at 8:05
  • $\begingroup$ Also related: pubs.acs.org/doi/abs/10.1021/i200015a003 $\endgroup$ Commented May 21, 2020 at 8:09
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    $\begingroup$ TL; DR: Not exactly ratta maar, a mechanisms is there.. Perhaps it maybe beyond your current level of understanding,or tour teacher is unaware of the same $\endgroup$ Commented May 21, 2020 at 8:12

2 Answers 2


The reaction of benzene over $\ce{V2O5/ PtAu}$ catalyst at lower temperatures, can convert benzene to phenol with some success.

See this book here Direct hydroxylation of benzene

[The original question before editing was: What is the Ratta Maar Reaction?] Someone has played a prank with you with the named reaction. "Ratta maar" is a slang for "rote memorization" in Hindi/Urdu, which implies keep on memorizing without understanding and perhaps this is what your teacher wanted too. I assume this Allen's Chemistry Handbook is being taught or used in India.

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    $\begingroup$ Allen is a coaching institute for the JEE exams... You'll find many such "unexplained" phenomena in the coaching manuals. Half of the traffic on SE is due to these questions caused by loose ends which were not explained fully, because they won't ask the reason in the exam. $\endgroup$
    – Micelle
    Commented May 21, 2020 at 8:30
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    $\begingroup$ @Micelle Yeah,I know about Allen and such related cram schools(once prepared for such exams myself). And sadly,your point is very true; this reaction does have a mechanism as I have higlighted in the comments above,but if the teacher doesn't know it or isn't willing to teach it,he proclaims it as ratta maar. This creates a false impression about the nature of chemistry in high school students, and hence there questions are highly downvoted on SE. It's painful to watch as there questions receive negative ratings and are closed ultimately :( $\endgroup$ Commented May 21, 2020 at 8:44
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    $\begingroup$ @YusufHasan, If you are interested in why chemistry never attracts the best and the brightest, you should read "Chemistry: Fact or Fiction" by Gillespie from 1970s-yes the same person who came up with VSEPR theory. Despite being a 50 year article, the facts remain true today. $\endgroup$
    – ACR
    Commented May 21, 2020 at 10:14
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    $\begingroup$ @zombie You didn't get my point. I haven't used any slang; he did as he gave the reaction a made-up name RMR. Moreover,it is the duty of the teacher to teach the mechanism of the reaction along with the reaction equation(if a mechanism exists). If he doesn't do so, atleast he or she should state outright that a mechanistic pathway exists for this reaction,but we won't be covering it here. Stating a reaction outright as "Ratta Maar" (meaning rote memorization) when studies on mechanisms have been done is both incorrect as well as undermining to the scientists who have worked on the research.... $\endgroup$ Commented May 21, 2020 at 10:17
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    $\begingroup$ I agree with @M.Farooq, IIT JEE is a kind of smudge in the education system that needs to be stained off. No exam will ever want a student to memorise 50-100 without even knowing “where can we find vanadium for making $\ce{V_2O_5}$?”. $\endgroup$ Commented May 21, 2020 at 10:27

The terminology given to that reaction by your instructors is very odd. But the more important thing is that $\ce{V_2O_5}$ isn't a reagent in converting benzene directly to phenol, rather it is a catalyst. The first few pages of the book linked by @M.Farooq writes

[...] Various sources have reported the use of nitrous oxide to supply the active oxygen [1-8]. Iwamoto et al. appear to be the pioneers in the early 1980s, where they employed $\ce{N_2O}$ over a $\ce{V_2O_5 - SiO_2}$ catalyst and reported a benzene conversion of $11\%$ and a phenol selectivity of $45\%$.

And even in this article it is written about vanadium oxides that

These materials have been tested in the hydroxylation of benzene to phenol in liquid-phase with molecular oxygen in the absence of reductant. The catalyst exhibits high selectivity for phenol (61%) at benzene conversion of 4.6%, which is a relatively good result in comparison with other studies employing molecular oxygen as the oxidant.

So, you notice the oxygen for phenol comes from either from $\ce{N_2O}$ or molecular oxygen itself, while $\ce{V_2O_5}$ is just a catalyst. But in your original post you have written

My teacher told me we can convert benzene to phenol within a single step via Ratta Maar Reaction using $\ce{V_2O_5}$.

There is no mention of nitrous oxide or molecular oxygen (although in images you do have molecular oxygen). So, the gist is that your instructors told you something but didn't care to explain the intricacies and complexity of conversion.


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