jarynth
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Synthesis of phenol
Does anyone have experience with the Dakin reaction to gain phenol from benzaldehyde, acetophenone, etc (R=H; R'=H, CH3, ...)?
http://www.organic-chemistry.org/namedreactions/Dakin.1.gif
In particular, could we start with salicylamide (R=ortho-OH; R'=NH2) to get catechol?
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Nicodem
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The Dakin reaction works on benzaldehydes and only exceptionally on ketones. It does not work on benzamides. Besides, even on benzaldehydes it is only
works particularly well on o- and p-hydroxybenzaldehydes, while on other benzaldehydes it either work less efficiently or requires modifications. For
the more troublesome benzaldehydes and acetophenones the Baeyer-Villiger oxidation is more efficient and the phenyl esters that form are easily
hydrolysed to phenols (sometimes already at the reaction conditions). But not even the Baeyer-Villiger oxidation works on benzamides.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
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Klute
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You could form benzonitriles from the amides, and thenr educe with copper-treated Raney nickel to obtain the aldehdye. I think certain CTH with HCOOH
can do this also, there was a discussion on this not too long ago. But that would be a veerrry loong way to phenol. At that point you could even start
considering starting from cumene!
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Nicodem
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That would be one hell of a synthesis of something as cheap and easily available as catechol. The cost of all the reagents and solvents used would
amount to many times the price of the product. 
Anyhow, Klute could you please post the reference to that "copper-treated Raney nickel to obtain the aldehdye". Sounds like an interesting alternative
to SnCl2/HCl of which I never heard.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Klute
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See US4500721 for the copper-treated Raney nickel reduction with atm H2, and US4383949 for an example of a CTH with formivc acid and Raney nickel (they also detail the formation of the amide, the nitrile, and acetals of
the aldehyde.
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jarynth
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| Quote: | Originally posted by Nicodem
The Dakin reaction works on benzaldehydes and only exceptionally on ketones. It does not work on benzamides. Besides, even on benzaldehydes it is only
works particularly well on o- and p-hydroxybenzaldehydes, while on other benzaldehydes it either work less efficiently or requires modifications. For
the more troublesome benzaldehydes and acetophenones the Baeyer-Villiger oxidation is more efficient and the phenyl esters that form are easily
hydrolysed to phenols (sometimes already at the reaction conditions). But not even the Baeyer-Villiger oxidation works on benzamides.
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Sadly enlightening. The way the general reaction was written, it looked like there was some choice for R'.
Anyway, I also looked at the following alternative routes to phenol, but am not sure about the practicalities. What do you think?
1) Decarboxylation of salicylic acid by refluxing in conc. NaOH (or solid-phase MW method).
2) (WRONG: Diazotization of nitrophenol and reduction.) RIGHT: Reduction of nitrophenol
followed by diazotation 
Both salicylic acid and ?-nitrophenol can be gained from acetylsalicylic acid, or extracted from flants. By the diazotization route we can also make
benzenediols (even easier).
Toxic fine chemicals like phenol are getting increasingly harder to obtain in Europe. Every OTC recipe must be cherished.
[Edited on 3-10-2008 by jarynth]
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Sauron
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How does one diazotize nitrophenol? I think you mean reduction of o-nitrophenol, followed by diazotization in which case maybe you can get some
1,2-benzenediol.
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Magpie
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Did I miss something here, I thought you just wanted phenol?
benzoic acid --> benzene -->nitrobenzene --> aniline ---> phenol
So, any of those intermediates will get you to phenol. Yields may be low if you have to start with benzoic acid or benzene, but you will get some
phenol.
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jarynth
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| Quote: | Originally posted by Sauron
How does one diazotize nitrophenol? I think you mean reduction of o-nitrophenol, followed by diazotization in which case maybe you can get some
1,2-benzenediol. |
You're obviously right, the nitrocompound is the result of the
introduction of a nitro group (eg via chlorophenol and nitrite), nothing to do with diazotization (which also uses nitrite...that's what got me
confused).
| Quote: | Originally posted by Magpie
Did I miss something here, I thought you just wanted phenol? |
I'm talking about different things at once, namely phenol and benzenediols. Sorry about the misunderstanding!
Here's a third route via an isomer of salicylic acid:
3) Anethole -(oxidation)-> 4-methoxybenzoic acid -(decarboxylation)-> anisole -(hydrolysis)-> phenol
[Edited on 3-10-2008 by jarynth]
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chloric1
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Acetylsalicylic acid is easily hydrolysized with dilute H2SO4. Salicylic acid can simple be decarboxylated by strong heating. Some sublimation
occurs but most is converted to phenol. I am interested to learn more about the NaOH route. I imagine you get sodium phenate and sodium carbonate
which can be separated by 95% alcohol.
Fellow molecular manipulator
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Sauron
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He wants catechol, not phenol. Probably, substituted catechols. Of course the thread author keeps bouncing all over the map and is not being very
coherent or comprehensible so thinking he wants simply phenol is not such an error.
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Ephoton
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true sauron but the title is for phenol which is still very usefull.
I do like the aspirin route though I have yet to see any documentation of it working.
why waist an aldehyde if aspirin works.
[Edited on 4-10-2008 by Ephoton]
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Sauron
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Catechols are phenols, just as resorcinols and so on are phenols, phenol itself is not the target, so useful or not, preparation of phenol itself is
off topic, as it is not what the thread author is asking about.
Making phenol is trivial. There are threads on making benzene from sodium benzoate, threads on making chlorobenzene, and once you have chlorobenzene
and sodium hydroxide, you are home free. See Vogel.
All you guys exploiting aspirin must own shares in Bayer.
What does it matter than the guy mistitled the thread? Should have said catechols not phenol. All you have to do is read the first post to see clearly
that catechol or substituted catechols are what he is after. So don't derail the thread.
[Edited on 4-10-2008 by Sauron]
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ScienceSquirrel
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In Europe catechol is available from specialised photography supply houses for use in developer solutions.
If you appear to be a responsible individual with a legitimate reason to own the material then there is no difficulty in buying a hundred grams or so.
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Sauron
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Since in my distant and misspent youth I operated a B&W darkroom for a year or two, this does not amaze me. I have also seen mail order specialty
photographic chemical suppliers advertising in USA. I did not look for catechol on their list, but it ought to be there. Kodak (after all owned by
Eastman Chemical) probably sells it at theirregional offices or can at least order it in.
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jarynth
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| Quote: | Originally posted by Sauron
Catechols are phenols, just as resorcinols and so on are phenols, phenol itself is not the target, so useful or not, preparation of phenol itself is
off topic, as it is not what the thread author is asking about.
Making phenol is trivial. There are threads on making benzene from sodium benzoate, threads on making chlorobenzene, and once you have chlorobenzene
and sodium hydroxide, you are home free. See Vogel.
All you guys exploiting aspirin must own shares in Bayer.
What does it matter than the guy mistitled the thread? Should have said catechols not phenol. All you have to do is read the first post to see clearly
that catechol or substituted catechols are what he is after. So don't derail the thread.
[Edited on 4-10-2008 by Sauron] |
I appreciate your contribution, but I'm interested in both. It might look like I mistitled the thread, but I started it with phenol in mind. The
discussion then involuntarily broadened to include benzediols because of the sneaky -R in the Dakin rxn picture I found.
Of course the (mono-, di-, ...) chlorobenzene route to phenols is straightforward, but I wanted to explore friendlier processes that did not
necessarily go through benzene and chlorine. Aspirin and anethol seem somewhat more benign to the public eye.
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Ephoton
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aspirin is cheap 
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Sauron
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I'm a little fuzzy about what you want and even more so about what you regard as "good" reagents and "bad" reagents.
Also what does public perception have to do with the price of beans?
Benzene might vell be regarded as nasty in EU but benzoic acid, sodium benzoate, and benzyl alcohol, not so. So you can get to benzene and
chlorobenzene from there (the latter via TCCA which the public regards as wimming pool chlorinator). I fail to see how you plan to get to phenols
other than through benzene, chlorobenzene, or aniline?
You can get to various catechols via essential oils like eugenol, for example. The public regards that as a toothache remedy (oil of cloves). Some of
our members can tell you all about how to manipulate that molecule.
I wish you would state your problem more precisely.
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jarynth
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I'm not really stuck with a problem, since I barely used the phenol I bought long ago, and I could probably get some overpriced benzenediols
legitimately as well. Rather, I started some brainstorming for ways to make these simple but interesting compounds. It's exciting to end up with an
unusual compound just by carefree stirring and baking a mixture of red devil and aspirin, or some essential oil. Chlorine, after all, is a reagent
used in many a dull brute force procedure. As to benzene, it's not like that only in the EU, and not even everywhere in the EU In face, I just
recently came across a French site offering that, and even CCl4, as entomology killers...
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Sauron
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No one is particularly suggesting "dull brute force" chlorination of benzene. Axt has a thread on chlorobenzene via TCCA. Does that sound like dull
brute force to you? Once you have chlorobenzene then your choice of lye for alkili fusion will get you phenol. See Vogel.
Do you really think catechol is overpriced? Or resorcinol? Or quinol/hydroquinone? I bet these are cheaper than the essential oils in question. Or the
herbs they come from. I used to buy bulk herbs from Ricard & Frappa in Marseilles so why not ask them for a quote for cloves?
Really unless you narrow your question to a specific target, no one can help you. And having a vaguely defined horror of many reagents is simply
shooting yourself in the foot before starting.
This thread is a joke!
Sic gorgeamus a los subjectatus nunc.
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Aliquot
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Hi
Some on know FENTON'S REAGENT ?. This reagent turn phenol to catechol. Take a look to: http://www.h2o2.com/applications/industrialwastewater/fenton...
Where on WEB can I find the Vogel?
Aliquot
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JohnWW
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I have uploaded all of Vogel's works to rapidshare.com, and posted links for downloading them in the References section. Because Vogel himself has now
been dead for 50 years, and his works must have been originally authored by him more than 50 years ago, they are now out of copyright in my country
and many others. In spite of this, a few days ago I had to reupload one of his books, on Quantitative Organic Analysis, published in 1958, which had
been deleted as the result of some cretin squealing to rapidshare alleging breach of copyright. (The deletion was quickly detected because I keep a
tally of the total number and size of my premium-account uploads).
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