Author Topic: The easiest synth of benzaldehyde from toluene  (Read 61175 times)

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  • Guest
Benzaldehydes with activated MnO2
« Reply #40 on: December 30, 2003, 11:10:00 PM »
Good yields are 75-90% according to the procedure in

Post 354314

(Rhodium: "General Method for the Preparation of ...", Chemistry Discourse)
(This thread!)

Preparation of activated MnO2 (Not MnO4!):

Post 352497

(Mountain_Girl: "Activated MnO2", Chemistry Discourse)

Post 352508

(blondie: "activated MnO2", Chemistry Discourse)


  • Guest
More on Toluene -> Benzaldehyde
« Reply #41 on: December 31, 2003, 04:09:00 AM »
In addition to the above, please check out the following references, all of which should be pertinent to the MnO2/H2SO4 oxidation of toluene to benzaldehyde:

Reactant: Toluene
Reagents: Sulfuric Acid (H2SO4), Manganese dioxide (MnO2)
Product: Benzaldehyde

Patent DE175295

Patent DE101221

Patent DE107722

J. Chem. Soc. 91, 263 (1907)
Zh. Obshch. Khim. 4, 936-940 (1934)
Chem. Zentralbl. 106, II, 3750 (1935)
Chem. Zentralbl. 76, I, 359 (1905)

Post 244957

(Chemikaze: "Benzaldehyde via MnO2 oxidation of toluene", Novel Discourse)

Post 463350

(Antoncho: "A great piperonal patent", Novel Discourse)

Post 208782

(PolytheneSam: "Re: The easiest synth of benzaldehyde from toluene", Chemistry Discourse)

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(Assholium: "åñòü êàêèå-òî ìûñëè?", Russian HyperLab)

Post 224776

(fructose: "P2P - 100% OTC !?!", Chemistry Discourse)


  • Guest
« Reply #42 on: March 08, 2004, 06:18:00 PM »

Post 437235 (missing)

(Organikum: "B-dehyde", Stimulants)


  • Guest
Benzoic acid to benzaldehyde or benzene
« Reply #43 on: March 09, 2004, 02:57:00 AM »
I like the ref very much, thank you Organikum and Lugh. Those tube furnaces don't look that scary after all. ;)  Here is the second part of the article series:

Deoxygenation of benzoic acid on metal oxides. 2. Formation of byproducts.
de Lange, M. W.; van Ommen, J. G.; Lefferts, L.
Applied Catalysis, A: General, 231(1-2), 17-26 (2002).  Journal written in English.
CAN 137:142127  ISSN 0926-860X

Benzene, benzophenone, toluene and benzyl alc. are byproducts in selective redn. of benzoic acid to benzaldehyde on ZnO and ZrO2 catalyst.  The pathways to the byproducts are discussed and a complete overview of the reaction network is presented.  Benzene and benzophenone are products of the decompn. of the strongly adsorbed benzoic acid at elevated temps.  Toluene is formed by deoxygenation of benzaldehyde at O vacancy sites.  Direct hydrogenation of benzaldehyde yields benzyl alc.  Selectivity to byproducts is not only detd. by the reaction temp., but also by the degree of surface redn. and the difference in adsorption strength between reactant and product.  At <360 Deg, benzoic acid forms a benzoate layer which is stable and prevents readsorption of benzaldehyde.  Redn. of the catalyst by H leads to a small no. of O vacancy sites which deoxygenate benzoic acid to benzaldehyde, and as a result, selectivity to benzaldehyde is very high (>95%).  Higher temps. induce decompn. of the benzoate layer to benzene, and more importantly, enhance the degree of redn. of the catalyst, which results in the formation of toluene from benzaldehyde.


  • Guest
Benzoic acid to benzaldehyde by electrolysis
« Reply #44 on: March 09, 2004, 03:11:00 PM »
The not so new  ;D  

Patent DE123554

from 1899 describes the electrolytic conversion of benzoic acid to benzaldehyde by an interesting way.

It describes that 45 to 50 parts finely powdered benzoic acid are intimately mixed with 55 to 50 parts of graphite, pressed under heat (100°C, 30atm) and this is used as cathode in an electrolytic cell. The cathode is placed in an glascylinder which is surrounded by an cylindrical lead anode (or platinum). Electrolyte is 20% H2SO4 saturated with benzoic acid at 20°C. Water is permanently refilled near the anode at the bottom of the cell by an tube, voltage is 12V to 15V and current density is 1,5Amp per dm2 of cathode surface. Benzaldehyde separates on the surface and is removed from time to time whilst water is refilled, the cathode decomposes by time and the graphite precipitates at the bottom of the cell.

Dont say thats far out. It is much easier as it looks as compressing the benzoic/graphite in a steeltube cannot be so hard - a threaded rod or a jack will work fine I suppose. No diaphragm needed, nor exotic electrolyte.......

The patent says the method works for oxidation as reduction the same.
Examples named but not given are:

- carboxylic acids overall
- paraformaldehyde
- aromatic nitrogenous compounds
- alkaloids
- .....

- anthracene
- cellulose


  • Guest
PhCHO from toluene, air and metal catalyst
« Reply #45 on: March 09, 2004, 11:29:00 PM »
The best one I ever saw and only one tried of all the many ways to oxidize toluene to benzaldehyde is found in The Journal of Chemical Education from around 1953 if my memory is correct. If someone who has acess to this journal could find this it would surely interest a lot of people.

Air is carrier gas and O2 source which is bubbled through boiling toluene (use bubble counter for determining flow rate) and passed through a vertical stainless steel tube packed with catalyst at 350C and then into a condenser. Very little side products if temperature is kept stable. The article has drawings for a tube heated in a molten lead bath but it is much easier to wrap the tube with NiCr wire (toaster or blow dryer) about 300 watts controlled with a triac type dimmer and monitored with a thermocouple (Type K from a water heater flame sensor).

The article is very good and compares many different metal catalysts (Fe, Zn among the simple ones and some more exotic) with yields and reaction conditions. I made Cerium Molybdate, coated alumina pellets with it and got about 85% molar yield.

The beauty of the tube method is continuos production with very little work. A 1/2 X 24 inch tube gives about 1 liter a day and runs for 2 weeks or so before regeneration of the catalyst is required.

I tried the JACS website to find the article but since I am no longer a member the Journal of Chemical Education is unavailable to to me.


  • Guest
Two articles on catalytic air oxidation of toluene
« Reply #46 on: March 14, 2004, 11:53:00 PM »
I was unable to find the article from the Journal of Chemical Education that Bio mentions. However, in a private communication he indicated that the information was originally published in Industrial and Engineering Chemistry, and I was able to find a couple of articles on that topic.

Bio said:
"Parks is the author and the second article has the drawing I refered to. I believe the JCE article must have been a compilation of Parks work. I did not see Cerium Molybdate or the higher yields on the list in a quick look just now, so this must be a later article. That's why I picked it as catalyst. It is very easy to make from Cerium Nitrate and Molybdenum ammonium something or other."

I performed a further search, searching for Parks as author and cerium or ceric catalyst as keywords; I turned up an additional article about air oxidation of xylene to toluic aldehyde and phthalic anhydride. There were no articles by that author using a cerium/molybdenum catalyst.

Perhaps I will be able to find the JCE article later, now that I know what name to look for. Here are the articles themselves (Rhodium, please mirror if they're worthy):


  • Guest
benzaldehyde from toluene
« Reply #47 on: March 22, 2004, 05:59:00 PM »
Great find Polverone. It's been so long ago that I forget most of it but since these articles came way before the days of computers the indeces are not always that complete. I may have adapted the Cerium Molybdate from one of the Xylene oxidation articles. These are also very good for understanding the basic parameters required to design a catalyst loaded furnace tube and Parks gives enough data on space time etc. that one may easily design one in the size required by the materials at hand. I wonder if Parks was affiliated with a major company because he reveals more information than is usually found in these types of patentable topics. Many Bees will enjoy the Journal of Industrial and Engineering Chemistry as it contains practicle information related to the initial scale up experiments on most important reactions progressing from the bench to something more useful and often actually simpler than the parent procedures. The many articles on Chloromethylation with formaldehyde etc. come to mind.


  • Guest
H2O2 toluene oxidation (vanadium catalyzed)
« Reply #48 on: March 30, 2004, 02:07:00 AM »
I am refering here to moo´s post about the (im)possibility to use H2O2 in the oxidation of toluene.

The earliest example was the oxidation of toluene to benzaldehyde. A divided cell was used and the anode was used to oxidize Mn(II) to Mn(III) in sulfuric acid while the graphite cathode was used to reduce oxygen to hydrogen peroxide. The oxidation of toluene was carried out in situ in the catholyte in the presence of V(IV) as a catalyst while the Mn(III) was reacted with toluene external to the cell after the electrolysis


January 1999 Vol. 4 No. 1
Electrogenerated Hydrogen Peroxide -
From History to New Opportunities
by Derek Pletcher

the reference for the above:
- J-J. Jow, A-C. Lee and T-C. Chou, J. Applied Electrochem., 17 (1987) 753

somebody can look this up and post it here?
Thus would be GREAT!

Ok, the persulfate part is wellknown and not new at all, but the hydrogen-peroxide/vanadium(IV/V) part is new I think (but I maybe wrong of course). Anyways this sounds like a possible method to produce benzaldehyde from toluene with excellent selectivity and in good yields by using H2O2 and a catalyst - the electrolytic part may be neglectable for our purposes.


EDIT: I just realized that this correspondends to the article LabTop posted (courtesy TurdenXXX) - as the described method of bubbling oxygen over the cathode will of course produce hydrogen peroxide. Nevertheless, the question to be asked is: Will this work without in-situ generation of H2O2? If yes - and I think it will work - catalyst preparation and conditions optimized for a non-electrolytic reaction?



  • Guest
In regards to Organikum's post regarding ...
« Reply #49 on: August 09, 2004, 10:30:00 AM »
In regards to Organikum's post regarding Patent

Patent DE123554

about electrolytic conversion of benzoic acid to benzaldehyde, the patent says the method works for oxidation as reduction the same. So cant we do the reverse and oxidise tolune to benzaldehyde at the anode?

If toluene can be aquired and one would originally oxidise this to benzoic acid via KMnO4 to benzoic acid, it seems more practical to electrolytically oxidise to benzaldehyde.


  • Guest
No. This says you can oxidise benzaldehyde to...
« Reply #50 on: August 09, 2004, 08:46:00 PM »
No. This says you can oxidise benzaldehyde to benzoic acid this way.


  • Guest
3,4,5-Trimethoxytoluene to 3,4,5-TMBA (92%)
« Reply #51 on: September 16, 2004, 03:00:00 AM »
The Selective Liquid-Phase Oxidation of 3,4,5-Trimethoxytoluene to 3,4,5-Trimethoxybenzaldehyde
Nobumasa Kitajima, Kazuya Takemura, Yoshihiko Moro-Oka, Tadatsugu Yoshikuni, Mitsuo Akada, Yoshihisa Tomotaki, and Masatoshi Taniguchi

Bull. Chem. Soc. Jpn., 61, 1035—1037 (1988)


The selective liquid-phase oxidation of 3,4,5-trimethoxytoluene to 3,4,5-trimethoxybenzaldehyde, an important chemical intermediate for medicine production, was developed; when 2.0 mmol of the reactant was heated at 110°C for 2 h in an autoclave under 3 atm O2 with 10 ml of acetic acid in the presence of 0.75 mmol of Co(OAc)2-Mn(OAc)2 (3:1 mole ratio), a 92% yield of the aldehyde was obtained.