The easiest synth of benzaldehyde from toluene

[Antoncho]

Ladies and gentlemen!

This is from our Russian chemforum, by courtesy of Babayka.

Having done a quick search, i found that there once was an inquiry of this synthesis on the Hive, unfortunately, no info was found at that time and the project was disregarded.

IMHO, it is the coolest synth of benzaldehyde there ever was. The description is not as detailed as it could bee but all the important points are here.

Synthesis of benzaldehydes from toluene and its derivatives. (note that obviously substituded toluenes may bee used too)
...Synthesis of benzaldehyde and its derivatives by oxidation of the corresponding toluenes is an important industrial process in pharmaceutic drug synthesis.
Oxidation of -CH3 group to -CHO is carried w/MnO2 in presense of sulfuric acid. In case if MnO2 is present in excess, aqueous acid is used and if a stoichometric quantity of MnO2 is taken, conc. H2SO4 is emloyed.
If the rxn is carried out at temp's below 40 C, aldehydes are formed, however, if its temp's allowed to rise to 60-70 C, the main product is benzoic acid.

,

Antoncho

[Rhodium]

This is true. However, for good yields a special form of activated MnO2 must be used (finely divided), but I have no exact prep details.

[UTFSE]

maybe ref to "Transactions of the Faraday Soceity"-
just remember it from the past. nothing specific.
always appreciate your time and consideration

[Osmium]

I got a better one  

toluene ----> benzaldehyde in 95%

Benzaldehyde

Ferrous-Copper Catalyst: Toluene (7.6 g.), water (35 ml.), ferrous sulphate (0.110 g.) heptahydrate, cupric acetate (0.072 g.) and methanol (8 ml.) are placed in a 250 ml. reactor.

Sodium persulphate (47.05 g.) in an aqueous-methanol solution of sodium persulphate is added slowly to the mixture which is maintained at 70.degree. C., in an atmosphere of nitrogen and under agitation.

The organic phase is separated after two hours and the aqueous phase is extracted with ethyl ether.

The combined organic phases are distilled to afford 8.29 g. (95% yield) of very pure benzaldehyde (compared against a pure sample).

US-Pat 4,146,582

[obituary]

can oxone be used in place of the persulfate?  what about a solution of caro's acid? (yes, that's extreme- just asking though)

[PolytheneSam]

Here's a list of related patents: 

Patent US613460

Patent US650332

Patent US661872

Patent US677239

Patent US698355

Patent US780404

http://www.geocities.com/dritte123/PSPF.html

[ZZACk]

NICE Osmium!
Go Ugly Early

[foxy2]

Cerium-catalyzed selective oxidation of alkylbenzenes with bromate salts.    
Ganin, Eyal; Amer, Ibrahim   
Synth. Commun.  (1995),  25(20),  3149-54.

Abstract
Ce(IV) NH4NO3 (CAN)-catalyzed oxidn. of alkyl aroms. with KBrO3 affords aldehydes, ketones, carboxylic acids or alcs. in varying yields depending upon reaction conditions and substrate.  E.g., 4-MeC6H4Me is treated with CAN and KBrO3 in 1,4-dioxane/water soln. to give 4-MeC6H4CHO in 70% and 4-MeC6H4CO2H in 20%.
Do Your Part To Win The War

[Aurelius]

Foxy, will that work for PAA from ethylbenzene?

[Greensnake]

>will that work for PAA from ethylbenzene?

Probably not, these oxidations are specific for benzylic position (not terminal), so acetphenone will be formed.

[Disciple]

I was wondering if anyone has had any success with the following method posted by antoncho previously, and if anyone has any idea on the MnO2 preparation.

It seems to me that it shouldn't be that hard to come up with other methods with fairly easy precursors.
I'm hoping to get my hands on some stuff in the near future to give this a go.

Synthesis of benzaldehydes from toluene and its derivatives. (note that obviously substituded toluenes may bee used too)
...Synthesis of benzaldehyde and its derivatives by oxidation of the corresponding toluenes is an important industrial process in pharmaceutic drug synthesis.
Oxidation of -CH3 group to -CHO is carried w/MnO2 in presense of sulfuric acid. In case if MnO2 is present in excess, aqueous acid is used and if a stoichometric quantity of MnO2 is taken, conc. H2SO4 is emloyed.
If the rxn is carried out at temp's below 40 C, aldehydes are formed, however, if its temp's allowed to rise to 60-70 C, the main product is benzoic acid.

[Mountain_Girl]

If you had typed 'MnO2' in the FSE you would have found:

Post 296395 (missing)

(hest: "You need 'activated' MnO2.", Newbee Forum) (from MnCl₂).
(I could have just said UTFSE but since I'm thinking of risking all good karma by asking a MBRP related question at Stimulants it would feel hypocritical)

MnO₂ can also be prepared from MnSO₄ as described in later versions of Vogel (not 3rd).
(Might look it up and post it to make up for an anticipated karma loss..)
Mountain Boy

[blondie]

Preparation of activated Manganese Dioxide at the bottom of this doc.

https://www.thevespiary.org/rhodium/Rhodium/chemistry/oxycodone.html

[flipper]

In case if MnO2 is present in excess, aqueous acid is used and if a stoichometric quantity of MnO2 is taken, conc. H2SO4 is emloyed.
If the rxn is carried out at temp's below 40 C, aldehydes are formed.

Is this solventless?
What is stoichometric?
How much H2SO4 is used in both stoichometric and in excess reactions?
In what ratio is MnO2 : Toluene reacted to get the best yields?
What are the ratios for the stoichometric and excess reactions? 
What are the yields?
Where can I find information about this synt?

Please I'm very interrasted in this synt. I really thankful for the person with the answers.  

[Rhodium]

Introduction to stoichometry:

http://www.sparknotes.com/chemistry/stoichiometry/intro

You can find a procedure by using either www.scirus.com or one of the patent search engines suggested on TFSE page.

[flipper]

93 g Toluene + 87 g MnO2 + ? g aq H2SO4 ---> 106 g Benzaldehyde.

Is this without a solvent and how much H2SO4 is used? Must the reaction have a specific PH?

[Rhodium]

General Method for the Preparation of Benzaldehydes
J. Med. Chem. 27, 1111-1118 (1984)

Activated MnO2 (21.7 g, 0.25 mol) and 200 mL of benzene were refluxed for 2 h in a Dean-Stark apparatus. Then the benzyl alcohol (0.05 mol) was added and the solution was refluxed for 24 h. The reaction mixture was filtered and the solvent was removed. The residue was recrystallized in methanol/ether or acetonitrile to afford the pure benzaldehyde.

General Method for the Preparation of Benzaldehydes
JACS 77, 4399-44901 (1955)

A solution of 10.9 g (0.1 mol) of benzyl alcohol in 1000ml of solvent (1) was stirred at room temperature with 100g of manganese dioxide. When the reaction was over (2), the solution was filtered. The solid was washed with chloroform and ethanol and the washings were added to the original filtrate, the solvent evaporated and the residue distilled to give the benzaldehyde.

(1) CHCl3, DCM, Et2O and petroleum ether are all okay, with little difference in yield.
(2) After one hour, the yields are 55-70% and after 24h 75-90% depending on the benzaldehyde.

[GC_MS]

SWiM has a nice collection of books, viz Meyer's Synthese der Kohlenstoffverbindungen. It's a collection of prepartion methods, described very shortly, with references to the original publications. Here are the data for benzaldehyde:

1) 100 g benzene + 45 g AlCl3, HCl, 40-50°c + CO for several hours. Pressure is 90 atm. Yield: 30 g --- 100 g AlCl3, 1 g TiCl4, 190 g benzene, 30-40°C + CO till 60 atm. [1,2]
2) 60 g benzene, 60 g AlBr3, 12 g CuCl2 + CO, HCl (2:1), first cool down with water, then 5h at 20°C. Yield: 90%. Or with AlCl3, Cu2Cl2, 7 hours at 45°C + CO, HCl [3,4]
3) 4 mol benzene, 1 mol Ni-carbonyl, 4 mol AlCl3, stand for several days. Add water. Yield: 20% [5].
4) 150 g benzene, 90 g Hg 43-45°C in 40 min + 120 g AlCl3, 15 g AlCl3 + 6 H2O, 15 g Al(OH)3. Stand for 3h. Yield: 68% oxime + 1.2 g aldehyde [6].
5) PhMgBr, ether + HCOOH or 3 mol formic acid ester -50°C. Better is + 1/2 eqv ortho-formic acid. Yield: 93% [7,8,9].
6) 6 g PhMgBr, ether, 2 g methylcarbylamine, ether 0°C stand for 12 hours. Or + methylformanilide, or + ethoxymethyleneaniline, boil shortly. Yield: 46% [10,11,12].
7) benzene, HCl, HCN, AlCl3, 100°C [13].

-----------------------------

1 DRP 281212
2 EP 334009
3 GATTERMANN, Ann 347 (1906) 351
4 HEY, J Chem Soc London (1935) 72
5 DEWAR, JONES, J Chem Soc London 85 (1904) 213
6 SCHOLL, Ber 32 (1899) 3498
7 ZELINSKY, Chem Ztg 28 (1904) 304
8 GATTERMANN, MAFFEZZOLI, Ber 36 (1903) 4152
9 WOOD, COMLEY, J Chem Soc Ind 42 (1923) 429
10 SACHS, LOEVY, Ber 37 (1904) 875
11 BOUVEAULT, Bull Soc Chim France (3) 31 (1904) 1327
12 MONIER, WILLIAMS, J Chem Soc London 89 (1906) 275
13 HINKEL, AYLING, J Chem Soc London (1932) 2793

-----------------------------

SWiM added this to "complete" the library of benzaldehyde synthesis possibilities. As you see, all routes start with benzene or PhMgBr. The brevitas is typical for Meyer's work. If you want to know more about a particular method, you have to look up the mentioned references.
WOMAN.ZIP: Great Shareware, but be careful of viruses...

[ragnaroekk]

LEGO, did the authors mention details on the workup? I remember to have read otherwise a description of the workup of a montmorillonite K10 reaction (solventfree) and it sounded to me quite painful. The catstray properties "sucking up and keep enclosed" of the clay - which are probably responsible for the selectivity of the reaction - seemed to have some drawbacks.

If there is a easy way to wash the product out of the montmorillonite - without very high vacuum or similar - thus would perhaps make this way intersting. Still the ratio of reactands (tetralin to KMnO4/K10 is 1 to 17.... w/w) lets doubt the up-scalability.


important
But please don´t stop posting those findings , also if they lack good yields or look otherwise inconveniant! They are worth gold for showing up principles and giving inspiration where to look, where to search for what.
Yes?


RAgnArOeKk

[Tdurden969]

Anyone seen this patent? Yields are kinda lame - but it's quick and dirty. Os' is better - but if you have problems with n2...

process for the production of benzaldehyde by catalytic liquid phase air oxidation of toluene, preferably with 40-50% selectivity.

Patent US6495726