Sciencemadness Discussion Board

toluene --> benzaldehyde

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TheVoid - 6-6-2018 at 18:33

If your concern is the product not the science the easiest way to benzaldehyde beside buying it directly is reacting benzyl alcohol with bleach and Hcl acid as seen on youtube, the yields are remarkable if u can make a judgment call on the completion of the reaction. i made an amount of various aldehydes this way.

Sherlock Holmium - 19-6-2018 at 05:29

I suggest making benzyl chloride via radical chlorination and a subsequent sommelet reaction to form the benzaldehyde, I imagine this procedure would give far superior yields, although working with benzyl chloride is not the nicest thing in the world.

draculic acid69 - 14-8-2018 at 19:58

Has anyone actually tried the destructive distillation of calcium benzoate and calcium formate under vacuum or inert atmosphere (or it oxidized back to benzoic acid ).
Would definitely be worth trying.

sykronizer - 20-11-2018 at 22:24

If you consult more lit on that reaction, you will find that it only works for aliphatic and low molecular weight aldehydes....in any case it is stated outright that this is not a preparation method.

Refinery - 8-5-2020 at 09:27

Could sodium persulfate be substituted with sodium percarbonate in similar context?

TriiodideFrog - 2-10-2020 at 01:51

You can just purchase some bitter almond oil. It is almost pure benzaldehyde.

Fyndium - 13-10-2020 at 07:15

Quote: Originally posted by draculic acid69  
Has anyone actually tried the destructive distillation of calcium benzoate and calcium formate under vacuum or inert atmosphere (or it oxidized back to benzoic acid ).
Would definitely be worth trying.


Should definitely give a try.

I could make calcium formate instantly at hand stuff.

Calcium benzoate then.. It's not available, but sodium benzoate is.

Sodium Benzoate has solubility of 62-71g/100mL (0-100C).
Calcium Chloride has high solubility.
Calcium Benzoate has solubility of 2-9g/100mL (0-100C).

Na Benzoate + Ca Chloride = Ca Benzoate (s) + NaCl.

So the dry distillation should be performed under vacuum? Does this effect the decomp temp or is it just to protect the expected aldehyde from oxidizing?

I will put this to my to-do list. When I get time, I'll test it out, unless someone reports here that it's already been debunked.

Fyndium - 16-10-2020 at 15:13

Persulfate is used in many oxidations for BzH. What is the mechanism in this reaction and could it be substituted with, for example percarbonate or perborate instead?

Cou - 17-11-2020 at 19:40

Bromobenzene and DMF are not watched chemicals, and can be used to make benzaldehyde by the Bouveault aldehyde synthesis.
there's a limit on how far back the DEA can go in limited precursors. At a certain point it's no longer profitable.

Gualterio_Malatesta - 15-12-2020 at 07:50

Hey, guys!

There's this paper where they oxidize toluene to BA electrolytically in the presence of NaNO3 and catalytic amounts of H2SO4.

Toluene (1ml) is mixed with DCM (25ml) then water and sulfuric acid is added (5.4 ml of 37% sulfuric acid diluted with 44.6 ml of distilled water to obtain 50 ml of 0.46 M solution of sulfuric acid) and 1.18 gm of KNO3. Subsequent stirring of this solution creates an emulsion and current is applied.

Since I didn't have DCM I used isopropyl alcohol (they also tried MeOH in the paper, so I thought IPA would be ok in this reaction).

The anode (+) was carbon and cathode (-) was stainless steel.

When current (12V, 2.2A) was applied to the reaction mixture (toluene, IPA, KNO3,H2SO4 ) both anode and cathode produced a lot of gas bubbles (colorless and odorless). The temperature was kept between 30 — 40oC

The smell of toluene completely disappeared after approx 1 hour.
Reaction mixture was filtered from carbon residue to obtain homogenous dark yellow liquid with the smell of IPA and something weird (not BA).

What do you think was the gas from the electrodes and what could have this reaction yielded in the end?

[Edited on 15-12-2020 by Gualterio_Malatesta]

Sedit - 9-1-2021 at 21:19

Quote: Originally posted by Gualterio_Malatesta  
Hey, guys!

There's this paper where they oxidize toluene to BA electrolytically in the presence of NaNO3 and catalytic amounts of H2SO4.

Toluene (1ml) is mixed with DCM (25ml) then water and sulfuric acid is added (5.4 ml of 37% sulfuric acid diluted with 44.6 ml of distilled water to obtain 50 ml of 0.46 M solution of sulfuric acid) and 1.18 gm of KNO3. Subsequent stirring of this solution creates an emulsion and current is applied.

Since I didn't have DCM I used isopropyl alcohol (they also tried MeOH in the paper, so I thought IPA would be ok in this reaction).

The anode (+) was carbon and cathode (-) was stainless steel.

When current (12V, 2.2A) was applied to the reaction mixture (toluene, IPA, KNO3,H2SO4 ) both anode and cathode produced a lot of gas bubbles (colorless and odorless). The temperature was kept between 30 — 40oC

The smell of toluene completely disappeared after approx 1 hour.
Reaction mixture was filtered from carbon residue to obtain homogenous dark yellow liquid with the smell of IPA and something weird (not BA).

What do you think was the gas from the electrodes and what could have this reaction yielded in the end?

[Edited on 15-12-2020 by Gualterio_Malatesta]


If you are making Nitric acid buffered in situ which is part of what I believe this reaction is doing last thing you want is to use an Alcohol. IPA might be a bit more stable than some alcohols but no way would I put faith in it.

Maybe... idk, doubtful as well but Ethylacetate? Idk, probably not.
DCM is so easy to get almost everywhere I know of why not just use that? I'm considering this. Don't have any Nitrate though. Have Ammonia Nitrate so suppose I could just make some. Needed that for Ammonia Generation, if I get around to it I will just save the waste and see about doing this reaction.

Gualterio_Malatesta - 9-2-2021 at 01:08

Quote: Originally posted by Sedit  



DCM is so easy to get almost everywhere I know of why not just use that?


I tried DCM (and the authors mention it too and with good yields), but the reaction temp is 30-40 deg, so DCM basically boils away.

Triflic Acid - 31-3-2021 at 11:17

Has anyone thought of the messy one step version where you just dichlorinate toluene to benzal chloride. I guess if you were strategic about it, you could turn the toluene into benzal chloride by putting the temperature at the boiling point of benzyl chloride. Then, first the toluene goes into the vapor phase and forms benzyl chloride under UV which promptly condenses. After most of the toluene is gone, the temperature is ramped up with a sand bath to the boiling point of benzyl chloride, and this undergoes a second chlorination to give benzal chloride. Just add water to get benzaldehyde.

Opylation - 4-6-2021 at 10:15

This isn’t toluene, but phenol (made easily from salicylic acid) can be reacted with chloroform and sodium hydroxide in the Reimer-Tiemann reaction to form salicylaldehyde. This can be reacted with zinc powder to form benzaldehyde :)

SuperOxide - 4-6-2021 at 13:32

Quote: Originally posted by Opylation  
This isn’t toluene, but phenol (made easily from salicylic acid) can be reacted with chloroform and sodium hydroxide in the Reimer-Tiemann reaction to form salicylaldehyde. This can be reacted with zinc powder to form benzaldehyde :)


Hmm, I'm right in the middle of making some phenol to mess around with. I have all of those chemicals, I may give this a shot (after I do some research, of course).
I'll research it myself before I decide if I'll give it a go, but if you have any specific resources/links that you suggest, do share.

Have you tried that synthesis route before?

Opylation - 4-6-2021 at 14:55

I don't have any experience going through the procedure, but the salicylaldehyde synthesis via phenol and chloroform is a standard method. So is the dehydroxylation of benzene with Zn powder.



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