# Benzaldehyde synthesis from benzyl alcohol. 1 kg Scale.



## William Dampier (Jul 21, 2021)

*Reaction scheme:*​


​*Synthesis:*
1. A mixture of the benzyl alcohol (1000 g) and conc. H2SO4 (930 g) in DMSO (3000 ml) was stirred 2 hours under reflux conditions.
2. The mixture was then cooled to r.t., and brine (4000 ml) was added.
3. The organic phase was extracted with CH2Cl2 (3000 ml), and the organic layer was dried (Na2SO4), filtered, and concentrated under reduced pressure.
4. Benzaldehyde was obtained in good purity, which does not require additional purification.​


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## Jack

Sci-Hub | Sulfuric Acid-Promoted Oxidation of Benzylic Alcohols to Aromatic Aldehydes in Dimethyl Sulfoxide: An Efficient Metal-Free Oxidation Approach | 10.1055/s-0037-1609149


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## The Silent Chemist

2. The mixture was then cooled to r.t., and brine (4000 ml) was added.

Are they washing it here and then separating the 2 layers in a sep funnel or putting the whole 4000ml worth of brine in at once and leaving it in there for the next step
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3. The organic phase was extracted with CH2Cl2 (3000 ml), and the organic layer was dried (Na2SO4), filtered, and concentrated under reduced pressure.

I assume in this step the reaction mixture is washed with three portions of 1000ml DCM and then those are pooled together and reduced under a vacuum after being dried with Na2SO4 and filtered


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## G.Patton

The Silent Chemist said:


> Are they washing it here and then separating the 2 layers in a sep funnel



The Silent ChemistHi, this way is correct. You are right in the second statement.


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## The Silent Chemist

Im guessing MgSO4 can be used as a substitute to Na2SO4

Thank you for your response ! And thank you to the BB team


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## Fenster

This is a lot of sulfuric acid. I think a better route is dilute nitric acid with NaNO2 catalyst.


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