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The Hive => Chemistry Discourse => Topic started by: Azarius on April 27, 2002, 11:10:00 AM

Title: 2,5-dimethoxyphenylacetaldehyde
Post by: Azarius on April 27, 2002, 11:10:00 AM
SWIM has a few questions regarding this compound.

1. Fe/HCl redn. of the nitrostyrene gives this phenylacetaldehyde, but also has the danger of over-oxidation to the phenylacetic acid. Could the phenylacetaldehyde bee separated from any formed phenylacetic acid via steam distillation of the rxn mixture?

2. Does 2,5-dimethoxyphenylacetaldehyde polymerise on standing, as phenylacetaldehyde does?

3a. Am I correct in assuming the imine could be formed with anhydrous NH3 in MeOH and reduced in high yield with NaBH4 a la LaBToP?

3b. If reducing the imine with Al-Hg or Zn, should this bee done under basic or acidic conditions?

4. Any other comments?

Many thanks,
Azarius
Title: 4.Are you aware that the nitrostyrene can be ...
Post by: PrimoPyro on April 27, 2002, 11:15:00 AM
4.Are you aware that the nitrostyrene can be reduced straight to the end amine, instead of changing it to the aldehyde, then the amine?

                                                  PrimoPyro
Vivent Longtemps La Ruche!
Title: nitrostyrene redn.
Post by: Azarius on April 27, 2002, 11:20:00 AM
Yes.
Title: Ok, I was only checking. 1.
Post by: PrimoPyro on April 27, 2002, 11:38:00 AM
Ok, I was only checking.

1.You should be able to seperate it if you were to deprotonate the phenylacetic acid with alakali hydroxide, forming the nonvolatile salt. Steam distillation would likely remove the aldehyde, and leave the solid salt in the distillation flask.

I believe this was the procedure recommended to me by Rhodium for the seperation of phenylacetone from 2-phenylpropanal, which it was its originating source. He had recommended that the remaining 2-PP be oxidized to the carboxylic acid and deprotonated, followed by distillation of the product P2P, seperating them.

(That synthesis has yet to occur by the way, for those inquiring minds out there.)

                                                   PrimoPyro
Vivent Longtemps La Ruche!
Title: Check this procedure: http://www.rhodium.
Post by: Rhodium on April 27, 2002, 10:44:00 PM
Check this procedure:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/2ch.darzen.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/2ch.darzen.html)



It involves formation of the phenylacetaldoxime instead of the acetimine - I bet the yields will be much higher than with ammonia/NaBH4. Use acidic Al/Hg for the oxime. I believe all phenylacetaldehydes polymerizes on standing.
Title: acetaldoximes
Post by: Azarius on April 28, 2002, 02:23:00 PM
Thankyou PP, Mr. R... so the phenylacetaldehyde should bee used immediately/ASAP...

I was aware of the possibility of phenylacetaldoxime redn... I am preparing a 2C-H synthesis overview, and so am investigating all the routes I can find.

Many thankx,
Azarius