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All 4 posts Subject: Using pyridine to hydroxylate the 5-br vanillin Please login to post Down

lutesium
(Stranger)
07-21-04 00:59
No 520505
      Using pyridine to hydroxylate the 5-br vanillin

The idea is to lower the rxn times with an higher yield by useing pyridine for the hydroxylation of 5-br-vanillin.

I hope scravenging the halogen from the benzene ring via pyridine to form a cation which is open for the atttack of OH-

Swim added 15grms (n mole) of the aldehyde to 200mls H2O and trace of Cu powder (dunno why?). Then he measured 8mls (>n mole) of pyridine and added it to the suspension. Visible rxn formed a grayish solution with a white preticipate. Then 18gms of NaOH was measured, dissolved in 80mls H2O and added to the rbf while still hot. A visible rxn occured and the solution became orangeish. Then started refluxing under inert atmosphere. Still going on, planning for 3 hours.

Q. Can pyridine scravenge the 5- halogen and ease the attack of OH- ion?

Maybe using acetonitrile as a solvent, first refluxing the halo-ald. w/ pyridine then decomposing w/ OH- might be better?

Please help! I cant bear experimenting for days without any referenced mechanism and real result :( .!

hest
(Hive Adickt)
07-21-04 10:33
No 520571
      Cu/OH-

https://www.rhodium.ws/chemistry/iodovanillin.html
Use Cu (salt or metal) and NaOH. and use your time to optimise something with a low yeald.

lutesium
(Stranger)
07-21-04 16:21
No 520633
      hest: You're right to say that.

hest: You're right to say that. The Cu method is easy and high yielding. But I dislike refluxing 2 litres of H2O for 30 hours and trying to extract the HUGE rxn mixture. I just think that its impractical. But yes, its high yielding.
I still wonder if pryidine can cleave that Br?

Vaaguh
(Hive Bee)
07-22-04 23:26
No 520934
      concentrating

You can always evaporate some of the H2O before extracting.

Hippler

	https://the-hive.archive.erowid.org	the-hive@erowid.org



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	All 4 posts		Subject: Using pyridine to hydroxylate the 5-br vanillin		Please login to post		Down


		lutesium (Stranger) 07-21-04 00:59 No 520505				Using pyridine to hydroxylate the 5-br vanillin
						The idea is to lower the rxn times with an higher yield by useing pyridine for the hydroxylation of 5-br-vanillin. I hope scravenging the halogen from the benzene ring via pyridine to form a cation which is open for the atttack of OH- Swim added 15grms (n mole) of the aldehyde to 200mls H2O and trace of Cu powder (dunno why?). Then he measured 8mls (>n mole) of pyridine and added it to the suspension. Visible rxn formed a grayish solution with a white preticipate. Then 18gms of NaOH was measured, dissolved in 80mls H2O and added to the rbf while still hot. A visible rxn occured and the solution became orangeish. Then started refluxing under inert atmosphere. Still going on, planning for 3 hours. Q. Can pyridine scravenge the 5- halogen and ease the attack of OH- ion? Maybe using acetonitrile as a solvent, first refluxing the halo-ald. w/ pyridine then decomposing w/ OH- might be better? Please help! I cant bear experimenting for days without any referenced mechanism and real result :( .!



		hest (Hive Adickt) 07-21-04 10:33 No 520571				Cu/OH-
						https://www.rhodium.ws/chemistry/iodovanillin.html Use Cu (salt or metal) and NaOH. and use your time to optimise something with a low yeald.



		lutesium (Stranger) 07-21-04 16:21 No 520633				hest: You're right to say that.
						hest: You're right to say that. The Cu method is easy and high yielding. But I dislike refluxing 2 litres of H2O for 30 hours and trying to extract the HUGE rxn mixture. I just think that its impractical. But yes, its high yielding. I still wonder if pryidine can cleave that Br?



		Vaaguh (Hive Bee) 07-22-04 23:26 No 520934				concentrating
						You can always evaporate some of the H2O before extracting. Hippler

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