The Vespiary

The Hive => Methods Discourse => Topic started by: Bandil on May 08, 2002, 01:31:00 PM

Title: 3-methyl-1,4-dimethoxybenzene bromination
Post by: Bandil on May 08, 2002, 01:31:00 PM

After reading the excellent post by antoncho regarding sodiumethoxide production swim was getting interested.

If one accidently found alot of 3-methyl-1,4-dimethoxy lying around and wanted to brominate iodinate it. Would it be as simple as adding elemental bromine to a soln. of 3-methyl-1,4-dimethoxy? Swim was of course looking for the 4-methyl-2,5-dimethoxy-bromobenzene as a product, so he could fool around with some acetone enolate and make some 4-methyl-2,5-dimethoxy-P2P... Or are the ring substitutens arranged so that the bromine would attack elsewhere?

Thanks
Regards
Peter

Title: Shameless plug: http://www.rhodium.
Post by: yellium on May 08, 2002, 02:31:00 PM

Shameless plug:

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

http://www.erowid.org/library/books_online/pihkal/pihkal023.shtml (http://www.erowid.org/library/books_online/pihkal/pihkal023.shtml)

https://www.thevespiary.org/rhodium/Rhodium/chemistry/stp.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/stp.html)

But I guess BuLi and POCl3 are out of reach, otherwise you wouldn't want to brominate it...

Title: NBS works so how about elemental bromine?
Post by: Bandil on May 08, 2002, 03:06:00 PM

The first post(i think it was the first) said a bromination of 3-methyl-1,4-dimethoxybenzede yeilded the correct positioned brominated product. Could elemental bromine be used insted? Swim would think so, but is quite interessted in the opinion of the other bees.

After the bromination swim was thinking of the reaction with acetone w/ sodiumethoxide to give the corr. P2P. Is that reaction as easy as adding the NaOCH2CH3 to acetone and carfully adding the brominatied agent?

Thanks alot!

Regards
Peter

Title: See preparation of DESOXY (#52) to get the feel ...
Post by: yellium on May 09, 2002, 08:42:00 AM

See preparation of DESOXY (#52) to get the feel for how to deal with brominations with bromine.

http://www.erowid.org/library/books_online/pihkal/pihkal052.shtml (http://www.erowid.org/library/books_online/pihkal/pihkal052.shtml)

Regarding brominations: keep in mind that you'll always have some stuff dibrominated, and some stuff not brominated. To increase the fraction of monobrominated stuff, some synths use 1.05 or 1.1 equivalent bromine instead of 1.0. Also, keep your math straight! Once, I did a bromination with 2.0 equivalent bromine instead of 1.0. Aaaargh!

An other option is to try to make the aldehyde with a grignard, and then follow the traditional route. Grignard will be difficult to start, if at all.