Sciencemadness Discussion Board

phenethyl bromide from bromobenzene?

conducter - 19-10-2007 at 16:23

Is it possible to make phenethyl bromide (2-bromoethyl)benzene from Bromobenzene?

not_important - 19-10-2007 at 17:57

Yes :

make the Grignard reagent from bromobenzene, add it to a slight excess of BrCH2CH2I (1-bromo-2-iodo-ethane) with good stirring.

chemrox - 20-10-2007 at 00:25

I like it but wouldn't the dihalo alkane be harder to come by?

Nicodem - 20-10-2007 at 00:51

Not_important, I don't think that would work. Unless you had in mind a Kumada coupling with an organometalic catalyst like described in the paper I recently uploaded: https://sciencemadness.org/talk/viewthread.php?tid=9310&...

chemrox - 20-10-2007 at 11:41

Isn't that where he was going? We all just read that paper, thanks to you.

Sergei_Eisenstein - 20-10-2007 at 13:16

I would try the following:

1) organomagnesium of halobenzene + ethylene oxide -> 2-phenylethanol
2) 2-phenylethanol + (several possible reagents) -> (2-bromoethyl)benzene

garage chemist - 20-10-2007 at 23:10

2-phenylethyl bromide is industrially made by free-radical addition of HBr to styrene. Anhydrous gaseous HBr and less than 30% styrene in an aliphatic hydrocarbon solvent (e.g. heptane) is used, at elevated temperature, and with a radical initiator (dibenzoyl peroxide, AIBN, etc...).
The product needs proper purification, although almost no 1-phenethyl bromide is formed in the reaction.

Antwain - 20-10-2007 at 23:27

I cant imagine that getting the anhydrous HBr is going to be especially easy if you can't buy it in a pressurised bottle

chemrox - 20-10-2007 at 23:59

I would follow Sergei's example if I hadn't been able to buy it. Acros, Spectrum, Alfa Aesar and etc. all have it. Not so dear as to make using a gaseous epoxide worthwhile... you would need a hood with good evacuation and I suppose there's a place you could get a lecture bottle of it filled but I've no idea where that would be. All my gasses come from a welding supplier.