ItalianChemist - 28-4-2011 at 05:19
Hi!
I wanna try Hofmann rearrangement of pthalimide, because I need anthranilic acid for making some esters, with the following procedure:
prepare a hypobromite solution dissolving 4,2ml of bromine in a solution of 16g of sodium hydroxide in 60ml of water.
Then add 11,8g of phtalimide prepared from pthalic anhydride and an excess of urea and purified by sublimation, and 11g of NaOH.
Warm the solution on a water bath at 70°C for 15 minutes, then add 30ml of concentrated hydrochloric acid and 10ml of glacial acetic acid.
Filter the precipitate on Buchner and redissolve in boiling water with some carbon activated.
Has someone tried this one? I'm not sure for the yeld...but if reach a good final product I'll write a post on prepublication.
Jor - 28-4-2011 at 05:30
I have never done it, but you must cool the solution very efficiently when adding bromine to the NaOH-solution, as the hypobromite-ion easily
disproportionates to bromide and bromate. I would say keep the solution as close to 0-5C as possible.
ScienceSquirrel - 28-4-2011 at 05:44
The search engine is your only friend;
http://www.sciencemadness.org/talk/viewthread.php?tid=10272
ItalianChemist - 28-4-2011 at 06:04
Ops...I haven't seen the discussion!
yes I will keep the temperature very low, thanks!