Yesterday, I prepared a solution of 72 gr KBr in 130 ml dH2O, added 3 icecubes followed by addition of 66 gr 93% H2SO4. The beaker was cooled in an ice bath, and 45 gr (0.5M) DL-lactic acid was added. The mixture sat there for 4 hours, stirring once in a while.
Then I started fucking up (haven't had much sleep lately
), so instead of neutralising the acid with NaHCO3, filtering and distilling the water off, I proceeded to add an excess of ethanol, trying to make the desired ester in situ.
I began to smell the ethyl bromide I've just made
so I started to neutralize the acid to pH 4 with bicarb. Then the ppt. salt was filtered with suction (quite an amount) and the yelloworange filtrate was distilled. First came a small amount of EtBr, then ethanol, then H2O, and it left a offwhite solid residue in the distilling flask .
It's still in the flask, haven't got around to checking its mp.
Normally under these conditions lactic acid should brominate, why hasn't it? I used an excess of HBr and H2SO4, according to "Morrison & Boyds Org. Chem." the most desirable way to brominate alcohols, and I kept it well cold to avoid acrylic acid formation.
Has it been done before using aq. HBr ? any refs?