Hello Jiang,
I don't know of a commercial supplier, but it should be possible to
exchange at low pH (0-1) in the presense of excess labeled water.
Carboxylic acids have been prepared in this manner (Van Etten? Methods in
Enzymology). Let me know if you need more precise references.
I might try using HI as the acid to minimize the chances of
displacing the iodo group, but hydrolysis (loss of iodide) might still be a
problem. I have never seen a hydrolysis rate versus pH study for these
compounds, but one may exist. I would expect that the loss of label at pH
7 is slow.
Good Luck,
Chris
weather: about a week of Indian Summer has just finished up. Highs in the
80's.
Christopher Halkides
Dept. of Chemistry, UNCW
601 S. College Road
Wilmington, NC 28403-3297
(910) 962-7427