1 ml of concentrated HCl (36%) added to 10.65 ml H2O. 614 mg of glutathione was dissolved into this and was stirred on ice.
138 mg of sodium nitrite (NaNO2) were added to the acidic glutathione solution while stirring vigorously on ice. The solution turned dark red, but did not produce any remarkable bubbling. This was allowed to stir for 40 minutes.
5 ml of ice cold acetone were added, and stirring continued for 10 more minutes on ice.
At this point, according to the protocol, the GSNO should have precipitated. Instead, the brilliant red color was still evenly dispersed in the acidic acetone mixture—it strongly resembled red koolaid. I tried adding 10-fold volumetric excess of acetone, and letting this sit overnight at -20C. I came in this morning, and it still looked like koolaid—no precipitation had occurred.
Does anyone know what went wrong? Any advice would be greatly appreciated.
Dear Damian,
Please see the attached protocol. you may find whats wrong.
friend
You may not know but there are two problems:
1 nitrous primaries thiols are less stable nitrosyl and lose contact with metals, acids, air, light and ...
So you recommend the use of neutral medium is an organic nitrosilante the tertbutilnitrito thus exist in the middle so their product oo tertbutanol which can be removed by vacuo, good luck
The original protocol (Hart, Tetrahedron letters 1985 pp. 2013-2016) used much more concentrated GSH: 1.53g GSH in 8mL H2O, with one equivalent HCl, and added 0.345g NaNO2. After 40 min in the cold 10 mL acetone are added, stirred for 10 min and the precipitate separated. The higher concentration of GSH facilitates the precipitation. More acetone may be needed. I recently synthesized another derivative of glutathione using 0.6M GSH and got it to precipitate with 3 volumes of acetone in the cold. Hope this helps
Good to know that my original procedure is still being improved upon.
From memory of 31 years ago the quantities are quite precise.
So need to take care with the weighings.
I was always surprised how stable GSNO was in direct contrast to its sodium salt or CYS-NO
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