[11C]Methanol production by a fast and mild aqueous-phase reduction of [11C]formic acid with samarium diiodide
✍ Scribed by Dirk Roeda; Frédéric Dollé
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- French
- Weight
- 156 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0022-2135
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The reduction of [^11^C]carbon dioxide to [^11^C]methanol with lithium aluminium hydride (LiAlH~4~) and subsequent conversion into [^11^C]methyl iodide is a standard way of producing the latter precursor for radiolabelling. However, it suffers from appreciable losses by incomplete reduction giving [^11^C]formate. We show that samarium diiodide (SmI~2~) can be used to improve the yield of [^11^C]methanol by its ability to efficiently reduce [^11^C]formate to [^11^C]methanol. This can be done either by making [^11^C]formate intentionally and treating it with SmI~2~ or by treating the LiAlH~4~‐reduced [^11^C]CO~2~ with SmI~2~. In the latter approach, sodium thiosulphate has a similar effect as SmI~2~. Hydriodic acid was also shown to exert some reducing action on [^11^C]formate too. [^11^C]Carbonate is reduced to a small extent by SmI~2~ under the mild conditions employed. In contrast to the very easy [^11^C]formate reduction, SmI~2~ had little effect on [^11^C]acetate and practically no [^11^C]ethanol could be produced. Copyright © 2006 John Wiley & Sons, Ltd.