✦ LIBER ✦

Synthesis of caffeine-2−14C

✍ Scribed by Erich Heftmann

Publisher: John Wiley and Sons
Year: 1971
Tongue: French
Weight: 116 KB
Volume: 7
Category: Article
ISSN: 0022-2135
DOI: 10.1002/jlcr.2590070412

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✦ Synopsis

X~nthine-2-'~C (1) was converted to cafleine-2-11C (2) by methylation with dimethyl sdjate.

INTRODUCTION.

In connection with a research project on the metabolism of caffeine (2) by micro-organisms (l) radioactive caffeine was needed. The only commercially available 14C-labelled caffeine is caffeine-I-methyl-14C *. However, ring labelled caffeine would be preferable for metabolic studies, because the N-methyl group may be lost early in the course of caffeine degradation. It was decided, therefore, to prepare caffeine-2-14C by methylation of the commercially available xanthine-2-14C ** (1). The method chosen for this synthesis is an adaptation of the procedure described by Bredereck et a/. (2).

EXPERIMENTAL

Xanthine-2-14C, having a specific activity of 50 pC per 158 pg, was dissolved in 0.25 N sodium hydroxide to give a solution with 1 pC/ml. In a fume hood a 100-ml beaker, containing 25 ml of this solution, 15 ml of water, and 2 ml of dimethyl sulfate ***, was mounted on a magnetic stirrer. The electrodes of a pH meter were introduced into the mixture and 5 N sodium hydroxide was added dropwise with continuous stirring at such a rate that the * Tracerlab, Irvine, California. Reference to a company or product name does not imply approval or recommendation of the product by the U. S. Department of Agriculture to the exclusion of others that may be suitable.

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