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In organic chemistry, methylation is the transfer of methyl groups (–CH 3 ) from one molecule to another within a chemical reaction ( donor-acceptor principle ). The transfer of alkyl groups is generally called alkylation , the reagent alkylating agent.

The methylation reagents used are, for example, methanol , dimethyl sulfate , diazomethane or methyl halides, especially methyl iodide ; the use of methyl lithium is also possible. Diazomethane is only suitable for the methylation of acidic compounds such as phenols , carboxylic acids and enols . In the case of weaker acidic starting materials such as alcohols , the methylation can optionally be catalyzed by Lewis acids such as zinc chloride or by silica gel .

Under transmethylation is the transfer of a methyl group of methyl group donors on C-, O- or N-atoms of biomolecules under the catalytic action of methyltransferases . This happens, for example, in the synthesis of creatine , choline or betaine . The most important methyl group supplier is the essential amino acid methionine , which occurs in the form of adenosyl methionine (active methyl).

See also

Individual evidence

  1. ^ Beyer-Walter: Textbook of Organic Chemistry , 23rd Edition, S. Hirzel Verlag, Stuttgart 1998.
  2. ^ Albert Gossauer: Structure and reactivity of biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, p. 228, ISBN 978-3-906390-29-1 .
  3. Lexicon of Biology .