monomethylate
/ˌmɒnə(ʊ)ˈmɛθɪleɪt/Chemistry
verb
[with object] To convert into a monomethyl derivative; to introduce a methyl group into (a compound) as a substituent.
Origin
1980s; earliest use found in Proceedings of the National Academy of Sciences of the United States of America. From monomethyl + -ate; compare methylate.