pentamethylene

Pen`ta*meth"yl*ene, n. Etym: [Penta- + methylene.] (Chem.) Defn: A hypothetical hydrocarbon, C5H10, metameric with the amylenes, and the nucleus of a large number of derivatives; -- so named because regarded as composed of five methylene residues. Cf. Trimethylene, and Tetramethylene.

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