Propane

google

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mid 19th century: from propionic acid + -ane2.

wiktionary

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prop- +‎  -ane, modelled on German Propan. 

etymonline

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propane (n.)

"colorless gas occurring in petroleum," 1866, with chemical suffix -ane + prop(ionic acid) (1850), from French propionique (1847), from Greek pro "forward" (see pro-) + pion "fat" (see fat (adj.)), which was so named in reference to its being first in order of the fatty acids.