Butyrate salts sold as dietary supplement
How to make Butyric Acid (Grignard Reaction, from bromopropane) - NileRed
How to make Butyric Acid (Oxidation of butanol) - NileRed
Butyric acid -> Microbial biosynthesis
https://en.wikipedia.org/wiki/Butyric_acid#Microbial_biosynthesis