Isoprene, also known as 2-methyl-1,3-butadiene, is a five-carbon hydrocarbon that exists in nature at trace levels. It is a colorless, volatile liquid with the chemical formula C5H8.

Tetrahydrofuran (THF), also known as oxolane, is a cyclic ether with the chemical formula C4H8O. It has a wide application in the chemical industry.

Crotonaldehyde [4170-30-3], also known as 2-butenal, is a colorless liquid with a pungent odor and strong lacrimatory properties. It has a chemical formula of CH3CH=CHCHO, and it exists as two stereoisomers: cis-crotonaldehyde [15798-64-8] and trans-crotonaldehyde [123-73-9].

Trimethylamine is an organic compound with the formula N(CH3)3. It is a colorless gas or compressed liquid with a strong fishy odor, at low concentrations. At higher concentrations, the odor becomes more ammonia-like.

Dimethylamine is an organic compound with the formula (CH₃)₂NH. It is a colorless, flammable gas with an ammonia-like odor, although at low concentrations it can smell like fish, and its odor is more potent than methylamine and less than trimethylamine. Dimethylamine is commonly encountered commercially as a solution in water at concentrations up to around 40%.

Methylamine is the simplest primary amine, with the formula CH3NH2. It's a colorless gas that's derived from ammonia, with one hydrogen atom replaced by a methyl group. It was first synthesized in 1849 by Wurtz alongside dimethylamine and trimethylamine.

Choline [62-49-7], also known as trimethyl(2-hydroxyethyl)ammonium hydroxide, is a quaternary ammonium compound with the molecular formula C₅H₁₅O₂N. It was first isolated from pig bile in 1849 by Stecker and is subsequently found in brain tissue.