Why is benzal chloride not written as benzal dichloride...? while we write benzotrichloride?

I need the appropriate reason.

1 Answer
Jan 9, 2018

Here is my guess for the reason.

Explanation:

These are both names that were used before systematic names were assigned.

Benzal chloride is prepared from benzaldehyde according to the reaction

www.prepchem.com

I would guess that, since the #"C"_6"H"_5"CH="# group is found in #bb("benzal")"dehyde"#, it was natural to call the compound #bb("benzal")color(white)(l)"chloride"#.

Benzotrichloride is made by chlorination of toluene.

www.prepchem.com

Presumably, the common group #"C"_6"H"_5"-"# group reminded the early chemists of benzene so they coined the name #bb("benzo")"trichloride"#.

The early names weren't very systematic and often the first person to discover a compound got to name it.