Benzene derivatives
Naming benzene derivatives: Practice exercises
How to name benzene derivatives: ring numbering, ortho, meta and para, and parents such as phenol, aniline and benzoic acid, with exercises and worked answers.
Benzene derivatives are named either as substituted benzenes or from a parent with a retained name, such as phenol (C6H5OH), aniline (C6H5NH2), benzoic acid and benzaldehyde.
The rules you need
- One substituent needs no locant, because every position of the ring is the same: ethylbenzene, nitrobenzene.
- Two or more substituents: number the ring to give them the lowest locants; if two directions tie, the prefix cited first in alphabetical order gets the lower number: 1-bromo-3-chlorobenzene.
- Two substituents can also be described as ortho (1,2), meta (1,3) and para (1,4), written o-, m- and p- in many common names.
- With a parent such as phenol, aniline or benzoic acid, the carbon that carries its group is C1, and the other substituents are numbered from it: 4-methylphenol.
- Methylbenzene is also called toluene, its preferred IUPAC name. Its derivatives are named as benzenes: 1-ethyl-4-methylbenzene.
Two names, read step by step
1,2-Dichlorobenzene
Two chlorines on neighboring ring carbons. Starting at one of them and counting toward the other gives the locants 1 and 2, the ortho position. Counting the other way around would give 1 and 6.
3-Methylphenol
Phenol is the parent, so the carbon with the OH is C1. Counting around the ring the shorter way, the methyl group is on C3, meta to the OH.
Watch out for
- In a phenol, aniline or benzoic acid, never start numbering at another substituent: C1 carries the OH, NH2 or COOH.
- The alternating double bonds of benzene can be drawn either way round; both drawings are the same molecule.
- A CH2 between the ring and a group changes the compound: phenylmethanol is not a phenol.
Draw from the name: 19 exercises
Each name opens its exercise. Draw the structure and check it: any correct drawing is accepted, and hints and a worked answer help when you are stuck.
- methylbenzene Beginner
- 1,4-dimethylbenzene Beginner
- ethylbenzene Beginner
- phenol Beginner
- nitrobenzene Beginner
- benzoic acid Beginner
- benzaldehyde Beginner
- 1-bromo-3-chlorobenzene Intermediate
- 4-methylphenol Intermediate
- 4-chloroaniline Intermediate
- 2-nitrophenol Intermediate
- ethenylbenzene Intermediate
- 1-ethyl-4-methylbenzene Intermediate
- (propan-2-yl)benzene Intermediate
- 4-nitrobenzoic acid Advanced
- 1,3,5-trimethylbenzene Advanced
- 1-chloro-2-nitrobenzene Advanced
- 4-hydroxybenzoic acid Advanced
- methyl benzoate Advanced
Name the structure
19 structures of this family to name, each with four names to choose from and an explanation of every wrong choice.
Printable worksheet
For practice on paper: names to draw and structures to name, with an answer key to check your work.
The full guide
The guide Benzene derivatives explains these names in more detail, with more worked examples and the most common mistakes.