Alcohols and ethers
Naming alcohols and ethers: Practice exercises
How to name alcohols with -ol, diols and the hydroxy prefix, and ethers with alkoxy prefixes, with exercises, instant feedback and worked answers.
Alcohols carry an –OH group on a carbon with only single bonds and are named with the suffix -ol. Ethers have an oxygen between two carbon groups, C–O–C, and are named with an alkoxy prefix such as methoxy- or ethoxy-.
The rules you need
- The parent chain must contain the carbon that carries the OH; among such chains, take the longest.
- Number from the end nearer the OH. Its locant goes right before -ol and comes first in numbering, before double bonds and substituents: propan-2-ol.
- Replace the final e of the alkane with -ol: butan-1-ol. With two or three OH groups the e stays and the ending is -diol or -triol: ethane-1,2-diol, propane-1,2,3-triol.
- When a higher-ranking group is present, such as a ketone or a carboxylic acid, the OH becomes the prefix hydroxy-: the priority table is in the summary of the naming rules.
- Ethers: the larger carbon group is the parent (a ring, if one of the groups is a ring), and the other one, with the oxygen, is an alkoxy prefix: methoxyethane, methoxycyclohexane. Functional class names, such as ethyl methyl ether, list both groups in alphabetical order and add "ether".
Two names, read step by step
3-Methylbutan-1-ol
The longest chain that contains the carbon with the OH has four carbons. Numbering starts at the OH carbon, so the alcohol is at C1 and the methyl group at C3. From the other end the OH would get the locant 4, which the rules do not allow.
1-Methoxypropane
The oxygen joins a one-carbon group and a three-carbon group. The three-carbon chain is the parent, propane, and CH3–O– is the methoxy prefix on its C1. Its functional class name is methyl propyl ether.
Watch out for
- The OH gets the lowest locant even when a substituent then gets a higher one: 4-methylpentan-2-ol, not 2-methylpentan-4-ol.
- An OH on a benzene ring makes a phenol, which belongs to the benzene derivatives.
- An ether oxygen sits inside the drawn chain but not inside the parent name: ethoxyethane has four carbons.
Draw from the name: 18 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.
- propan-2-ol Beginner
- ethoxyethane Beginner
- butan-1-ol Beginner
- cyclohexanol Beginner
- methoxymethane Beginner
- ethane-1,2-diol Beginner
- 2-methylpropan-2-ol Intermediate
- propane-1,2,3-triol Intermediate
- pentan-3-ol Intermediate
- 2-methylbutan-2-ol Intermediate
- butane-1,4-diol Intermediate
- prop-2-en-1-ol Intermediate
- methoxycyclohexane Intermediate
- 2-methoxy-2-methylpropane Advanced
- 2-ethoxyethan-1-ol Advanced
- 1-methylcyclohexan-1-ol Advanced
- 3-methoxypropan-1-ol Advanced
- cyclohex-2-en-1-ol Advanced
Name the structure
18 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 Alcohols and ethers explains these names in more detail, with more worked examples and the most common mistakes.