Final answer:
The IUPAC name for methanol is derived from methane by replacing the ending -e with -ol. Propyl methyl ether is an ether, not an alcohol, and is named based on its alkyl groups. 2-Methoxybutanal is a butanal with a methoxy substituent on the second carbon.
Step-by-step explanation:
The IUPAC naming system for alcohols involves using the name of the hydrocarbon from which the alcohol is derived and replacing the final -e with -ol. For instance, methanol is named based on methane, and ethanol is based on ethane. When naming ethers, the alkyl groups on either side of the oxygen are named in alphabetical order followed by the word ether. With larger alcohols or more complex molecules, the OH group's position is indicated by a number in the compound's name.
Let's apply this system to the given examples:
- For methanol, you maintain the base name of methane and replace -e with -ol, as there is only one carbon atom and the OH group is attached to it.
- When encountering a compound like propyl methyl ether (CH₃CH₂CH₂OCH₃), it is named based on the two alkyl groups on either side of the oxygen atom, which are propyl and methyl, and it is an ether, not an alcohol.
- The compound OCH₃CH₃CH₂CHO would be named as 2-methoxybutanal because it contains an aldehyde group (CHO) on a butane chain and a methoxy group as a substituent on the second carbon.