I need some help with Ether's nomenclature. What are the IUPAC names for following? I'm confused with different names.
The IUPAC accepts two different names for ethers: (a) a substitutive name; (b) a functional class name.
(a) Substitutive names
The ether is named as an alkoxyalkane, with the smaller group being the "alkoxy" part of the name.
This is the preferred IUPAC name (PIN).
In this system, your first compound is butoxybenzene.
Your second compound has a benzene ring with a methyl group that is itself substituted with a methoxy group — a methoxymethyl group.
Your second compound is (methoxymethyl)benzene.
The parentheses remove any ambiguity — they show that the methoxy group is on the methyl and not on the benzene ring.
(b) Functional class names
You name the compound with the class name ether as a separate word: e.g. alkyl alkyl ether or dialkyl ether.
This is probably the most commonly used system.
You name the alkyl groups on either side of the O atom and add the word "ether".
You list the alkyl groups in alphabetical order, and the names of your compounds become butyl phenyl ether and benzyl methyl ether.