The two molecules below are the same, with just an alternative naming:
The former is preferred, as the benzyl substituent does not have sense to be used, if attached to the last carbon of the main chain.
As per the rule:
Longest carbon chain is to be considered.
Numbering of carbon should start from the side which has lowest set of locants i.e from right side, locants are 3,4 and from left side, locants are 2,3.
So answer is 2-3-dichloro pent-2-ene.
Who are you talking to? To non-chemists (in the US), just say i-oh-dyne.
But if you are talking with chemists, say i-oh-deen.
If you are talking to a mix of chemists and non-chemists, decide which you would like to be classified as.
Or, you could say "element 53".
Or we could just use German. In German they do not use the suffix for halogens at all so that "iodine" is just "Jod". Now all we have to remember is that you don't pronounce the long "i", instead using the usual "j"/"y" consonant sound.
The most important simplified criteria for the numbering in such cases are:
lower locants for the principal characteristic groups, which are expressed as a suffix or implied by the name of the functional parent compound
lower locants for prefixes
lower locants for substituents cited first as a prefix in the name
The corresponding actual wording in the ...
When choosing which name to use when the only difference is the numbering, we choose the combination that gives the lowest possible numbers, 2 and 4 in this case.
So the name will be 4-bromo-2-methoxyphenol. The substituents are given in alphabetical order.