Question

What is the name of a benzene ring that has a `CO_2C_2H_5^-` group attached and an `OH^-` group attached *para* to each other?

Answer 1

4-hydroxyphenyl propanoate

Explanation:

In the question the name of the benzene ring is wanted.
Though the question is not very clear to me, I am trying to explain a probable answer with my little knowledge.

By the question the group `CH_3CH_2-CO-O-` is attached with a benzene ring in which a `-OH` group is attached in para i.e. 4-position with respect to the first one

Since the group `CH_3CH_2-CO-O-` is derived from propanoic acid `CH_3CH_2-CO-O-H` and the given compound is formed due to replacement of H atom of `-OH` group of the acid by a para or 4- hdroxyphenyl group ,the compound belongs to ester class and as per IUPAC rule the ester group is to be given priority .here.

So it is an ester of propanoic acid (as it is a carboxylic acid with 3-C atoms in its chain). The naming of an ester is equivalent to naming of a salt of an acid where name of the group which replaces H atom of `-COOH` group comes first and then keeping a gap the rest part of the name derived from parent acid (here propanoic acid) with -oate suffix is added to it. (propan + oate = propanoate)

So the two word name is written as
4-hydroxyphenyl propanoate