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20.9 Disubstituted Benzene Derivatives

20.9 Disubstituted Benzene Derivatives

20.9.1 Ortho, Meta, Para

When two groups are attached to a benzene ring, there is a common way to name them using the prefixes ortho, meta, and para. The way to remember the order of the prefixes is to remember “ROMP”. Let’s look at a generic R group on a phenyl ring. The carbon atom attached to the R group is called the ipso carbon atom. The carbon atom next door to the R group, the 2nd carbon atom, is the ortho carbon atom. The 3rd carbon atom is meta, and the 4th carbon atom is para. This spells “ROMP” around the ring.

ortho, meta, para positions
ortho, meta, para chlorophenol

There are some common disubstituted benzenes that you should know, toluic acid, cresol, and xylene.

p-toluic acid, meta-cresol, ortho-xylene

20.9.2 Benzene groups as substituents

Benzene rings groups can be named as substituents. A benzene ring attachment is called a phenyl group. A group with a CH2 followed by a benzene is called a benzyl group.

phenyl chloride, benzyl chloride

8. Name the following compounds using the common prefix (ortho, meta, para) when appropriate.

a)
Problem 8a, disubstituted benzene derivatives
b)
Problem 8b, disubstituted benzene derivatives
c)
Problem 8c, disubstituted benzene derivatives
d)
Problem 8d, disubstituted benzene derivatives
e)
Problem 8e, disubstituted benzene derivatives
f)
Problem 8f, disubstituted benzene derivatives
g)
Problem 8g, disubstituted benzene derivatives
h)
Problem 8h, disubstituted benzene derivatives
i)
Problem 8i, disubstituted benzene derivatives