The prefix "ortho-" means straight or right; "meta-" means beyond or after; "para-" means beside or along. How, then, did ortho-, meta- and para- come to refer to the carbon positions one, two, and three positions away from a reference point on a benzene?

If we have two groups on a benzene ring immediately beside one another, we do not denote the positions by para-, which would seem logical given its meaning, but instead ortho-. For instance, a benzene ring with two hydroxyl (-OH) groups on immediate positions of a benzene ring can be called para-hydroxybenzene (with the common name "quinone"). What is the etymological history that led to the rather counterintuitive use of these prefixes in organic chemistry?


Wilhelm Körner between 1866-1874 was the first to use it to differentiate isomers of benzene rings. Since the Greek suffixes are fairly vague he chose them arbitrary. Its interesting he used orth- for 1,4 isomer, meta- for the 1,2 isomer , and pera- for the 1,3 isomer. While later chemists used orth- for 1,2 isomer, meta- for the 1,3 isomer , and pera- for the 1,4 isomer. Then in 1879 the Chemical Society of London officially adopted the backwards notation.

So yea its a arbitrary and backwards system. I got all my info from the one link below.

The Origins of the Ortho-, Meta-, and Para- Nomenclature


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.