Meta (chemistry)

Positions on an aromatic ring relative to the R group

In chemistry, meta is a prefix, used for systematic names in IUPAC nomenclature. It has several meanings.

• In organic chemistry, meta indicates the positions of substituents in aromatic cyclic compounds. The substituents have the 1,3-positions, for example in resorcinol.
• Meta may also denote the dehydrated form of an acid, salt or organic derivative in a series. For example:
  • metabisulfite:

  2 bisulfite (HSO−3) → 1 metabisulfite (S₂O2−5) + H₂O

  • metaphosphoric acid:

  3 orthophosphoric acid (H₃PO₄) → 1 trimetaphosphoric acid (H₃P₃O₉) + 3 H₂O

  • Meta-antimonic acid, the dehydrated form of antimonic acid (H₃SbO₄), is HSbO₃.

See also

• Arene substitution patterns