ميتا- (كيمياء)

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 (S
  2O2−
  5) + H
  2O

  • metaphosphoric acid:

  3 orthophosphoric acid (H
  3PO
  4) → 1 trimetaphosphoric acid (H
  3P
  3O
  9) + 3 H
  2O

  • Meta-antimonic acid, the dehydrated form of antimonic acid (H
    3SbO
    4), is HSbO
    3.

 See also

• Arene substitution patterns