Acetate

Acetates (or ethanoate ), the salts and esters of acetic acid are called. The salts have the general structure CH 3 COO -M , abbreviated: AcO -M ( M is a monovalent cation ). The esters have the general structure CH3COOR ( sometimes abbreviated ACOR ), where R may be an aliphatic, aromatic or heterocyclic.

  • 2.1 Presentation
  • 2.2 occurrence

Salts

The salts are usually colorless, crystalline solids, which in their crystal lattices ( ionic lattices ) contain the acetate ion ( CH3COO -, AcO - ). This is the anion of acetic acid. Examples of salt-like acetates are sodium acetate ( CH3COONa ), potassium acetate ( CH3COOK ) or ammonium acetate ( CH3COONH4 ). With divalent cations to form salts such as calcium acetate ( ( CH3COO ) 2Ca ) or lead ( II ) acetate [( CH3COO ) 2Pb ].

Representation

The salts are obtained by neutralization of acetic acid with metal hydroxides or metal oxides:

Proof

In chemical analysis Acetate can be easily detected by grinds the sample with potassium hydrogen sulphate in a mortar. The proton (H ) of the hydrogen sulphate ion is transferred to the acetate, wherein the volatile acid is formed which can be easily identified by its typical smell:

Together with silver nitrate produces a flocculent, white precipitate of silver acetate, which, however, is easily soluble in dilute nitric acid again.

The proof can be done as fruity esters and identified the typical smell. (see section representation of the acetate ester )

Ester

Acetic acid esters ( CH3COOR ) are often called acetates. Ethyl acetate ( ethyl acetate) is the most famous of these esters. Esters with low molecular weight residues are usually liquid and are used as a solvent. Some of these esters, such as, for example, linalyl acetate, can be used as an odoriferous or aroma substance. A macromolecular acetic acid esters, for example, is of plastic cellulose acetate.

Representation

Acetates CH3COOR is obtained by esterification of acetic acid with alcohols (R- OH) or by reaction of acetyl chloride with alcohols.

Alternatively acetic anhydride may be reacted with alcohols to give esters of acetic acid.

Occurrence

Acetates in all biological organisms as metabolic products. In addition, there are some very rare minerals such as Hoganit, Paceit and Calclacit based on acetates. These are grouped both by the Strunzsche Mineral classification and the classification of minerals according to Dana in the group of organic minerals. Acetate as naturally occurring minerals are extremely rare, although acetic acid in nature is widespread. Until the recognition of Hoganits as a mineral (2002), Calclacit was the only known representative of this class of materials, being of anthropogenic origin. It was previously believed that Calclacit will remain the sole representative of the acetates and a purely natural formation of other acetates was considered very unlikely. By recognizing the Hoganits and Paceits by the IMA these are the first representatives of this class that have been created without anthropogenic influence.

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