Orthoester

Ortho ester (more precisely, orthocarboxylic acid ester ) of the general formula R -C ( OR ') 3, triple esters of non-existent in the free form ortho- carboxylic acids [R- C (OH) 3], and addition products of carboxylic acids and water ( hydrates). Ortho carboxylic acids follow the Erlenmeyer rule; the equilibria of the addition of water are clearly on the side of the carboxylic acids.

Examples of ortho esters are CH3C ( OCH2CH3 ) 3, trimethyl orthoformate, HC ( OCH3) 3, triethyl orthoformate, HC ( OCH2CH3 ) 3, triethyl or Daphnetoxin (ortho esters of benzoic acid ). In tetrodotoxin the structural element of a Orthocarbonsäuredialkylesters as the anion is present.

Representation

The preparation of ortho esters can be carried out by the reaction of nitriles with an alcohol under acid catalysis:

The orthoformic acid ester can be accessed by a Williamson ether synthesis from chloroform and sodium alkoxides of the corresponding alcohols.

In weakly acidic aqueous solutions resulting from an ortho ester, a carboxylic acid ester and an alcohol:

Use and characteristics

Ortho esters are used in the organic synthesis as protecting groups for carboxylic acids. The reaction of ketones with orthoesters provides ketals and carboxylic acid esters. They are also suitable for the removal of water, for example from reaction mixtures.

Inorganic acids can form orthoester, the ortho acid ester.

Ortho esters are chemically related to carboxylic acid esters, ethers and acetals.