Organic acids . They are oxygenates derived from hydrocarbons that are formed by substituting two hydrogens on a primary carbon for an oxygen that joins the carbon through a double bond, and the third hydrogen with a group (OH) that is joined by a single bond, the group formed by this substitution, which as we have said is always located at one end of the chain and is called carboxyl.
Summary
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- 1 Classification
- 2 Nomenclature
- 3 Physical and chemical properties
- 4 Obtaining
- 5 Some applications
- 6 Sources
Classification
According to the number of carboxyl groups, organic acids are classified into:
- Monocarboxylic, have a single carboxylic group.
- Dicarboxylic, have two carboxylic groups.
- Tricarboxylic, have more than two carboxylic groups.
Nomenclature
1.- According to the IUPAC, the name of the carboxylic acids is derived from the corresponding hydrocarbon with “oico” termination, considering carbon 1 to carbon of the functional group.
Example:
CH 3 -COOH ethanic acid
2.- If the molecule contains more than two carboxylic groups, it is preceded by the ending “oico”, the prefix di, tri, etc.
Example:
HOOC-CH 2 -COOH propanedioic acid
3.- For aromatic acids, benzoic acid and [naphthoic acid]] are taken as the base .
4.- When there are substituents or multiple bonds, the chain is numbered giving # 1 to the carbon of the carboxyl.
5.-When there are substituents, Greek letters are used to designate the carbons, starting from the carbon closest to the carboxyl.
Physical and chemical properties
- The first three terms in the fatty acid series are colorless liquids with a pungent and unpleasant odor.
- They have high boiling points and rise as the number of carbon atoms increases.
- The first three are insoluble in waterand this solubility decreases, as the number of carbon atoms increases . From octanoic acid they are insoluble in water.
- They are liquid up to decanoic acid.
- Organic acids are weak acids that react with alcohols toform esters .
Obtaining
- Organic acids are compounds that are formed by oxidizing an aldehyde. This occurs because the hydrogen in the aldehydefunctional group (-CHO) is replaced by the hydroxyl group (-OH).
- By moderately oxidizing a primary alcohol (in the presence of a catalyst like KMnO4) which will produce its respective aldehyde and in turn by continuing to oxidize it will produce the respective carboxylic acid.
Some applications
- The formic acidis used in antiseptic and antirheumatic textile, leather processing, MANUFACTURING insecticides, refrigerants, solvents, mirrors. It is a corrosive liquid, miscible in water , alcohol and ether . It is the strongest acid in the series. The ants red have formic acid.
- The ethanoic acidor acetic acid is used in the preparation of acetates, Cleaning, preparation of vinegar , manufacture of plastics , dyes and insecticides .
- The benzoic acidis used in dyes, and food preservation.
- The myristic acid, lauric acid , palmitic acid , stearic acid and oleic acid are used in the preparation of soaps .
- The citric acidused in the preparation of soft drinks and drug development.
