This combined functional group is called carboxyl.
General Formula
R–C=O
o
R – COOH
OH
The bond between the oxygen atom and hydrogen of the
carboxyl group is extremely polar, this allows the formation of
hydrogen bridges within the acid molecules and also with the
water and acid molecules.
IUPAC system. The carboxylic acids are named taking as root name
the name of the hydrocarbon with the same number of carbon, of the
longest continuous chain that the carboxyl group has, adding the oic
and followed by the word acid.
Example:
CH3CH2CH2COOH
Butanoic acid
CH3CH2CH2CH2CH2COOH
Hexanoic acid
To indicate the position of its substituents or of the functional group
number are used and they added in front on the root name. Carbon
of the carboxyl group is always number 1.
CH 3CH2CHCH 2CHCH2CH2COOH
Cl
OH
acid 6-chloro-4-hydroxy octanoic
Common System
Many carboxylic acids when already know by common names
before the IUPAC was created, for this reason many of them are
know today by their common name, the most important are in the
following table.
Formula
Common Name
IUPAC Name
HCOOH
Ac. Formic
Ac. Methanoic
CH3COOH
Ac. Acetic
Ac. Ethanoic
CH3CH2COOH
Ac. Propionic
Ac. propanoic
CH3(CH2)2COOH
Ac. Butyric
Ac. butanoic
CH3(CH2)3COOH
Ac. Valeric
Ac. pentanoic
CH3(CH2)8COOH
Ac. Caproic
Ac. decanoic
CH3(CH2)10COOH
Ac. Laruic
Ac. dodecanoic
CH3(CH2)14COOH
Ac. Palmitic
Ac. hexadecanoic
CH3(CH2)16COOH
Ac. Stearic
Ac. octadecanoic
Monocarboxylic acids with 5 carbon atoms are soluble in water,
while dicarboxylic are soluble in water even when the have 8 carbon
atoms.
Benzoic acid, is the simplest aromatic acid and it in not very soluble
in water.
Boiling points in acids are high compared to the other organic
families that we have studied to date. The boiling point of the
simplest acid, formic acid is of 100.5 C.
Acids with 1 to 9 carbon atoms melt at room temperature, the ones
with higher molecular weight and dicarboxylic acids are solid at
room temperature.
Formic and acetic acid have penetrating and strong smells.
Formation of Salts
R – COOH + NaOH

R – COONa + H2O
carboxylic of sodium
Formation of Esters
R – COOH + R´- OH
 R - C – O – R´ + H2O
O
R – COOH + LiAlH4  R – CH2 – OH + LiOH
Al(OH)3
Used as conservatives and flavoring for many foods like butter,
yogurt, sour cream, salsas, dressings, cheese, bread and mayonnaise,
etc.
Vinegar is a solution of acetic acid.
Medicine for the treatment of callus and moles (salicylic acid).
Production of soaps and shampoos
Fabrication of paints (drying oils)
Textiles and plastics (acetylcellulose)