الكيمياء العضوية العملي

IDENTIFICATION OF CARBOXYLIC ACID
Carboxylic acids are organic compounds that have, a carboxyl group (-COOH) attached, to
hydrogen (HCOOH), to an alkyl group (RCOOH),or to an aryl group (ArCOOH):
They may by mono carboxylated such as formic acid and, acetic, acid, multi carboxylated
such as oxalic acid and succinic acid, hydroxylated such as lactic acid and citric acid, of they
may be aromatic such as benzoic acid and salicylic acid.
Their special properties are attributed to the proton of the carboxyl group, Mono
carboxylic acids c.re weak acids except formic acid, which is the strongest. The tendency of
the alkyl group to release electrons weakens the acid; thus formic acid is the strongest. On
the other hand presence of e1ectron with drawing groups (such as halogens) especially on
the alpha carbon increases the acidity.
Carboxylic acids that have long, straight-chain hydrocarbon group (with 12 or more C atoms)
are commonly classified as fatty acids, and several are biological importance.
Fatty acids occur in animal or vegetable tissue and nearly always have an even number of C
atoms. Those that have only single bonds between C atoms are saturated fatty acids, while
those with one or more C=C double bond are unsaturated fatty acid. The general formula of
saturated fatty acid is:
CnH2n+1COOH
Stearic acid is saturated fatty acids with 17 C atoms in the hydrocarbon group, R, so general formula is:
C17H2(17) +1COOH = C17H35COOH