Carboxylic acids and their derivatives

chapter 8 george facer

HideShow resource information
Preview of Carboxylic acids and their derivatives

First 423 words of the document:

Further Organic Chemistry ­ Revision.
Carboxylic Acids.
Carboxylic acids contain the group ­COOH. This is called the carboxyl group, because in consists of
the carbonyl group and the hydroxyl group.
There is hydrogen bonding between the first few carboxylic acids, but as the carbon chains grow, the
hydrogen bonding is inhibited by the zigzag chains. All carboxylic acids have strong smells.
Preparation.
Oxidation of a primary alcohol, or an aldehyde, by heating acidified potassium dichromate
under reflux.
Hydrolysis of an ester. (see ester reactions).
Hydrolysis of a nitrile. A nitrile is a compound that contains the CN group.When heated under
reflux with a dilute acid, the nitrile is hydrolysed to a carboxylic acid and an ammonium salt.
When heated under reflux with aqueous alkali, the salt of the carboxylic acid is formed, and
addition of a strong acid protonates it and the carboxylic acid is formed.
The iodoform reaction of a methyl ketone or a secondary alcohol, on addition of a solutions
of iodine in aqueous sodium hydroxide to a methyl ketone, the salt of the acid with one less
carbon is formed, and then the acid can be formed by adding excess strong acid.
Reactions.
with water , carboxylic acids react reversibly with water.
with bases, carboxylic acids form salts with bases. All carboxylic acids are weak acids
with carbonates and hydrogencarbonates, carboxylic acids produce carbon dioxide when
added to a carbonate or a hydrogencarbonate
esterification, carboxylic acids react with alcohols in the prescence of concentrated sulphuric
acid, which acts as a catalyst, in a reversible reaction to form esters.
Reduction, carboxylic acids are reduced by lithium tetrahydridoaluminate, dissolve in dry
ether, to a primary alcohol.
Formation of acid chloride, a carboxylic acid added to solid phosphorus pentachloride forms
the acid chloride.
Formation of a halogenoacid, if chlorine is bubbled into a boiling carboxylic acid in the
presence of sunlight, or U V, chlorine replaces one of the hydrogen atoms on the carbon
chain. This is an example of free radical substitution.
Esters .
Have the structural formula of RCOOR', where R will be a hydrogen atom or an organic residue, such
as methyl. R' must be a residue of an alcohol with a carbon atom attached to the oxygen of the ester.
They are named by the alcohol residue, followed by the name of the carboxylate group:

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Most esters are liquid at room temperature. They are insoluble in water, as they cannot form
hydrogen bonds, as the oxygens are sterically hindered.
Preparation.
Warm an alcohol with a carboxylic acid under reflux, with a few drops of sulphuric acid.
The alcohol can be reacted with an acid chloride at room temperature, and this gives a higher
yield, as the reaction is not reversible.
Reactions.…read more

Page 3

Preview of page 3

Here's a taster:

Preparation.
They are prepared from carboxylic acids. The ­OH group is replaced by a chlorine atom. The
reagents which can be used are phosphorus pentachloride, phosphorus trichloride or thionyl
chloride.
Reactions.
With water, ethanoyl chloride reacts vigorously with water, forming ethanoic clouds and
clouds of hydrogen chloride gas. As a result of this, when using ethanoyl chloride as a
reactant, all reagents and glassware must be dry.…read more

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »