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10.4 Carboxylic Acids and Esters

10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

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Page 1: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

10.4 Carboxylic Acids and Esters

Page 2: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Carboxylic Acids

• These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group (an OH group like in alcohols)

• The general structural formula is: O IIR - C - OH

• this can be written: R-COOH

Page 3: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Carboxylic Acids

• They are weak acids due to their slight ionization in water to release a hydrogen ion.

O O

II IIR - C - OH(aq) R - C - O-

(aq) + H+(aq)

Page 4: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Naming Carboxylic Acids

• In order to name these compounds: • First, identify the longest parent chain with

the carboxyl group. • Then drop the -e ending and add the

ending -oic and the word acid.

Page 5: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

The first three Carboxylic Acids

• methanoic acid ethanoic acid propanoic acid

O O O II II II H - C - OH CH3 - C - OH CH3 – CH2 - C - OH

Page 6: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Polycarboxylic Acids

• You do not have to memorize these names and condensed formulas, all you must recognize is that these are carboxylic acids.

Page 7: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties of Carboxylic Acids

• Like other organic derivatives many of these compounds have common names, derived from the origin of the acid.

• Carboxylic acids are widely distributed in nature.

• They are present in all cells and are a component of fats.

• Fatty acids are carboxylic acids in fact.

Page 8: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties of Carboxylic Acids

• The common name for methanoic acid is formic acid since it is found in ants (the Latin for ant is formica).

• For ethanoic acid the common name is acetic acid, from acetum (Latin for sour wine, as in vinegar).

Page 9: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties of Carboxylic Acids

• Short chain carboxylic acids are volatile liquids with sharp, unpleasant odours such as sweaty feet, vomit and rancid butter.

• Tracker dogs follow the trail of carboxylic acid smell from the body odour of the subject.

• The polar nature of the carboxyl group allows these organic acids to be misable with water.

• Larger chain organic acids are waxy solids that are insoluble in water, but will dissolve in solvents such as ethanol or propanone.

Page 10: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Esters

• A compound called an ester is composed of an alcohol and a carboxylic acid.

• The process to create an ester is simply called esterfication.

Page 11: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Formation of an Ester

• Since water is eliminated in the process of this reaction, it may be called a condensation reaction.

Page 12: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Naming Esters

• We name esters by identifying the alcohol chain, dropping the -ol, and adding –yl.

• Then we name the acid by dropping the -ic acid and adding -ate.

Page 13: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group
Page 14: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group
Page 15: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties and Occurrence of Esters

• Lower molecular weight esters are colourless, volatile liquids that are soluble in water.

• Higher molecular weight examples are colourless, waxy solids that are insoluble in water.

• All esters have characteristic strong “fruity” smells and are soluble in non-polar organic solvents.

• Esters are themselves good organic solvents.

Page 16: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties and Occurrence of Esters

• Esters break down into their respective organic acid and alcohol from which they are formed.

• This process is called hydrolysis. • When sodium hydroxide is added to an

ester, for example to ethyl ethanoate, a salt, sodium ethanoate is formed along with ethanol.

Page 17: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties and Occurrence of Esters

• The reaction is shown below:

• Hydrolysis of an ester with an alkaline solution like sodium hydroxide is known as saponification.

• This reaction is used in the preparation of soaps from fats, which are esters of glycerol and fatty acids.

Page 18: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Properties and Occurrence of Esters

• Esters are found widely in nature as the flavour and odors of flowers, fruits and nuts.

• They are manufactured as artificial perfumes or scents and artificial food flavours that are added in many edible items like ice creams, soft drinks, sweets, etc.

• In industry, esters are used as solvents for making cellulose, fats, paints and varnishes and in the pharmaceutical industries. 

• Esters are also used as softeners in plastic and molding industries.

Page 19: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group
Page 20: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group
Page 21: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

butan-1-ol

hexan-1-ol

octan-1-ol

Page 22: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

2-methylpropan-1-ol

butan-2-ol

Page 23: 10.4 Carboxylic Acids and Esters Carboxylic Acids These are compounds with a carboxyl group, which consists of a carbonyl group and a hydroxyl group

Alcohol Acid Ester produced Smell

Methanol Butanoic acid Methyl butanoate Pineapple

Methanol Benzoic acid Methyl benzoate Marzipan

Methanol Salicylic acid Methyl salicylate Wintergreen

Ethanol Methanoic acid Ethyl methanoate Raspberry/rum

Ethanol Ethanoic acid Ethyl ethanoate Pear drops/nail-varnish remover

Ethanol Butanoic acid Ethyl butanoate Pineapple

Propan-1-ol Ethanoic acid Propyl ethanoate Pear

Pentan-1-ol Ethanoic acid Pentyl ethanoate Banana

Pentan-1-ol Butanoic acid Pentyl butanoate Apricot/pear

Pentan-1-ol Pentanoic acid Pentyl pentanoate (Pine)apple

3-methylbutan-1-ol (isoamyl alcohol)

Ethanoic acid 3-methylbutyl ethanoate Banana/bee alarm pheromone

Octan-1-ol Ethanoic acid Octyl ethanoate Orange

Phenylmethanol (benzyl alcohol)

Ethanoic acid Benzyl ethanoate Peach