ALDEHYDES, KETONESAND Carboxylic Acids

 Define ALDEHYDES

are organic compounds which contain aldehydic carbonyl (-CHO) as a functional group.

The general formula of aldehyde is R-CHO or Ar-CHO where ,

R= Alkyl group

Ar=Aryl group or hydrogen

Define ketones

Ketones are organic compounds which contain carbonly (C=O) as a functional group.

The general formula of ketones

Where R= Alkyl group or replace AR=Ary

  O

  ||

R-C-R

Nomenclature of Aldehydes

a) Common names of aldehyde

An aldehyde has acommon name for the simple aldehydes which are derived from

corresponding common names of Carboxylic acids by changing-ic acid into aldehyde

For examples

       O

      ||

a)H-C-H

Formaldehyde form fotmic acid

            O

           ||

b)CH3-C-H

Acetaldehyde form acetic acid

                             O

                             ||

c) CH3-CH2-CH2-C-H

Butyraldehyde from butyric acid

                     O

                    ||

d)CH3-CH2-C-H

Propionaldehye form propionic acid

Iupac nomenclatures of aldehyde

The iupac names of Aldehydes are derived from the names of alkanes having the same

number of carbaon atoms by changing last"-e-"into"-al"

Rules of system

1. Find the longest chain containing the CHO group

2. Number the chain or ring to put the CHO group at C1, but omit this number from the

same.

3. The branched groups are indicated by using number

4. Change the"-e" ending of the parent alkane to the suffix

Nomenclature of ketones

a) Common names of ketones

i.common names of ketones are formed the names of the two groups attached to the

carbonyl group, followed by the word ketone

ii.the alkyl groups are listed in alphabetical order followed by the word ketone

iii.use a perfix if both alkyl groups are the same

Example

Give common name for each of the following ketones

1 Methyl group Ethyl group

    ↓  O            ↓

       ||

CH3-C-CH2CH3

Iupac nomenclatures of ketones

The iupac names of ketones are derived from the names of alkanes having the same

number

i. Find the longest chain containing the group- C=O

ii.Number the carbon chain to give the carbonyl carbon the lower number.

iii. Use a number to indicate the position of the branched groups.

iv. Indicate the position of carbonyl carbon using a number

v. Change the -e ending of the parent alkane to the suffix-one

Classification of Carboxylic acids

1 Mono-carboxylic acid

2 Di-carboxylic acid

3 Tri-carboxylic acid

Mono-carboxylic acidare carboxylic acid containing one carboxyl group in their molecules.

For Example

a) HCOOH → formic acid

b) CH3COOH → acetic acid

Di-carboxylic acidare carboxylic acid containing two carboxyl group in their molecules

For example

a) HOOC-COOH → Oxalic acid

b) HOOC-CH2-COOH→ malonic acid

Tri-carboxylic acidare carboxylic acid containing three Carboxyl group in their molecules

For example

a) C6H8O7 → Citric acid

Preparation of aldehyde and ketones

1 Oxidation of primary alcohols

2 Oxidation of secondary alcohols

Reaction of aldehydes and ketones

1.Oxidation of aldehyde and ketones

2.Reduction of aldehyde and ketones

Define Carboxylic acids

Carboxylic acids are organic compounds which contain Carboxyl(-COOH) as a functional

group

The general formula of Carboxylic acids is: R-COOH or Ar-CHO

Where R=Alkyl group or hydrogen

Ar=Aryl group.

The simplest of carboxylic acids is HCOOH where R=H(hydrogen)

The word Carboxyl (for aCOOH group) is derived from carbonyl (C=O)+hydrogen (OH)

Carboxylic acid common name Latin & English

a)HCOOH formic acid formica ant

b) CH3COOH acetic acid acetum vinegar

c) CH3CH2COOH propionic acid propionate first salt

d)CH3CH2CH2OOH butyric acid butyrum butter

IUPAC namenclature of Carboxylic acids

The iupac names of Carboxylic acids are derived from the names of alkanes having the

same number of carbaon atoms by changing the last-e-with the suffix-oic acid:

i. Find the longest chain containing the (-COOH) group.

ii.Number the chain or ring to put (-COOH) group at C1, but omit this number from the

names.

iii.the branched groups are indicated by using numbers.

iv change the -e- ending of the parent alkane to the suffix-oic acid.

Example

Give the iupac names of each of the following carboxylic acids.

Carboxylic acids IUPAC Name

a) HCOOH methanoic acid

b) CH3COOH ethanoic acid

c) CH3CH2COOH propanoic acid

d)CH3CHCOOH 2-methylpropanio acid

            |

        CH3

Preparation of Carboxylic acids

Oxidation of primary

Primary alcohols are oxidized to produce carboxylic acid by a number of oxidizing agent,

such as chromium trioxide ( CrO3) and potassiumdichloridate (K2Cr2O7) in an equeous

acid solution

General formula carboxylic acid

 OH

  ||

R-C-OH

Carboxylic acid

Physical properties of Carboxylic acids

Carboxylic acids also exhibitmintermolecular hydrogen bonds since they possess a

hydrogenatom bonded to an electronegative oxygen atoms, Carboxylic acids often exist as

dimers held together by two intermolecular hydrogen bonds

The Carbonly oxygen atoms of one molecules as result

Carboxylic acids have higher boiling point and melting point than alcohols of similar mass

Reaction of Carboxylic acids

Esterification

. Alcohols react with Carboxylic acids in the presence of an acid catalyst to form ester in a

reaction known as estrification

General Equation

O                                O

||                               ||

C  OH +H  OR    H+ RC-OR+H2O

This is the syllabus of Somali Education Special Chemistry, Chapter F4 Three.