Aldehyde, Ketone, Carboxylic acid : class X

Aldehyde, Ketone, Carboxylic acid : class X chemistry

ALDEHYDE  And  Its IUPAC Naming :

• Structural formula  : (  R—CHO )  , where  R  is hydrogen  or  any alkyl group

• Aldehyde are the organic compounds whose molecules consist  ---CHO group at one end of root (chain ) .

• The general formula of the homologous series of aldehyde is C_nH_2nO, where ‘n’ is natural  number.    For example, if  n = 1  , then formula of this aldehyde will be H-CHO

• The two simple aldehyde are Formaldehyde  HCHO (methanal) and acetaldehyde  CH₃CHO (ethanal).

How to name  Aldehyde compound:

• Step -1 : Determine root of aldehyde molecule  .

• Step -2:  Count number of carbons present in root  and then decide its root name.

• Step -3 :Give number the carbon atoms of root from carbon of  ---CHO group.

 Name the compound in proper order:  branch name,  root name,  family name.

  

  aldehyde examples:

Naming of  HCHO

Root name : meth

Family name : anal

So IUPAC  name  :  methanal

Common name:   Formaldehyde

Naming of CH₃CHO_: 

CH₃ ----- CHO

Root name : eth

Family name : anal

So IUPAC  name  :  ethanal

Common name  :  Acetaldehyde

Naming of C₂H₅CHO_: 

CH₃ --- CH₂ --- CHO

Root name : prop

Family name : anal

So IUPAC  name  :  propanal

Naming of C₃H₇CHO_: 

CH₃ --- CH₂ ---CH₂—CHO

Root name : but

Family name : anal

So IUPAC  name  :  butanal

Ketone group : 

• Structure formula :   ( R—CO—R’ ),     where R  and  R’  are alkyl groups.

• Ketone are the organic compounds whose molecules consist  ---CO--  group between the root (chain ) .

• The general formula of the homologous series of aldehyde is C_nH_2nO, where ‘n’ is natural number and greater than two.   For example, if  n = 3 , then formula of this ketone will be  C₃H₆O    or  CH₃—CO—CH₃

• The  simple ketone are Acetone  CH₃—CO—CH₃ (propanone )

Ketone naming :

• Step -1 : Determine root of Ketone molecule  .

• Step -2:  Count number of carbons present in root  and then decide its root name.

• Step -3 : Give number the carbon atoms of root from that end so that  carbon of  ---CO--  group gain minimum number.

 Name the compound in proper order:  branch name,  root name,  family name.

Example :

Naming of  CH₃—CO—CH₃

Root name : prop

Family name : anone

So IUPAC  name  :  propanone

Common name:   Acetone  or  dimethyl ketone

Naming of CH₃—CO—C₂H₅   or

CH₃—CO—CH₂--- CH₃

Root name : but

Family name : anone    or   suffix - one

So IUPAC  name  :  2-butanone or  butanone-2  or butan-2-one

Common name  :  ethyl methyl ketone

Naming of C₂H₅—CO—C₂H₅  

Root name : pent

Family name : anone

So IUPAC  name  :  3-pentanone   or  pentanone-3

Common name   :    diethyl ketone

Carboxylic Acid : (Organic Acid )

• Structure:  R- COOH

• Carboxylic Acid are the organic compounds whose molecules consist  ---COOH  group at one end of  root (chain ) .

• The general formula of the homologous series of Carboxylic Acid  is C_nH_2n+1 COOH,  where ‘n’ is whole number.   For example,  if  n = 0 , then formula of carboxylic acid  will be  HCOOH

• The  simple carboxylic acid  are Formic Acid  (  HCOOH )  and  acetic acid CH₃COOH.

How to name  Carboxylic Acid  compound:

• Step -1 : Determine root of carboxylic acid  molecule  .

• Step -2:  Count number of carbons present in root  and then decide its root name.

• Step -3 :Give number the carbon atoms of root from carbon of  ---COOH  group.

•  Name the compound in proper order:  branch name,  root name,  family name.

Example :

Naming of  H—COOH

Root name : meth

Family name : anoic acid

So IUPAC  name  :  methanoic acid

Common name:   Formic acid

Naming of CH₃—COOH  

Root name : eth

Family name : anoic acid    and  suffix – oic acid

So IUPAC  name  :  ethanoic acid

Common name  :  acetic acid

Naming of C₂H₅—COOH  

Root name : prop

Family name : anoic acid

So IUPAC  name  :  propanoic acid

Ethanoic Acid: CH₃—COOH  

• It is second member of carboxylic acid family.

• Its common name is acetic acid.

Physical Properties :

• It is colorless liquid which has sour taste.

• Its smell is like a vinegar.

• Ethanoic acid is miscible with water in all proportions.

• Its boiling point is 118⁰ C

Chemical Properties:

    Change colour of Indicators:

• Acetic acid turns blue litmus red.

• Acetic acid turns universal indicator paper to orange.

Reaction With Metal Carbonate:

• Acetic acid reacts with metal carbonate to form salt, CO₂  and  water.

• The salt formed in this reaction is sodium ethanoate whose common name is sodium acetate.

 Reaction With Metal Bicarbonate:

• Acetic acid reacts with metal bicarbonate to form salt, CO₂  and  water.

• This reaction is used to test of acetic acid because of :

1. Brisk effervescence of carbon dioxide gas is produced. 
2. Only carbon dioxide  gas turns lime water milky.

Reaction With Sodium Hydroxide:

• Acetic acid reacts with sodium hydroxide to form salt  and  water.

   

Reaction With Alcohol :

• Acetic acid reacts with ethyl alcohol  in presence of few drops of concentrated H₂SO₄  to form ester.

This reaction is occurred on heating reactants. 

• This reaction is called esterification. 
• In this reaction , ester is formed which has sweet smell. 
• This reaction is carried out for test of Alcohol  and ethanoic acid.

Mechanism 

Ester:

• Esters are usually volatile liquids having sweet smell  ( fruity smell ).

• These are used in making artificial perfumes.

• These are used as flavoring agent in ice creame, cold drinks , sweet etc.

• When an ester is heated with sodium hydroxide solution then ester gets hydrolyzed  to form alcohol  and sodium salt of carboxylic acid.

• The alkaline hydrolysis of esters is known as sponification .this reaction is used for making soaps.  

Other member of ester family

IUPAC name of some ester

Related Article ( Click to read )

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• HYDROCARBON Organic Chemistry Revision Notes

• IUPAC- Nomenclature Basic Concept

• Nomenclautre of Hydrocarbons (Alkane , Alkene, Alkyne)

• ALCOHOLS - Organic compounds