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Mineral nutrition

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Class 10 Class 12

What do you mean by:
(i) Elimination reactions
(ii) Rearrangement reactions?


(i) Elimination reactions: An elimination reaction is one which involves the loss of two atoms or groups either from the same or adjacent atoms of a substance leading to the formation of multiple bond i.e. double or triple bond. In such reactions at least two σ; bonds are lost and one straight pi; bond is created. These are two types:
(a) β-elimination reaction. Here loss of two atoms or groups takes place from the adjacent carbon atoms in the molecule. For example,

(i) Dehydrohalogenation of alkyl halides with an alcoholic solution of KOH.



(ii) Dehydration of alcohols in the presence of concentrated H2SO4 upon heating:



(iii)  straight alpha-Elimination reactions. In such reactions, there is loss or elimination of two atoms or groups from the same carbon atom in the molecule. For example.

(b) Dehydrohalogenation of chloroform with NaOH



(ii) Dehydrogenation of primary or secondary alcohols with reduced copper at 573K.



(iii) Rearrangement reactions Reactions involving the shift or migration of an atom or a group from one atom to another within the same molecule are called rearrangement reactions for example.
 (i) n-Butane rearranges to form 2-methyl propane when heated in a sealed tube in the presence of AlCl3/HCl.

CH subscript 3 space minus space stack CH subscript 2 with straight n minus Butane below space minus space CH subscript 2 space minus space CH subscript 3



(ii) Ammonium cyanate upon heating rearranges to form urea.


  


Classify the following transformations according to the reaction type.
straight H subscript 3 straight C space minus space CH space equals CH space minus space CH subscript 3 space plus space Br subscript 2 space rightwards arrow space space straight H subscript 3 straight C space minus space CHBr space minus space CHBr space minus space CH subscript 3


It is a Addition reaction.


Classify the following transformations according to the reaction type.
straight H subscript 2 straight C space equals space CH space minus space CH subscript 2 space minus space CH subscript 3 space rightwards arrow space space straight H subscript 3 straight C space minus space CH space equals space CH space minus space CH subscript 3


It is a Isomerisation reaction.


What do you understand by:
(i) Isomerisation reaction          
(ii) Condensation reaction?


(i) Isomerisation reaction. All those reactions in which interconversion of isomers take place without affecting the molecular formulae and carbon skeletons of reactants and products are called Isomerisation reactions. For example,



(ii) Condensation reaction. All those reactions in which two same or different organic reactants unite to give a product with or without the elimination of another, simple molecule are called condensation reaction. For example condensation of aldehyde or ketone.


Classify the following transformations according to the reaction type.


In this reaction, substitution takes place, followed by a rearrangment of atoms and groups of atoms.