copy of structure and bonding 9

1
Structure and Bonding Both are similar pK b stronger will be the base. A. Basicity of alcohols : The decreasing order of base strength in alcohols is due to +I effect of alkyl groups. ( CH 3 ) 3 COH ( 3 o ) >( CH 3 ) 2 CHOH ( 2 o ) ¿ CH 3 CH 2 OH ( 1 o ) ¿ CH 3 OH methyl/alcohol B. Reactivity of alkyl halide : + I effect of methyl group enhances – I effect of the halogen atom by repelling the electron towards tertiary carbon atom. H 3 C C CH 3 CH 3 X ¿ H 3 C CH CH 3 X ¿ CH 3 CH 2 X> CH 3 X Tertiary > Secondary > Primary > Methyl Electromeric effect The phenomenon of movement of electrons from one atom to another in multibonded atoms at the demand of attacking reagent is called electromeric effect. It is denoted as E-effect and represented by a curved arrow ( ) showing the shifting of electron pair. A =B E Reagent A B : When the groups linked to a multiple bond are similar, the shift can occur to either direction. For example, in ethylene the shift can occur to any one of the carbon atoms. H 2 C=CH 2 H 2 C C .. H 2 H 2 C=CH 2 H 2 C .. C H 2 Page 1

Upload: ajay00388

Post on 19-Nov-2015

6 views

Category:

Documents


7 download

DESCRIPTION

Electromeric effectThe phenomenon of movement of electrons from one atom to another in multibonded atoms at the demand of attacking reagent is called electromeric effect. It is denoted as E-effect and represented by a curved arrow ( ) showing the shifting of electron pair.

TRANSCRIPT

Structure and Bonding

stronger will be the base.A. Basicity of alcohols : The decreasing order of base strength in alcohols is due to +I effect of alkyl groups.

B. Reactivity of alkyl halide : + I effect of methyl group enhances I effect of the halogen atom by repelling the electron towards tertiary carbon atom.

Tertiary>Secondary > Primary> Methyl

Electromeric effectThe phenomenon of movement of electrons from one atom to another in multibonded atoms at the demand of attacking reagent is called electromeric effect. It is denoted as E-effect and represented by a curved arrow ( ) showing the shifting of electron pair.

When the groups linked to a multiple bond are similar, the shift can occur to either direction. For example, in ethylene the shift can occur to any one of the carbon atoms.

Both are similar

Page 1