1,3 proto-tropic shifts and difference between tautomerism and resonance
What is 1,3 proto-tropic shifts?
Isomer which are inter-convertible, are differ from each other
only in electron distribution and in the position of a relatively mobile groups
or atoms are called tautomerism.
The mobile atom is in the great majority of example is hydrogen and the
phenomenon is referred to as proto-tropic shifts and usually the proton in a
triad system is from 1 to 3 position in the chain and hence it is called 1,3 proto-tropic shifts.
Few examples of 1,3 proto-tropic shifts
in triad system are as follows,
What is difference between tautomerism and resonance ?
When two structural isomers are converted to each other very rapidly keeping up equilibrium state between them, then these two isomers are called tautomers and this phenomenon is called tautomerism.
For examples, keto-enol tautomerism, valence tautomerism etc.
It is a phenomenon which occurs really. Tautomers have existence and they are isolable.
There is a thermodynamic equilibrium between tautomers .As
tautomers are different compound the question of lowering energy does not
arise.
Resonance
When a
molecule can’t be completely represented by a single structure but its characteristic
properties can be described by two or more indivisible structures, then the
real structure is known as resonance hybrid of these structures and this phenomenon
is called resonance.
For example, resonance and resonating structure of aniline molecule
are shown below.
It is a hypothetical state of matter. Resonating structures are hypothetical and non isolable.
There is no equilibrium between resonating structures. Resonance
reduces the energy of the entity.
Summary
- what is proto-tropic shipts ?
- what is resonance ?defined resonance energy .
- what is tautomers and tautomerism ?
No comments