CONFORMATIONAL ANALYSIS
Different spatial arrangements of atom in a molecule which are readily interconvertable by rotation of single bond are configuration.Configuration represent confirmer which are readily inter convertible to they are not be separated.
The study of existence of configuration in molecule and their physical and chemical property is k/as CONFIRMATION ANALYSIS.
The structure of confirmers is of 2 types
1.STAGGERD -: When tarsinal angle b/w 2 atom molecule is 60°.
2.ECLIPSED -: Group of front and rear carbon overlap.
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| Confirmational analysis |
Conformational analysis in ethane
*In the structure of ethane 3 hydrogen is bonded with both carbon
*In the special arrangements with bond is rotated 60° then total six types of structure is obtained in which three is staggered from and three is eclipsed from.
Conformational analysis in butane
*In the structure of n-butane hydrogen and 1 methyl group is present on both carbon.
*During conformational analysis after reaction of 60° in each time total 6 structure is formed in which full staggered is 1,fully eclipsed 1 , partial staggered 2 and portial eclipsed 2.
Energetic in n-butane
* In the confirmational analysis total 6 structure are form in which 3 is staggered from and other 3is edipsed.
* In staggered from no steric hindrance occurs so they are stable and their energy is low.
* But in the case of eclipsed from bilky group are comes closer and dur to steric hindrance their stability is reduce and potential energy is increase.
Conformational analysis in cyclohexane
Cyclohexane is a cyclic compound which show confirmational analysis by rotation or straining of bonds Mohr and Sachse in 1890-91 gives the idea of confirmational analysis in cyclohexane.
*After angel stain cyclohexane show 2 form of structure.
*The chair form is rigid and where it is trans form into boat form same angulr deformation is Nesserey.
*The energy barrier in this process is about 9-11 kd/mole.
*This value is large enough for each confirmation to retain its identity.
*The chair and boat form are triangle stain but because of difference in staining strain and border a position state the 2 form are different in energy content.
Energy in cyclohexane
*When chair form structure of cyclohexane is convert into boat form then they change into total five structure-
1. Chair
2. Half chair
3. Twisted boat
4. Half boat
5. Boat
*They energy of chair from is highest becoz this is similar to the eclipsed form.
*The energy of boat form is very less is about to 1.5 kcl.
Stereo isomerism in biphenyl compound ( Atrop isomerism)
*Those single bonded compound in which 2 cyclic group are bulky group present, they also show restricted rotation, that way these compound biphenyl also show stereo isomerism.
* Stereo isomerism in biphenyl compound is also k/as atrop isomerism.
* The term atrop isomerism consist of 3 words.
A + Trop + isomerism
A means NON
TROP means TERM
*It means those isomerism which can not tern into another axis.
Atrop isomerism in biphenyl
*There are basically 2 condition for spoeing atrop isomerism.
1. There should be any functional group or atom at the ortho position.
2. The group or atom should not be simiiat position 1 and 2,and 3 and 4.
*Diphenyl compound can be diverded into 2 equal half so they can be symmetrical if there is no any group at ortho position.
*But when different atom or group is attached with ortho position then will be asymmetrical and show atrop isomerism.
Stereospecific and steroselective reaction
*Those chemical reaction after which a stereo compound is form which is either may be destroyed or levo then this is called stereospecific reaction.
*In this type of reaction both dextro and levo compound can be synthesized in different proportion.
Stereo selective reaction
These chemical reaction after which only one dextro or one levo compound is form and which is 100% selective they are called Stereo selective reaction.
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