Organic Chemistry

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15 Nov 2009 17:21:14 IST
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what ar conformations of n- butane and which is more stable and why
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what ar conformations of n- butane and which is more stable and why



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Dasvidaniya's Avatar

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15 Nov 2009 17:29:44 IST
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The illustration of butane above is represented by the newmann projection  below by designating the two middle carbons, one as the "front" and one as the "behind" carbon, and connecting the two end methyl groups accordingly.

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15 Nov 2009 17:35:03 IST
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In the most stable conformation, the two methyl groups lie as far apart from each other as possible with a dihedral angle of 180 degrees. This particular staggered conformation is called anti. The other staggered conformation has a Me-Me dihedral angle of 60 degrees and is called gauche. The gauche form is less stable than the anti form by 0.9 kcal/mol due to steric hindrance between the two methyl groups. Such an interaction is often referred to as a gauche-butane interaction because butane is the first alkane discovered to exhibit such an effect.

Madhusudan Chavan's Avatar

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18 Nov 2009 18:30:19 IST
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The conformations of butane are fully clipsed ( angle 0 or 360), gauche ( angle 60 or 300) , eclipsed ( angle 120or 240), and anti ( angle 180).Fully eclipsed is least  stable  about 18.4-25.5 kJ/mol than anti conformation. . gauche conformations are about 3.35 kJ/mol less stable than anti conformation.The eclipsed conformation is less stable than gauche by about 10.85 kJ/mol and than anti conformation by about 14.2 kJ/mol.

The diagramatic representation has already appeared.


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2 Oct 2012 18:34:30 IST
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theory conformation



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