Dihedral Angle for Ethane httpwww2chem ucalgarycaFlashethanehtml Torsional Strain strain increase in energy due to eclipsing groups eclipsed staggered Conformations of Propane brPage 3br Staggered conformations Energy vs Dihedral Angle for Propane D ID: 81332
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Total Strain Energy1151102702742545000 Chair cyclohexane has two types of hydrogens: axial: C-H axis is ÒperpendicularÓ to the Òplane of the ringÓaxialequatorial half-chairhalf-chairEnergy Profile for the Chair-Chair Interconversion of Cyclohexanehttp://www2.chem.ucalgary.ca/Flash/cyclohexane.htmlboatBoat cyclohexane (29 KJ/mol higher than chair)no angle strain, considerable torsional strain, some steric strainTwist-boat cyclohexane (23 KJ/mol higher than chair) some torsional and steric strain relieved from the boat or Keq= 0.01 (99 : 1)HCH3HCH3cis (two equatorial)HCH3trans (one equatorial, one axia 1,3-disubstituted1,4-disubstitutedHCH3HCH3trans (two equatorial)HCH3cis(one equatorial, one axial)HH3Ccis(one equatorial, one axial)trans(two axial)CH3 Obridgeheadcarbonstwo 2-carbon bridgesand one 1-carbon bridgeC aaaCYCLOHEXANE: For cyclohexanes you may be asked to draw a chair, in which case all substituents must be either axial or equatorial. The following is the correct way to draw chair cyclohexane. Note how the axial and equatorial substituents off each carbon are represented. Disubstituted chair cyclohexanes: correctincorrect¥¥¥¥aaeeaaeeaeaetranstranscistransciscistranstrans