Using Newman Projection, draw the eclipsed and gauche
conformation of the following compounds.
1. propane (C1-C2)
CH3CH2CH3
2. butane (C2-C3)
CH3CH2CH2CH3
Why are both of the conformational isomers with a 0o
and 120o dihedral angles considered to be in an eclipsed
conformation?
-In a Newman projection formula of propane (staggered
conformation), locate and describe any planes of
symmetry and axes of symmetry.
-In a Newman projection formula of propane (eclipsed
conformation), locate and describe any planes of
symmetry and axes of symmetry.
Draw the Newman projection of the following compound, looking down the indicated bond. (2) Label this Newman projections as a staggered or eclipsed conformation. (3) Rotate this Newman projection to draw the Newman projection of the most stable conformation of this compound. (3) Label this Newman projections as a staggered or eclipsed conformation. (4) Re-draw this most stable conformation in a wedge-dash form (as the original compound below is shown).
For 1,4-dibromobutane(c2-c3) draw the newman projection for
angle 0,60,120,180,240,300. Draw an energy graph.
Why is one staggered conformer more stable?
Why is one staggered conformer least stable?
Why is one of the eclipsed conformers more stable?
Why is one of the eclipsed conformers least stable ?
1. Draw the Newman projections for ethane and the C1-C2 bond of
propane.
2. Which of the projection in #1 would have the highest energy?
Why?
3. A chiral molecule requires a stereogenic center. What must be
true about a carbon atom in a molecule for it to be a stereogenic
center?
4. Based on the answer to #3, Draw the smallest acyclic chiral
alkane and using wedges, show it in the S configuration.
Consider 2-methylpentane, (CH3)2CHCH2CH2CH3 (analyzing the
C3-C4 bond):
Draw a Newman projection for the Gauche conformation.
Draw a Newman projection for the Anti conformation.
Draw the Newman projection for the highest energy conformation
of the C3-C4 bond of 2-methylpentane.
Using the newman projection of n-butane. construct an energy
diagram to show the varation in free energy of n-butane as the
dihedral angle made by C1-C2-C3-C4 is changed from 0 degrees to 360
degrees in 60 degree increment.begin with a staggered conformation
and to acquire the eclipse . Rotating in 60 degree increment draw
the energy change. draw the newman projection for each
conformation. what is the energy difference between the two most
stable conformations.
Draw both resonance structures of the most stable carbocation intermediate in the reaction shown. • You do not have to consider stereochemistry. • Do not include anionic counter-ions, e.g., I-, in your answer. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate resonance structures using the ↔ symbol from the drop-down menu.