-Name the Ce cyclohexanes from yesterday, include cis and trans. Powest in energy. which conformer is the lowest energy. -Decide which of the two conformers is - From all 6, decide CH3 CH3 CH3 З CH3 CH3 CH3 1 66 CH3 5 ч CH3 CH3 H₂C CH3 A C ру CH3 С CH3 CH₂ ода при куда с Ч CH3 CH3 - CH3 CH3 - = – ZH₂C M CH3 CH3 CH3 по кра CH3 G CH3 СН3 CH3

Given cyclohexane in a chair conformation, construct the more stable conformation of cis-1-ethyl-2-fluorocyclohexane by filling in the missing atoms or groups. Use the numbering provided on the ring. 1 H T Answer Bank H 5 6 H ethyl H H 4 3 T H H

Consider the energy diagram showing the conformational analysis of propane and match the indicated position with the correct conformation below. 00000 - = 3 2 OIV OV Н. CH3 Н Н H пи m 0 dihedral angle energy 180 HH H Н II Н. H Н Ш CH3 H 180 HCH3 HXH Н IV HCH3 CH3 HXH Н V

5. Assume that the types of strain in the rotation about the C1-C2 bond in 1,2-dibromopropane have the following values. •Torsional strain = 20 kJ/mol •Steric strain between two Br substituents gauche = 13 kJ/mol •Steric strain between two Br substituents eclipsed = 16 kJ/mol •Steric strain between Br and CH3 substituents gauche = 8 kJ/mol •Steric strain between Br and CH3 substituents eclipsed (a) Perform a conformational analysis about the C1-C2 bond, analogous to the diagram in Figures 4-4 and 4-7 (Karty). Draw a full rotational energy profile (add E values in kJ/mol on y-axis) drawing each eclipsed and staggered conformation as Newmann projections i.e. 60° rotations for complete rotation about the C1-C2 bond. = 10 kJ/mol. E (kJ/mol) 0° 360 °