Question

Pre-Laberstory Quiz for Experiment 4 Conformational Analysis Lab Sectios: 1. Rank the following cyclic alkanes from most stable(1) to leas sable (4). pts) 2. From the sawhorse projections below, cincle the highest energy conformation for ethane. (2 pls) IH НН НН 3. Circle the chair conformation below that represents the lowest energy confiormation for cis-1,3- dimethylcyclohexane? (2 pts)

Answer 1

Among these cyclopentane is the most sable. In cyclopentane c - c - c angle is 108 degree so the angle strain = 1/2 (10 degree 28' - 108 degree) = + 0.44 ' For cyclohexane c - c - c angle is 120 degree. So the angle strain = 1/2 (10- degree 28' - 120 degree) = -5 degree 16' where 109 degree 28' is the normal tetrahedral angle. Now if we decrease the size of the ring then the angle strain increases. \r\n Hence, is the most stable. ^is least stable. So, the stability order is we know that eclipsed conformation has the highest energy. \r\n Here is also 1, 3 - syn diaxial interaction are present so it is also unstable but relatively stabler than former where 1, 3 syn diaxial interaction occur between two methyl group. Here two methyl groups occupy the equatorial position. So, there are no such 1, 3 - syn diaxial interaction present. So this conformation is \r\n stable. Here one methyl group is