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3. (a) Consider the bond-line (dash/wedge) structure shown below. Using the Newman projection templates provided to the right of this bond-line structure, draw the overall lowest energy (most stable) and overall highest energy (least stable) conformation possible in Newman projection form sighting down the C C, bond indicated. Provide a one sentence explanation to justify for the overall most stable conformation. (Ipts each correct Newman, 2pts for valid explanation) sight down Cy-- - bond .23 Lowest Energy (most stable) (b) Consider the bond-line structure shown below. Draw all three staggered conformations in Newman projection form in order of increasing stability. You may assume that a CH, is larger than a Bratom and a Bratom is larger than a Hatom. (2pts each correct Newman structure, 2pts correct order) sight down C, -C2 - Bi Br bond HNCH shown in an elipsed conformation Increasing Stability (c) Consider the Newman projection of the 1,2-disubstituted cyclohexane derivative shown below and answer parts (-iv). The carbons in the cyclohexane ring have been numbered for you. ipr - isopropyl; Me = methyl HSL Me Newman projection of a disubstituted cyclohexane derivative (Ipt) is the iPr group at C-l axial or equatorial? ( (Ipt) Is the CH, group at C-2 axial or equatorial? (iii) (2pt) Circle the bond-line structure below that best represents this compound. PriPr Me Me Pr (iv) (pt) is compound a cis or trans stereoisomer?

Answer 1

3.ca) to By rotating C2 C3 we get more stable and Reast stable conformation in Newmon projection - CH(CH3)2 CH(CH3), CH(CH3)₂ H H highest energy due to the steric or eclipsing strain between two.ips CH(CH3) lowest energ2 group? By 2, BY Hi n Hz & By rotatin] - co we get 3 staggered conformation, I I Br BY stability order in (1)) (11) > 15t). ( ) ipr 21 2Me i At C-1,-ips group is in axial position. (ii) At c-2, -me group is in equatorial position. (in) The best representative str. is - IV) The compount is cis stereoisomers."