C) B) 4) Consider the following cyclohexanes. Draw the most stable chair structure below, then perform a chair flip. CI Br Flip Flip Flip

4. Draw a chair conformation of the following molecules. Ring flip your original chair, and circle the more stable conformation. cis-1,2-dimethylcyclohexane trans-1-tert-butyl-3-ethylcyclohexane cis-1,4-diisopropylcyclohexane cis-1-butyl-3-methylcyclohexane

4. Draw the most stable conformation for each of the following substituted cyclohexanes; then, in each case, flip the ring and redraw the molecular in the higher energy chair conformation. Shown all conformation in Newman projections. Fill in hydrogens to indicate unsubstituted carbons. a) b) most stable conformation: higher energy conformation: á most stable conformation: higher energy conformation: 3 Da

1. Compound 1 is one isomer of 1,3-dicholoro-2,4,6-triisopropylcyclohexane. a) Draw both chair conformations of compound 1. State which is more stable. (An isopropyl group should be treated as 'larger' than a chloro group.) b) Draw the most stable achiral stereoisomer of this compound, in its most stable conformation. c) Draw the most stable chiral stereoisomer of this compound, in its most stable conformation. i-Pr i-Pr 1 i-Pr 'CI

Q1. (a) Give a systematic (IUPAC) name for the following compound. HINT: Convert to bond-line structure first. Show your work. (b) Draw anti and gauche conformations looking down the C3-C4 bond. Name: Newman Projection about C3-C4 bond Anti Conformation Gauche conformation

a) Sighting down the C3-C4 bond, draw the gauche (60 degrees) and anti (180 degrees) Newman projections of 2,4-dimethylhexane. b) Circle the conformation that you drew that is lower energy.

4. (a) Draw a skeletal (line-bond) structure for 3,4-dimethylhexane. (b) Draw a sawhorse representation of any staggered conformation of this molecule looking down the carbon-3 to carbon-4 bond. (c) Draw a Newman projection looking down the carbon-3 to carbon-4 bond of the same conformation that you drew as a sawhorse representation.

1) Use conformations A andB shown below to answer the following questions. Br. H Br H H H H H CI Conformation A Conformation B Newman projection conformation A a) In the space to the right above, draw a Newman projection looking down the carbon-carbon bond of conformation A. Part of the Newman projection has been drawn for you. b) Which conformation would be more stable (A or B)? c) Which conformation has greater steric strain? (A or B)? d) Circle all the terms that accurately describe conformation A. STAGGERED ECLIPSED GAUCHE ANTI e) Circle all the terms that accurately describe conformation B. STAGGERED ECLIPSED GAUCHE ΑΝΤΙ

Draw the planar (Haworth) structure for cis-1-ethyl-2- methylcyclohexane. (b) Draw the two ring - flipped chair conformations. (c) Circle the more stable chair conformation (circle both if they are equal in energy).  Draw the Haworth structure and the two ring-flipped conformations of 1, 2, 4- trimethylcyclohexane (Compound D) on the frames below, b) Circle the more stable chair conformation (circle both if they are equal in energy). Haworth Structure

3) Draw both chair conformations of the six membered rings below and circle the lowest energy conformation. If they are equal in energy circle both structures. Draw out all of the H atoms on your chair structure and clearly indicate the directionality for all of the H and non-H substituents. a) CH3 CH3 CH3 b) d) H3C e) HO HO OH OH OH OH