Question

Question 1 (1.5 pts] The total strain energy of conformation A is 10.5 kcal/mole (R denotes the same unspecified alkyl group). What strain energy (in kcal/mole) is associated with a single R:R 1,3-diaxial interaction? Please enter just the numerical value rounded to one decimal place. Please do not include units H HT HUT HHHH HH Conformation A Question 2 (1.5 pts] Rank conformations B, C and D from most stable to least stable (most stable first). IC H (CH2CH2CH3)3 CH(CH3)2 =o- Xh LH HH H HH IH HH HH Conformation B Conformation C Conformation D Question 3 [1.5 pts] Which one of the following statements about structure E is correct? Structure E Structure E is optically active Structure E is not optically active O

Answer 1

Totat strain for cyclohexane = Bond angle strain + tortional strain + Stevic strain d sleoüc struy means Gauche, stray and qual-awal (113) interratection. Highear strain energy molecules is lower stable Lower strain eveorgy molecules are to more stable. Gauche strain present between adjucent bulty groups. Example MTH me, me groups have some steoùc liudiyeule, slearic me ! -Me steric Given molecule R- -- RH cyclotesame molecule contains was no bond angle straîn and no tortional strain for this molecule, there is no Gauche strain because at 1,2 positions a bulky groups not presenta only one alkyliggroup se poresent. Total strain = 1,3-achal, axial strain energy (only two axial 10.5 kcal/mol = 2(RIR) acial strin present ** R/R = 10,5 kcalleol - $ 5.25 kcal/mole

CH (CH). H Hal More bulky groups are have more energy so less stable losseo bulky groups (small groups) laue Loveeoy cuergy so lighed (more) stable. Bulky groups are always present in equatorial position they only the go molecule is strain free -stable. If antal present du anal position the molecule is hang some sta strain (1,3-anial ruteractions) - less stable. in aboue B,C,D groups all groups prosent ſu anial. So compare thee boulikeforegs bulkiness between the molecules More bulky group - less stable lower bulky group - Move stable. Bulkiness ordeol ) -C(CH2CH.CH3), > -CH(CH3)-cc* stability order c o B (bulky) en structure ich optically mactive because the plane cutting to the molecule into two equal parts. plane passing through os molecule and (6 (05) and culling traiangle two parts.