09-25 - Choose the correct formula for the following...

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Unformatted text preview: 9/28/2009 Choose the correct formula for the following bicyclic structure: = CnH2n+2 - 2(number of rings) n=9 = C9H2(9)+2  2(2) = C9H16 = A. C10H20 B. C9H18 C. C10H22 D. C9H16 E. C10H18 1 Nomenclature: Choose the correct formula for the structure on the right: bridgehead constitutional constitutional isomers isomers bicyclo [4.3.0 ] nonane 4.3. 3.0 A. bicyclo[4.3.0]nonane A. bicyclo[4.3.0]nonane C. bicyclo[2.2.0]nonane C. bicyclo[2.2.0]nonane B. bicyclo[4.3.0]nonane B. bicyclo[4.3.0]nonane D. bicyclo[3.2.2] D. bicyclo[3.2.2] nonane 2 How does a chemical formulas change if the compound contains oxygen and/or nitrogen? O CH CH3 H H C HH C CH CH3 C H H CH CH3 Hydrocarbons are rare in organic chemistry. How does this formula change when the structure contains oxygen and nitrogen? O CH CH3 H H C HH C CH CH3 C H H CH CH3 = C9H20 H3C C H H C = C9H20 H3C C H H C C9H20 C9H20 OH OH O 3 C9H20O, an ether C9H20O, an alcohol 4 Hydrocarbons are rare in organic chemistry. How does this formula change when the structure contains oxygen and nitrogen? CH CH3 H H C HH C CH CH3 C H H CH CH3 What is the molecular formula of Cortisone? 12 20 OH 18 17 19 13 16 H OH 14 8 7 O O 1 2 21 10 4 5 9 11 = C9H20 H3C C H H C H 6 H 15 C9H20 O3 When nitrogen is present the hydrocarbon contains one more hydrogen. H N H cortisone = C21H44  2(8)O5 = C21H28O5 A. = C21H30O5 B. = C21H26O5 E. = C21H42O5 C. = C21H28O6 F. = C21H28O5 7 N C9H21N, a 2° amine H C9H21N, a 1° amine 5 D. = C22H28O5 1 9/28/2009 Exam 1 Review Javits 100 Today 4:30 10 Conformational Analysis. The shape of molecules. Chymotrypsin primary structure MASLWLLSCFSLVGAAFGCGV PAIHPVLSGLSRIVNGEDAVPG SWPWQVSLQDKTGFHFCGG SLISEDWVVTAAHCGVRTSDV VVAGEFDQGSDEENIQVLKIA KVFKNPKFSILTVNNDITLLKLA TPARFSQTVSAVCLPSADDDF PATLCATTGWGKTKYNANKTP DKLQQAALPLLSNAECKKSW GRRITDVMICAGASGVSSCMG DSGGPLVCQKDGAWTLVGIVS WGSDTCSTSSPGVYARVTKLI PWVQKILAAN tertiary structure 11 How many isomers of ethane (C2H6) exist under H standard conditions? H Which of these two structures would you predict to be more stable? H H C HH C H C H 60º C H H H HH C C H A = yes B = no 12 H C HH A eclipsed H C HH H C HH B HH C H HH HH Are the above structures identical? staggered These two structures are two different conformations of ethane. isomers = compounds with the same formula but different structures. 13 isomers = compounds with the same formula but different structures. What are the factors affecting conformational stability? H Steric Effects H C H H H H C H H What are the factors affecting conformational CH CH stability? energy Electronic Effects (bonding) torsional strain LUMO LUMO steric effects! HOMO HOMO eclipsed A B staggered eclipsed A B staggered If steric effects are important what structure would 14 be more stable? If electronic effects are important what structure would be more stable? 15 2 9/28/2009 What are the factors affecting conformational stability? Electronic Effects (bonding) Can these two isomers be separated from each other? A = yes B = no bonding MO H C H C HH eclipsed bonding MO H C HH C H MO anti bonding HH A HH B staggered MO anti bonding If electronic effects are important what structure would be more stable? 16 17 Can these two isomers be separated from each other? A = yes B = no Can these two isomers be separated from each other? A = yes B = no energy 12.6 kJ (3 kcal)/mol 18 rotation 19 Can these two different structures be separated from each other under standard conditions? an energy maximum (eclipsed) torsional strain an energy minimum (staggered) an energy minimum (staggered) What are Newman Projections? H H H H H H H H H H H H H H H energy 12.6 kJ (3 kcal)/mol energy 12.6 kJ (3 kcal)/mol rotation 20 rotation 21 3 9/28/2009 What are sawhorse Projections? What are sawhorse Projections? HH H H C C H HH C C H H H HH H HH C C H HH HH C C H H torsional strain energy 12.6 kJ (3 kcal)/mol energy HH 12.6 kJ (3 kcal)/mol rotation 22 rotation 23 Draw the sawhorse projection of the following Newman projection. Cl Cl H H H H Cl C H H Cl Cl Cl H C H C Cl Cl H C HH H Cl Cl C H Cl Cl H C HH C H Cl Cl H C C H Draw the sawhorse projection of the following Newman projection. Cl Cl Cl Cl Cl Cl H H H Cl Cl C H Cl H H H Cl Cl Cl H C H C Cl Cl H C HH H H H H Cl H Cl Cl C H Cl Cl H H H H Cl Cl H H Cl Cl H C HH C H H H a partial structure H C Cl H Cl Cl H C Cl Cl H Cl Cl A B C D A B C D What sawhorse projection is identical to the above Newman projection? 24 What sawhorse projection is identical to the above Newman projection? 25 Butane has two staggered conformations. Which is more stable? H HH C H H C H C C HH H H H H HH C C H C Butane has two staggered conformations. Which is more stable? H HH C H H C H C C HH H H H H HH C C H C A CH H HHH B CH H HHH staggered anti staggered gauche 26 staggered anti staggered gauche 27 4 9/28/2009 In contrast to ethane butane has two staggered conformations. Which is more stable? H HH C H H C H C C HH H H H H HH C C H C CH HHH H In contrast to ethane butane has two staggered conformations. Which is more stable? H HH C H H C H C C HH H H H H HH C C H C CH H HHH staggered anti staggered gauche 28 staggered anti 29 In contrast to ethane butane has two staggered conformations. Which is more stable? H HH C H H C H C C HH H H H H HH C C H C In contrast to ethane butane has two staggered conformations. Which is more stable? CH CH3 CH CH 2 CH CH 2 CH CH3 CH H H HH energy 14.6 kJ /mol 3.8 kJ /mol 21 kJ /mol staggered anti staggered gauche 30 rotation 31 How many stable staggered conformations exist for butane? A. 1 CH CH3 CH CH 2 How many stable staggered conformations exist for butane? B. 2 CH CH 2 CH CH3 C. 3 D. 4 E. 5 F. 7 Although the two gauche conformations have the same energy they have different structures. energy 14.6 kJ /mol 3.8 kJ /mol 21 kJ /mol energy 14.6 kJ /mol 3.8 kJ /mol 21 kJ /mol rotation 32 rotation 33 5 9/28/2009 What is major factor responsible for the energy difference between the staggered and eclipsed conformers? A. Steric Effects (non bonding) B. Torsional Effects (electronic) What is major factor responsible for the energy difference between the staggered and eclipsed conformers? torsional strain 12.6 kJ /mol steric strain 14.6 kJ /mol energy energy 14.6 kJ /mol 3.8 kJ /mol 14.6 kJ /mol 3.8 kJ /mol 21 kJ /mol rotation 34 rotation 35 6 ...
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  • Conformational isomerism, Cl Cl, Cl H H H Cl Cl Cl H C H C Cl Cl H C HH H H H H Cl H Cl Cl C H Cl Cl H H H H Cl Cl H H Cl Cl H C HH C H H H, H H H Cl C H H Cl Cl Cl H C H C Cl Cl H C HH H Cl Cl C H Cl Cl H C HH C H Cl Cl H C C H

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