Ian R. Gould PRINTED FIRST NAME FINAL EXAM. MOs 8 /63 Extra Credit /5

Transcription

1 EM 233, Fall 2014 FINL EXM Ian R. Gould PRINTED FIRST NME NSWER PRINTED LST NME KEY SU ID or Posting ID Person on your LEFT (or isle) PRINT YUR NME N E PGE! RED TE DIRETINS REFULLY! USE LNK PGES S SRT PPER work on blank pages will not be graded... WRITE LERLY! MLEULR MDELS RE LLWED D NT USE RED INK DN'T ET, USE MMN SENSE! Li e N F Ne Na Mg Person on your RIGT (or isle) 1 /14 nomen... 9 /24 products 2 /18 acid/base /24 SN2 3 /26 chair /28 mxn2 4 /32 enantiomer /16 bde mxn1 5 / /27 hybrid 6 /30 isomers /25 spectrum 7 /18 acid/base... Ms 8 /63 Extra redit /5 e l Si P S l r K a Sc Ti V r Mn Fe o Ni u Zn Ga Ge s Se Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd g d In Sn Sb Te I s a Lu f Ta W Re s Ir Pt u g Tl Pb i Po t Rn amine alcohol (δ, ppm) small range range of values broad peak R N 2 R R R 3300 variable and condition dependent, ca. 2-6 δ N N peaks romatic r mainly usually strong N R R 2 R N Xe Infrared orrelation hart Total (incl Extra) / R Interaction Energies, kcal/mol Eclipsing / ~1.0 /Me ~1.4 Me/Me ~2.6 Me/Et ~ N R broad with spikes ~ broad ~ NR2 broad ~ (cm -1 ) NMR orrelation harts 2 X R N 2 NR X Gauche Me/Me ~0.9 Et/Me ~0.95 i-pr/me ~1.1 t-u/me ~2.7 pproximate oupling onstants, J (z), for 1 NMR Spectra lkyl 3 Y > 2 Y > 1 Y lkyl ~10 ~2 ~ ~8 ~2 ~7 3 Y > 2 Y > 1 Y 0 0 romatic NR 2

2 EMISTRY 233, Fall 2014 FINL EXM Question 1 (15 pts.) Give the IUP name for the following. Specify stereochemistry as appropriate NME (5S)-bromo-(4R)-methyl-3-propyl-(2E,6E)-octadiene Question 2 (18 pts.) Give the product of the following Lewis acid/base reaction. Indicate the Lewis/base and whether they are also onsted acids/bases, give the curved arrow pushing showing bond making/breaking and RIEFLY explain why the reactions would be exothermic or endothermic. L L 2 2 exothermic, the reaction releases the ring strain in the 3-memeberd ring Question 3 (10 pts.) For the following cyclohexane, draw the lowest energy chair conformation (only) Me Et Me Et lowest energy Question 4 (16 pts.) Give the Lewis structure for (2R)-bromo-(3R)-methylpentane, with stereochemistry indicated using wedged/dashed bonds as appropriate, ND, draw a Lewis structure of its enantiomer (clearly indicate which structure is which) structure enantiomer

3 EMISTRY 233, Fall 2014, FINL EXM Question 5 (44 pts) Solvolysis of both bromides and form the same ether, as shown below a) Draw a full -curved arrow-pushing mechanism for each reaction, at each intermolecular step indicate the Lewis acid and base and whether they are also onsted acids and bases. Include all reasonable resonance contributors for intermediates as appropriate Me Me Me heat heat L/ Me Me L Me L/ L b) Draw a properly labelled reaction energy diagram for T reactions on the SME diagram, LERLY indicate which diagram refers to which reaction LERLY INDITE TE TIVTIN ENERGY FR TE RTE DETERMINING STEP FR E RETIN Energy c) RIEFLY explain which reaction would be faster, or Reaction oordinate in the rate determining step in, the product is a secondary cation, whereas in the cation is resonance stabilized, the rate determining step in thus has a lower activation energy, reaction is thus faster

4 EMISTRY 233, Fall 2014 FINL EXM NME Question 6 (16 pts.) 1. Determine whether the following structures are identical, enantiomers or diastereomers 2. Identify any meso compounds. 3. Give the absolute configuration at each chiral (asymmetric) center R meso S S S diastereomers Question 7 (22 pts.) For the following two reactions a) give the curved arrow pushing showing bond making/breaking and indicate the Lewis acids/bases (L/L) and whether they are also onsted acids/bases (/) b) one of these reactions is endothermic, the other is exothermic, indicate which is which and give a brief explanation for WY each reaction is exothermic or endothermic L/ L + L/ + L + reaction is exothermic, it makes a bond reaction is endothermic, it makes a bond and breaks a bond, but the negative charge is transferred from the more electronegative oxygen to less electronegative boron Question 8 (24 pts.) a) Draw pictures of the wavefunctions of the molecular orbitals requested, on the molecules. In each case indicate the..'s used to make the M..'s. - p - sp 2 - sp - p - sp 3 3-1s - π orbital - σ orbital indicated by the arrow - σ* orbital

5 EMISTRY 233, Fall 2014 FINL EXM NME Question 9 (70 pts.) Give the missing major RGNI PRDUT for each reaction a) Show all stereochemistry as appropriate, identify any MES compounds b) iefly explain whether and why a solution of the product would be optically active or not c) assign each reaction as, elimination, substitution or rearrangement a) l 3 + Na DMF 3 substitution optically active single enantiomer formed b) (±) racemic mixture c) RR achiral d) 1. 3.TF 2. / 2 2 optically active single enantiomer formed e) Ph Ph 2 Me Me Ph Ph Pd/ Me Me meso compound formed f) 2 hν (±) substitution racemic mixture formed g) 2 Me (solvent) Me (±) racemic mixture

6 EMISTRY 233, Fall 2014, FINL EXM NME Question 10 (32 pts). For nucleophiles going down the periodic table, nucleophilicity and basicity follow exactly the same trend in polar PRTI solvents, but follow PPSITE trends in polar PRTI solvents. Use this information to answer the following questions. a) Draw a reaction energy diagram for T reactions and on the SME diagram, clearly indicate T activation energiess ND both reaction exothermicities. Explain which reaction would be faster (both reactions are exothermic because the tosylate anion - Ts is very stable, and ignore the ammond postulate). Ts Na l DMF Ts Na + Na Ts DMF l- is a stronger base than - because it is smaller and makes stronger bonds, the lreaction is thus more exthermic, in the DMF polar aprotic solvent it is also a stronger nucleophile, and so the reaction is faster relative energy Na + - X Ts l + Na Ts l reaction coordinate c) Now do the same for reactions and D below, and explain why the nucleophilities are different in polar protic versus polar aprotic solvents (both reactions are exothermic and again ignore the ammond postulate) Na l Ts l + Na Ts Me D Ts Na Me l- is a still a stronger base than - in the protic solvent and thus reaction is still more exothermic, but in the polar protic solvent l-is a weaker nucleophile because it is more highly solvated + Na Ts relative energy Na + - X Ts D D D l reaction coordinate

7 EMISTRY 233, Fall 2014 FINL EXM NME Question 11 (38 pts.) a) For the reaction shown, give a curved arrow mechanism and indicate the Lewis/onsted acids and bases at each step as appropriate, and indicate the the number of steps and transition states associated with your mechanism L/ L/ 2 (solvent) l cat. L L/ L/ L depends upon mechanism how many steps are there in your mechanism? depends upon mechanism how many transition states are associated with your mechanism? b) Draw a reaction energy diagram, indicate the positions and relative energies of the starting materials, intermediates and products and LL TRNSITIN STTES, but Do not draw the structures of any transition states c) n your diagram, indicate the activation energy for each step in the mechanism and the reaction and clearly indicate the rate determining step Energy I1 Ea 2 I2 Ea R.D.S. Ea 3 I3 Ea 4 Reaction oordinate

8 EMISTRY 233, Fall 2014 FINL EXM NME Question 12 (28 pts.) a) Rank the three indicated bonds, and in order of increasing bond dissociation energy. Draw an energy diagram for cleavage of all TREE bonds and give a RIEF explanation for your choice of ranking < < lowest DE Energy highest DE - bond distance homolytic cleavage of - bond () generates a 1 radical which is the least stable radical, cleavage of - () generates a more stable 3 radical, cleavage of - () generates a tertiary ND resonance stablized radical, lowest in energy, it takes less energy to break bonds that form more stable radicals b) For the structure below, give the curved arrow pushing and the products of homolytic cleavage for the - bond that has been added to the line-angle structure (include all resonance contributors as appropriate) Question 13 (14 pts.) Give the hybridization of the NITRGEN atom in acetonitrile (structure given below), and show that you understand the meaning of the hybridization assignment by making a small table that summarizes all of the valence hybrid (and any unhybridized) atomic orbitals associated with this nitrogen atom, and state how they are used (e.g. used to make a sigma bond to the chlorine, I know there is no chlorine in the structure, this is just to show you what do to) 3 N the nitrogen is sp hybridized sp - σ-bond to hydrogen sp - non-bonding electrons p - π-bond #1 to carbon p - π-bond #2 to carbon Extra redit (5 pts.) Which of the following drugs resulted in terrible birth defects in Europe in the 1960s? ibuprofen thalidomide ketamine thebaine

9 M 233, Fall 2014, Final Exam NME Question 14 (28 pts) Provided are spectra for a compound with molecular formula a) Give the degrees of unsaturation 1 degree of unsaturation b)n the infrared spectrum, indicate the peaks that identify the functional groups in the molecule (including (sp 3 )-). Indicate T the functional group, and where appropriate, the specific ND in the functional that corresponds to the peak. (sp3) = c) draw the structure and clearly indicate which hydrogens correspond to which signals in the proton nmr spectrum (only) 6 doublet d 3 d 3 triplet 3 a 2 b c 3 c 1 multipet b 2 quartet a