Midterm #3. Ian R. Gould PRINTED FIRST NAME. Extra Credit /5

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1 EM 233, Fall 2014 Midterm #3 Ian R. Gould PRITED FIRST ME SWER PRITED LST ME KEY SU ID or Posting ID Person on your LEFT (or isle) PRIT YUR ME E PGE! RED TE DIRETIS REFULLY! USE LK PGES S SRT PPER work on blank pages will not be graded... WRITE LERLY! MLEULR MDELS RE LLWED D T USE RED IK D'T ET, USE MM SESE! Li e F e a Mg e l Si P S l r K a Sc Ti V r Mn Fe o i u Zn Ga Ge s Se r Kr Rb Sr Y Zr b Mo Tc Ru Rh Pd g d In Sn Sb Te I Person on your RIGT (or isle) 1 /12 nomen 2 /25 RED 3 /32 rxns 4 /20 radical 5 /20 MR 6 /38 mxn2 7 /28 spectrum Extra redit /5 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 2 R R R variable and condition dependent, ca. 2-6 δ peaks romatic r mainly usually strong R R 2 R Xe Infrared orrelation hart Total (incl Extra) / R Interaction Energies, kcal/mol Eclipsing / ~1.0 /Me ~1.4 Me/Me ~2.6 Me/Et ~ R broad with spikes ~ broad ~ R2 broad ~ (cm -1 ) MR orrelation harts 2 X R 2 R 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 MR Spectra lkyl 3 Y > 2 Y > 1 Y lkyl ~2 ~10 ~ ~8 ~2 ~7 3 Y > 2 Y > 1 Y 0 0 romatic R 2

2 EMISTRY 233, Fall 2014, MIDTERM ME Question 1 (12 pts.) Give the IUP name for the following structure. Ph r bromo-4-methyl-3-phenyl-(3Z)-octene Question 2 (25 pts.) dd the curved arrows to indicate bond making/breaking for the reactions and, indicate the Lewis acids/bases (L/L) and if they are also ronsted acids/bases (/) L/ L/ r 3 3 L/ 3 2 L/ + r 3 3 (Z)-7-bromo-4-methyl-3-phenyl-3-octene 7-bromo-4-methyl-3-phenyloct-(3Z)-ene (Z)-7-bromo-4-methyl-3-phenyloct-3-ene + r r 3 3 b) Draw a reaction energy diagram with properly labelled axes for T reactions on the SME diagram, clearly indicating which is and which is, indicate the activation energy for both reactions, D, the reaction exothermicities or endothermicities as appropriate. Indicate the positions of T transition states (but do not draw them). Energy (earlier) faster slower (later) ΔE ΔE Reaction oordinate c) RIEFLY explain why one of these reactions is more exothermic or more endothermic than the other one, D, which reaction would be faster, your explanation should include the term "ammond postulate" both are endothermic since both break 2 bonds and make only 1 bond, reaction starts higher in energy because this alkene is less substituted, reaction is thus less endothermic, according to the ammond postulate the less endothermic reaction will have the smaller activation energy and thus be faster

3 EMISTRY 233, Fall 2014 MIDTERM ME Question 3 (32 pts.) Give the missing major organic products R reagents/conditions as appropriate for each of the following reactions. lassify each reaction as addition, elimination, substitution or elimination, LERLY IDITE STEREEMISTRY IF PPRPRITE a) r 2 hν r substitution b) 1. 3.TF or... addition Ph 2. / 2 2 Ph Ph 1. g(c) 2 / 2 c) addition 2. a 4 d) 2 l (catalytic) addition Extra redit (5pts) Light is used in photobromination and photochlorination reactions. Light was also mentioned in one of the "Real Life" pages to do which of the following? make a polymer make a hydrocarbon make a benzene ring make D

4 EMISTRY 233, Fall 2014, MIDTERM ME Question 4 (20 pts.) Give a curved arrow pushing mechanism for the following reaction. learly indicate the initiation and propagation steps (but do not include any termination steps), add atoms to the line angle structures as necessary and include any important resonance contributors for any intermediates. r hν r 2 + r + r r 2 r initiation step r r + propagation steps r r r + r Question 5 (20 pts.) ssign signals,, and D in the proton nmr spectrum to the appropriate protons on the phenol structure provided. Using drawings of minor resonance contributors, explain why the 2 signal labelled has a larger chemical shift than the 2 signal labelled. Your explanation must include the following terms: "electron density", "local magnetic field", "shielding" and "deshielding" 2 1 singlet 2 doublet D 1 D phenol δ the minor resonance contributors show that there is a partial negative charge on the carbons that carry, these hydrogens see higher ELETR DESITY which results in MRE SIELDIG which results in a SMLLER LL MGETI FIELD which results in less DESIELDIG and thus a smaller chemical shift

5 EMISTRY 233, Fall 2014, MIDTERM ME Question 6 (38 pts) For the provide reaction, give a curved arrow-pushing mechanism, indicate the Lewis acid and base (L, L) at each step where appropriate, and whether they are also ronsted acids and bases (, ), LERLY indicate the RTE DETERMIIG STEP L/ reactants rate detn step L/ 2 (solvent) l cat. see EXT PGE for an explanation for this question product L/ I1 L L I2 I3 L/ b) ow many steps are there in your mechanism? depends upon the mxn c) ow many transition states are associated with your mechanism? depends upon the mxn d) Draw a reaction energy diagram for your mechanism, indicate the positions of the reactants, prodicts and any intermediates (don't redraw the structures, you can circle the items on the mechanism and use arrows, or use symbols such as I1 for intermediates 1 etc.). Indicate the TIVTI EERGY FR E STEP, the RETI EXTERMIITY and the RTE DETERMIIG STEP. Energy 1 rate detn step I1 2 3 I2 reactants exothermicity I3 4 product reaction coordinate e) Draw below the TRSITI STTE for the rate determining step (only)

6 So, as you may have guessed, I completely messed up this question! I re-wrote the question several times going back and forth between a hydride shift and an alkyl shift, and I eventually settled on making it an alkyl shift, except that I forgot to go back and put into the starting structure the alkyl groups that are needed to do the shift! TIS is what the problem was supposed to be (with the 2 extra methyl groups in blue): 2 (solvent) l cat. L/ L L L/ Without the blue methyl groups, a carbocation rearrangement is not even required with the structures given, but if you did the methyl shift you were not marked incorrect because the problem invited you to do so... The grader was told to allow multiple correct answers to this qusstion, even some that were not technically correct!

7 EMISTRY 233, Fall 2014 MIDTERM #3-6 - ME Question 7 (28 pts) Provided are spectra for a compound with molecular formula a) Give the degrees of unsaturation 5 degrees b) n the infrared spectrum, indicate which peaks correspond to which functional groups (including (sp 3 )-). Indicate T the functional group, and where appropriate, the specific D in the functional group that corresponds to the peak sp c) draw the structure and clearly indicate which hydrogens correspond to which signals in the proton nmr spectrum (only) 4 peaks in this region 3 peaks in this region D 2 F E 3 D F 1 2 doublet 2 E 2 sextet