**YOU ARE NOT ALLOWED TO TAKE SPARE COPIES OF THIS EXAM FROM THE TESTING ROOM**

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1 EM 233, Fall 2016 Midterm #3 Ian R. Gould MPLETE TIS SETI : Up to TW PITS will be removed for incorrect/missing information! PRITED FIRST AME Answer Key Person on your LEFT (or Empty or Aisle) Person on your RIGT (or Empty or Aisle) lass you are REGISTERED FR (onground or hybrid) The room where most students will take the test for your class, i.e. LS A-191 for onground and PS -152 for hybrid) PRITED LAST AME **YU ARE T ALLWED T TAKE SPARE PIES F TIS EXAM FRM TE TESTIG RM** PRIT YUR AME EA PAGE! READ TE DIRETIS AREFULLY! USE BLAK PAGES AS SRAT PAPER work on blank pages will not be graded... WRITE LEARLY! MLEULAR MDELS ARE ALLWED D T USE RED IK D'T EAT, USE MM SESE! Li Be B F e a Mg e Al Si P S l Ar K a Sc Ti V r Mn Fe o i u Zn Ga Ge As Se Br Kr Rb Sr Y Zr b Mo Tc Ru Rh Pd Ag d In Sn Sb Te I s Ba Lu f Ta W Re s Ir Pt Au g Tl Pb Bi Po At Rn R 2 R (δ, ppm) variable and condition dependent, ca. 2-6 δ R R Aromatic R 2 R 2 Xe R 2 Aromatic Ar mainly R Interaction Energies, kcal/mol Eclipsing / ~1.0 /Me ~1. Me/Me ~2.6 Et/Et ~3.1 Infrared orrelation hart small range usually range of values strong broad peak peaks R 2200 broad with spikes ~ broad ~ broad ~ R (cm -1 ) 1500 MR orrelation harts 2 X R R 2 R Gauche Me/Me ~0.9 Et/Me ~0.95 i-pr/me ~1.1 t-bu/me ~2.7 Alkyl X Alkyl 3 > 2 > > 2 > 1 0 0

2 EM 233, Fall 2016 Midterm #3 Ian R. Gould YU MUST MPLETE TIS PAGE WIT YUR AME (EVE TUG YU ALREADY DID TIS TE VER PAGE) AD ALS GIVE YUR ASU R PSTIG ID UMBER WE EED TIS UMBER BEAUSE YU WULD'T BELIEVE TE UMBER F STUDETS WSE AMES WE A'T READ! PRITED FIRST AME ASWER PRITED LAST AME KEY ASU ID or Posting ID Points by question 1 /12 nomen nmr 2 /18 3 /3 mxn /35 reacts 5 /28 acids 6 /2 A/B eqm 7 /2 spec Points Removed for cover errors /2 Extra redit /5 Total (incl Extra) /175+5 **YU ARE T ALLWED T TAKE SPARE PIES F TIS EXAM FRM TE TESTIG RM**

3 EMISTRY 233, Fall 2016, Midterm #3-2 - AME Question 1 (12 pts.) Give the IUPA name for the following structure bromo-3-ethyl-2-methyl-(3Z)-heptene Br Question 2 (18 pts) For the proton nmr spectrum of the provided structure, circle the hydrogen atom or atoms that would have the smallest chemical shift, and also the hydrogen atom or atoms that would have the largest chemical shift, clearly indicate which is which. Give a BRIEF EXPLAATI that includes the term DESIELDIG. You will need to take into account a minor resonance contributor. Include a drawing of this minor resonance contributor in your answer. smallest largest the protons with the smallest chemical shift are least deshielded, they are farthest from the functional groups the proton with the largest chemical shift is deshielded as a result of being on the = bond, and the minor resonance contributors shows a partial positive charge on its carbon, which further deshields the proton

4 EMISTRY 233, Fall 2016 MIDTERM AME Question 3 (3 pts.) a) Give a curved arrow-pushing mechanism for the following reaction. Indicate the Lewis acid and base (LA, LB) for each intermolecular step, and whether they are also Bronsted acids and bases (BA, BB). Indicate the RATE DETERMIIG STEP for the mechanism. LB/BB 2 l (catalytic) rate detn step LA/BA LA LB LA/BA LB/BB b) Draw reaction energy diagram with properly labelled axes for the mechanism that you drew, Indicate the ATIVATI EERGY FR EA STEP, indicate the PSITIS F TE TRASI STATES FR EA STEP (but do T draw the transition states), indicate the REATI EXTERMIITY and the RATE DETERMIIG STEP Energy E a 1 E a 2 rate detn step E 3 a exothermicity E a reaction coordinate

5 EMISTRY 233, Fall 2016, MIDTERM AME Question (35 pts.) Give the missing major organic products R reagents/conditions as appropriate for each of the following reactions, include all non-bonding electrons. clearly indicate relative sterochemistry in the products where relevant a) 2 Pd/ b) Br 2 Br Br Br Br R c) 1. 2 /g(ac) 2 2. ab d) 1. B 3.TF 2. / 2 2 R e) Br Br l (inert solvent) Extra redit (5 pts) Dr. Gould had a conversation with his daughter about which topic? cisand transsaturated and unsaturated acids and bases Markovnikov and Anti-Markovnikov

6 EMISTRY 233, Fall 2016, MIDTERM AME Question 5 (28 pts.) For each structure A, B and, draw the conjugate base anion formed upon deprotonation of the indicated hydrogen atom, be sure to include ALL resonance structures where appropriate. Rank A, B and in order of increasing Brønsted acidity. Give a BRIEF explanation. A < < B A B weakest strongest deprotonation of gives a resonance stabilized anion with negative charges on and, which makes the most stable anion, deprotonation of B puts the negative charge on and which is thus higher in energy than that from, deprotonation of A gives an anion that is not resonance stabilized, thus highest in energy and thus its conjugate acid is the weakest Question 6 (2 pts) For the following Bronsted acid/base equilibrium a) add the curved arrow pushing for reaction in both directions b) indicate the strong and weak acid and base on each side and GIVE A EXPLAATI and DRAW RESAE TRIBUTRS AS APPRPRIATE c) indicate which reaction is faster and on which side the equilibrium lies d) indicate which acid has the smaller and which the larger pka weaker acid larger pka + weaker base slower faster + stronger base stronger acid smaller pka equilibrium on TIS side the base on the left is weaker because the electron energy is lower, the charge is delocalized onto the more electronegative oxygen, compared to nitrogen on the right

7 EMISTRY 233, Fall 2016 MIDTERM #3-6 - AME Question 7 (2 pts) Provided are spectra for a compound with molecular formula 10 1 a) Give the degrees of unsaturation b) n the infrared spectrum, indicate which peaks correspond to which functional groups (including (sp 3 )-). Indicate BT the functional group, and where appropriate, the specific BD 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 3 doublet no more peaks 3 triplet 3 5 unresolved splitting multiplet pentet 1 sextet