HEM 234, Spring 2017 Midterm #2 Ian R. Gould MPLETE THIS SETIN : Up to TW PINTS will be removed for incorrect/missing information! PRINTED FIRST NAME PRINTED LAST NAME Person on your LEFT (or Empty or Aisle) Person on your RIGHT (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 H-152 for hybrid) **YU ARE NT ALLWED T TAKE SPARE PIES F THIS EXAM FRM THE TESTING RM** PRINT YUR NAME N EAH PAGE! READ THE DIRETINS AREFULLY! USE BLANK PAGES AS SRATH PAPER work on blank pages will not be graded... WRITE LEARLY! MLEULAR MDELS ARE ALLWED D NT USE RED INK DN'T HEAT, USE MMN SENSE! H Li Be B N F Ne Na Mg He Al Si P S l Ar K a Sc Ti V r Mn Fe o Ni u Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag d In Sn Sb Te I s Ba Lu Hf Ta W Re s Ir Pt Au Hg Tl Pb Bi Po At Rn R NH 2 R H (δ, ppm) variable and condition dependent, ca. 2-6 δ R 11 220 R H 10 200 H H 9 180 8 160 7 140 Aromatic R 2 R 2 Xe 6 5 120 100 R N H 2 Aromatic Ar H mainly 8-6.5 H 2 4 80 R Interaction Energies, kcal/mol Eclipsing H/H ~1.0 H/Me ~1.4 Me/Me ~2.6 Et/Et ~3.1 H N Infrared orrelation hart small range usually range of values strong N H broad peak 1600 1660 H N H H 3300 H N 2720 2820 N H 3000 2 peaks 3100 1680 R H 2200 broad with spikes ~3300 1735 2850 2960 H H 1600 broad ~3300 H 2200 broad ~3000 1710 NR2 3500 3000 2500 2000 1650 (cm -1 ) 1500 NMR orrelation harts H 2 X R 3 60 H 2 H 3 H 2 NR 2 H NR 2 2 40 Gauche Me/Me ~0.9 Et/Me ~0.95 i-pr/me ~1.1 t-bu/me ~2.7 Alkyl X Alkyl 3 > 2 > 1 1 20 3 > 2 > 1 0 0
HEM 234, Fall 2017 Midterm #2 Ian R. Gould YU MUST MPLETE THIS PAGE WITH YUR NAME (EVEN THUGH YU ALREADY DID THIS N THE VER PAGE) AND ALS GIVE YUR ASU R PSTING ID NUMBER WE NEED THIS NUMBER BEAUSE YU WULDN'T BELIEVE THE NUMBER F STUDENTS WHSE NAMES WE AN'T READ! PRINTED FIRST NAME PRINTED LAST NAME ASU ID or Posting ID Points by question 1 /11 2 /24 3 /24 4 /22 5 /38 6 /20 7 /14 8 /22 Points Removed for cover errors /2 Extra redit /5 Total (incl Extra) /175+5 **YU ARE NT ALLWED T TAKE SPARE PIES F THIS EXAM FRM THE TESTING RM**
HEMISTRY 234, Spring 2017 MIDTERM #2-2 - NAME Question 1 (11 pts.) Give the IUPA name for the following compound. Be sure to use cis/trans, E/Z or R/S where appropriate. Question 2 (24 pts) Give a curved-arrow pushing mechanism for the following reaction. Where appropriate, indicate the Lewis acid and base (LA, BA) and the Bronsted acid and base (BA, BB). conc. HBr Br Br + H 2 heat Extra redit (5 pts) The colors of organic molecules are determined to a large extent by the energies of electrons in? sigma-bonding orbitals anti-bonding orbitals atomic orbitals
HEMISTRY 234, Spring 2017 MIDTERM #2-3 - NAME Question 3 (24 pts) Give the major organic products of the following reactions, indicate the stereochemistry using wedged/dashed bonds as appropriate. State whether the products are achiral, a racemic mixture, meso or a single enantiomer (no explanation needed) a) EtH/Hl (cat.) b) 1. MPBA 2. Na + Et/EtH N c) + heat N Question 4 (22 pts) a) Give the curved arrow-pushing and the allowed product for the following electrocyclic ring closure reaction, indicate whether the product would be achiral, a meso compound or a racemic mixture heat b) How many electrons are involved in the reaction? c) Does the allowed reaction proceed via a Huckel or a Mobius transition state? d) Does the allowed reaction proceed via a conrotatory or disrotatory ring opening? e) If you said that the reaction proceeds via a Huckel transition state then VERY BRIEFLY explain why it doesn't go via a Mobius transition state, or if you said Mobius then why not Huckel? Your explanation should include the terms "aromatic" or "anti-aromatic" as appripriate
HEMISTRY 234, Spring 2017 MIDTERM #2-4 - NAME Question 5 (38 pts.) For the following reaction, give a full curved-arrow pushing mechanism for formation of BTH products and indicate the Lewis acid and base at each step (LA or LB) and whether they are also Bronsted acids and bases (BA or BB), include all important resonance contributors for any intermediates and give the number of STEPS for each reaction. The curved arrow-pushing for the first step is provided for you. Me LB/BB MeH (solvent) Me H + Me Hl (cat.) A B H LA/BA number of steps in the mechanism for product A number of steps in the mechanism for product B b) Draw a reaction energy diagram for formation of BTH of these products on the same diagram, you do not have to include any structures on your diagrams, but LEARLY INDIATE WHIH DIAGRAM REFERS T WHIH REATIN, and INDIATE the positions of all TRANSITIN states c) Briefly explain which product is more likely to be formed under conditions of kinetic and thermodynamic control, and why
HEMISTRY 234, Spring 2017 MIDTERM #2-5 - NAME Question 6 (20 pts.) Show how you would make the target componds on the right from the starting compounds on the left. Show reagents and conditions where appropriate, and the structures of important intermediate compounds. Do not show any (arrow pushing) mechanisms. H Ph (±) Question 7 (14 pts.) a) For the provided structure, show you you would make the bond A in a Grignard reaction, give the Grignard reagent, what it would react with and any other reagents/conditions b) BRIEFLY explain why you can't make bond B in a Grignard reaction bond B bond A H (ignore stereochemistry)
HEMISTRY 234, Spring 2017 MIDTERM #2-6 - Question 8 (22 pts.) a) For the cycloaddition reaction shown below... NAME Me + heat A B a) Give the curved arrow-pushing and draw the allowed product for the reaction, be sure to include stereochemistry and indicate any racemic mixtures b) on TP of reactant A draw a pictorial representation of the HM (draw it on the structure below rather than the one in the equation so that the curved arrow-pushing isn't obscured) Me c) on TP of reactant B draw a pictorial representation of the LUM (draw it on the structure below rather than the one in the equation so that the curved arrow-pushing isn't obscured) d) Is the allowed reaction suprafacial or antarafacial for reactant A? e) Is the allowed reaction suprafacial or antarafacial for reactant B?