CHEM 234, Spring 2009 Second Midterm Ian R. Gould PRINTED PRINTED ASU ID or FIRST NAME LAST NAME Posting ID Person on your LEFT (or Aisle) Person on your RIGHT (or Aisle) 1__________/10.........................9_________/8............................ •!PRINT YOUR NAME ON EACH PAGE! 2__________/10........................10_________/12......................... • READ THE DIRECTIONS CAREFULLY! 3__________/9..........................11_________/12......................... • USE BLANK PAGES AS SCRATCH PAPER 4__________/9..........................12_________/25......................... work on blank pages will not be graded... 5__________/18 ......................... •WRITE CLEARLY! 6__________/25......................... • MOLECULAR MODELS ARE ALLOWED 7__________/25......................... • DO NOT USE RED INK 8__________/12......................... • DON'T CHEAT, USE COMMON SENSE! Extra Credit_____/5 Total (incl Extra)________/175+5 H He Interaction Energies, kcal/mol Li Be B C N O F Ne Eclipsing Gauche Na Mg Al Si P S Cl Ar H/H ~1.0 Me/Me ~0.9 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr H/Me ~1.4 Et/Me ~0.95 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Me/Me ~2.6 i-Pr/Me ~1.1 Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Me/Et ~2.9 t-Bu/Me ~2.7 Infrared Correlation Chart Approximate Coupling small range O H C N usually Constants, J (Hz), for range of values strong 1 N H C O C H NMR Spectra broad peak C C 1600–1660 N C H O H H H O C C ~7 C H 3300 C H 2720–2820 C N O 3000– 2 peaks H H H 3100 N H C 1680 C C ~10 2200 OR ~8 C H H broad with spikes ~3300 1735 H C CH 2850–2960 O 1600 C C ~2 H O H C O O H broad ~3300 2200 ~2 C O H C H 1710 H NR2 ~15 broad ~3000 1650 C C (cm-1) 3500 3000 2500 2000 1500 H O amine R NH2 variable and condition NMR Correlation Charts –OCH2– alcohol R OH dependent, ca. 2 - 6 ! C CH3 –H2C X O Aromatic Ar H –H2C NR2 O C H mainly 8 - 6.5 Alkyl C CH R C OH 2 C CH 3Y > 2Y > 1Y 11 10 9 8 7 6 5 4 3 2 1 0 (!, ppm) 220 O 200 180 160 140 120 100 80 60 40 20 0 R C N –OCH – R C OH 2 O Alkyl 3Y > 2Y > 1Y R C CR C 2 2 RC CR C X Aromatic C NR2 - 2 - CHEMISTRY 234, Spring 2009 MIDTERM #2 NAME Question 1 (10 pts.) Give the IUPAC name for the following compound. Be sure to use cis/trans, E/Z or R/S where appropriate. OEt OH Question 2 (10 pts) Indicate which of the following two reactions, A or B would be faster. GIVE AN EXPLANATION THAT INCLUDES A DISCUSSION OF THE EXOTHERMICITY OR ENDOTHERMICITIES OF THE REACTIONS (only 1 point for the correct answer, 9 pts for the explanation) MeOH A Br + Br– heat MeOH B Br + Br– heat - 3 - CHEMISTRY 234, Spring 2009 MIDTERM #2 NAME Question 3 (9 pts) Give the product of the following Diels-Alder reaction. Indicate both the relative and the absolute stereochemistry CN heat + NMe2 Qestion 4 (9 pts) Give the diene and dienophile that react to give the provided structure in a Diels-Alder reaction OMe CF heat 3 (±) Extra Credit Question (5 pts.) In which kind of biomolecule can a photochemical 2 + 2 cycloaddition reaction take place DNA phospholipid carbohydrate protein - 4 - CHEMISTRY 234, Spring 2009 MIDTERM #2 NAME Question 5 (18 pts.) For the following reactions, provide the missing MAJOR REACTION PRODUCT. Indicate stereochemistry where appropriate. 1 Equiv Me–MgBr a) Br Br O Na+ –OEt Ph b) EtOH Ph Question 6 (25 pts.) For the following reaction, give a full curved-arrow pushing mechanism for formation of BOTH 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 reasonable resonance contributors for any intermediates OMe HBr MeO + MeOH (solvent) A B b) Indicate which is the thermodynamically controlled product and which the kinetically controlled product, and state which would be more likely to be formed at HIGHER temperature. Give a BRIEF explanation - 5 - CHEMISTRY 234, Spring 2009 MIDTERM #2 NAME Question 7 (25 pts.) Show how you would make the target compond on the right from the starting compound on the left. Show reagents and conditions where appropriate, and the structures of important intermediate compounds. Do not show any (arrow pushing) mechanisms. CN CN Question 8 (12 pts) a) Give the curved arrow-pushing and the allowed product for the following cycloaddition reaction. Be sure to indicate both relative and absolute stereochemistry. H H C CN heat O + O NC b) How many !-electrons are involved in the reaction that you drew? __________ c) For the number of electrons that are involved in YOUR reaction, is a Huckel or a Mobius transition state allowed? ______________________________ d) Explain WHY a Huckel/Mobius transition state (as appropriate) is allowed in YOUR reaction. Include a discussion of the energies of the electrons in the transition state in your explanation. CHEMISTRY 234, Spring 2009 MIDTERM #2 - 6 - NAME Question 9 (8 pts) a) Give the curved arrow-pushing for the following electrocyclic ring opening reaction heat b) Did THE REACTION SHOWN (which is not necessarily an alowed reaction) proceed via a conrotatory or a disrotatory ring closure? ______________________________ c) Did THE REACTION SHOWN (which is not necessarily an alowed reaction) proceed via a Huckel or a Mobius transition state? ______________________________ d) Is THE REACTION SHOWN allowed or forbidden? ______________________________ Question 10 (12 pts) a) Give the curved arrow-pushing and the allowed product for the following electrocyclic ring closure reaction heat b) ON TOP OF THE STRUCTURE, draw the HOMO of the reactant cation c) To form YOUR product, did the reaction proceed via a conrotatory or a disrotatory ring opening? ______________________________ Question 11 (12 pts.) a) Give the curved arrow-pushing for the following cycloaddition reaction heat + Ph Ph B A b) ON TOP OF THE STRUCTURES, draw the LUMO for A the HOMO for B c) FOR THE PROVIDED PRODUCT (which may or not be the allowed product), was the reaction suprafacial with respect to reactant A? (Y/N) _____________ d) FOR THE PROVIDED PRODUCT (which may or not be the allowed product), was the reaction suprafacial with respect to reactant B? (Y/N) _____________ e) Is the REACTION SHOWN allowed or forbidden? _____________ - 7 - CHM 234, Spring 2009, Midterm #2 NAME Question 7 (25 pts) Provided are spectra for a compound with molecular formula C5H10O a) Give the degrees of unsaturation ________________ b) On the infrared spectrum, indicate which peaks correspond to which functional groups 3412 3392 1110 776 997 1452 2899 2981 1198 1376 2991 1706 c) draw the structure and clearly indicate which hydrogens correspond to which signals in the proton nmr spectrum (only) 3H triplet 3H singlet 2H 2H sextet triplet .