Organic Chemistry I

Lecture063719s18.notebook 1 January 25, 2018 Jan 255:04 PM Lecture063719s18.notebook 2 January 25, 2018 Jan 255:15 PM Lecture063719s18.notebook 3 January 25, 2018 Jan 255:22 PM Lecture063719s18.notebook 4 January 25, 2018 Jan 255:34 PM Lecture063719s18.notebook 5 January 25, 2018 Jan 255:40 PM Lecture063719s18.notebook 6 January 25, 2018 Jan 255:48 PM Lecture063719s18.notebook 7 January 25, 2018 Jan 255:56 PM Lecture063719s18.notebook 8 January 25, 2018 Jan 256:04 PM Lecture063719s18.notebook 9 January 25, 2018 Jan 256:10 PM Lecture063719s18.notebook 10 January 25, 2018 Jan 256:15 PM Lecture063719s18.notebook 11 January 25, 2018 Jan 256:20 PM

CHEM | 3719 | Organic Chemistry I | study guides | Lecture063719s18.notebook 1 

Lecture043719s18.notebook 1 January 18, 2018 Lecture043719s18.notebook 2 January 18, 2018 Lecture043719s18.notebook 3 January 18, 2018 Lecture043719s18.notebook 4 January 18, 2018 Lecture043719s18.notebook 5 January 18, 2018 Lecture043719s18.notebook 6 January 18, 2018 Lecture043719s18.notebook 7 January 18, 2018 Lecture043719s18.notebook 8 January 18, 2018 Lecture043719s18.notebook 9 January 18, 2018 Lecture043719s18.notebook 10 January 18, 2018

CHEM | 3719 | Organic Chemistry I | study guides | Lecture043719s18.notebook 1 

CHEM 3719 – Exam 2 – March 16, 2017 – Student Number 00__________NAME_________________ 1 1. (10 pts). Assign the absolute stereochemistry [( R ) or ( S )] of any 5 chiral centers ( your choice ) in 21-hydroxyoligomycin A. Choose only 5 chiral centers , or you will have points deducted for incorrect answers. O O O OH O OH OH HO OH O O OH 4 5 6 8 9 10 12 13 14 20 21 23 24 25 26 27 30 31 33 J. Nat. Prod. 2007 , 70 , 367-371. 4 ( S ), 5 ( R ), 6 ( S ), 8 ( R ), 9 ( R ), 10 ( S ), 12 ( R ), 13 ( S ), 14 ( R ), 20 ( S ), 21 ( R ), 23 ( S ), 24 ( R ), 25 ( R ), 26 ( S ), 27 ( R ), 30 ( S ), 31 ( S ), 33 ( R ). CHEM 3719 – Exam 2 – March 16, 2017 – Student Number 00__________NAME_________________ 2 2. (10 pts). Provide a complete, step by step mechanism for the following transformation. Draw the structures of all intermediates formed in the mechanism. Use arrows to show "pushing" of electrons. + H 2 O Cl HCl (±) OH OH H Cl OH 2 -H 2 O H Cl Cl 1,2-hydride shift 3. (10 pts). Provide a complete, step by step mechanism for the following transformation. Draw the structures of all intermediates formed in the mechanism. Use arrows to show "pushing" of electrons. (±) OCH 3 CH 3 OH Cl Cl 1 2 3 4 5 1 2 3 4 5 CH 3 OH O H CH 3 CH 3 OH OCH 3 3 o carbocation strained ring 2 o carbocation more stable ring CHEM 3719 – Exam 2 – March 16, 2017 – Student Number 00__________NAME_________________ 3 4. (10 pts.) Given the reaction of ethylene glycol with a catalytic amount of sulfuric acid to form 1,4- dioxane: provide the Missing Arrows in the reaction mechanism below : H 2 O or ROH H 2 O or ROH -H + acid-base acid-base acid-base acid-base S N 2 S N 2 "H + " -H + "H + " O O O O H HO O OH 2 HO O OH HO O OH H HO OH HO OH 2 HO OH + 2 H 2 O 2 eq. heat H 2 SO 4 (cat) HO OH O O 1,4-dioxane ethylene glycol CHEM 3719 – Exam 2 – March 16, 2017 – Student Number 00__________NAME_________________ 4 5. (10 pts) Draw both chair forms of each of the following. Indicate which of the four chair forms is the MOST STABLE. i -Pr H i -Pr H H i -Pr H i -Pr i -Pr H H i -Pr H i -Pr i -Pr H MOST STABLE 6. (5 pts.) Calculate the Heat of Reaction ( ∆ H o ) for the formation of bromoethane from reaction of ethane with bromine. Bond energies: H-CH 2 CH 3 (98 kcal/mole), Br-Br (46 kcal/mole), CH 3 CH 2 -Br (81 kcal/mole), H-Br (88 kcal.mole). CH 3 CH 3 + Br 2 CH 3 CH 2 Br + HBr Break C-H +98 kcal/mole, break Br-Br + 46 kcal/mole, form C-Br -81 kcal/mole, form HBr -88 kcal/mole NET = -25 kcal/mole 7. (5 pts) Draw the structure of the Transition State (the high energy intermediate) that would occur during the reaction of 1-chloropropane with sodium cyanide in DMSO. DM SO Cl NaCN CN C NC Cl Et H H δ δ =

CHEM | 3719 | Organic Chemistry I | exam | CHEM 3719 – Exam 2 – March 16 

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