HEM3331: Fundamentals of rganic hemistry I Final Exam Prof. gnjen Š. Miljanić December 11, 2012 Name: Last First Student ID Number: ead all directions very carefully, think about your answer, and then write it legibly in the designated spaces. Total number of points is 390. 1. For each of the following reactions or series of reactions, draw the structure of the major product(s) in the box. Be sure to clearly indicate stereochemistry where this is pertinent. If you think that no reaction occurs, write "No eaction". 15 8 = 120 points F I N AL SE 1
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2. Give detailed mechanisms for the two reactions presented below. Show all charges and intermediates, and use curved arrows to indicate the flow of electrons. Do not draw transition states. 40 + 20 = 60 points 4
3. Name the following compound according to IUPA's systematic nomenclature. Indicate the stereochemistry of chiral centers and/or = double bonds where needed. 5 8 = 40 points 5
4. For each of the following two conversions, give a step-by-step outline of a synthetic sequence which would efficiently accomplish the required transformation. You may use any organic compound with two or less carbons, and any inorganic reagent. Do not give mechanisms. 2 30 = 60 points 6
5. Draw both chair conformations for the molecule shown below (D stands for deuterium, the heavier isotope of hydrogen). ircle the more stable conformation. Then, predict the product of E2 elimination of this precursor. Explain your reasoning in one brief sentence. 30 points HINT: does H or D get eliminated? 7
6. This question has several parts. In each segment, circle only one answer. 5 4 = 20 points ircle the strongest base among the following anions: S NH ircle the most electronegative element: Na B N Li Pb Hg ircle the most stable radical: ircle the only enyne among the following four compounds: Which compounds produce tertiary alcohols when reacted with Grignard reagents? alkanes aldehydes ketones alcohols ethers 8
7. Molecule A has molecular formula 8H 10. Its 1 H NM spectrum shows a doublet at 1.28 ppm (integrates for 6H), a quartet at 2.70 ppm (integrating for 2H), and a singlet integrating for 2H at 2.83 ppm. Its 13 NM spectrum contains four peaks, and its characteristic I bands are found at 2215 (weak), 2950, and 3300 cm 1. xymercuration of compound A produces compound B, which has molecular formula 8H 14 2. ompound B also has four peaks in its 13 NM spectrum, and its I spectrum is characterized by strong bands at 1725 and 2950 cm 1. 1 H NM spectrum of compound B shows a doublet at 1.11 ppm (integrating for 6H), a singlet at 1.98 ppm (integrating for 6H), and a quartet at 2.74 ppm which integrates form 2H.. Based on this information, draw the structures of compounds A and B in the provided boxes, and show your reasoning. 40 points 9
8. rder the three compounds A listed below by increasing acidity, and rationalize your answer using resonance structures. 30 points 10
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APPENDIES 1 H NM -H -NH 12 11 10 9 8 7 6 5 4 3 2 1 ppm 0 H H H--X Ar-H =-H H-- H--Ar H--N H--S H H 3 H 2 H X = an electronegative atom H--= H--= 1 H NM HAATEISTI HEMIAL SHIFTS / ppm methyl methylene methyne H 3 - -H 2 - H other 0.9 1.4 1.5 -H 1-5 1.6 2.3 2.6 2.1 2.4 2.5 -NH H H Ar-H 1-3 2.5 5.5 7.3 N -Ar Br l 2.2 2.5 2.9 2.3 2.7 3.0 2.7 3.3 4.1 3.1 3.4 4.1 H H 10 9-12 3.3 3.4 3.7
APPENDIES INFA-ED GUP ABSPTIN FEQUENIES TYPE F VIBATIN FEQUENY (cm -1 ) WAVELENGTH (µ) INTENSITY (1) H Alkanes (stretch) 3000-2850 3.33-3.51 s H 3 (bend) 1450 and 1375 6.90 and 7.27 m H 2 (bend) 1465 6.83 m Alkenes (stretch) 3100-3000 3.23-3.33 m (bend) 1700-1000 5.88-10.0 s Aromatics (stretch) 3150-3050 3.17-3.28 s (out-of-plane bend) 1000-700 10.0-14.3 s Alkyne (stretch) ca. 3300 ca.3.03 s Aldehyde 2900-2800 3.45-3.57 w 2800-2700 3.57-3.70 w Alkane not usually useful = Alkene 1680-1600 5.95-6.25 m-w Aromatic 1600-1400 6.25-7.14 m-w Alkyne 2250-2100 4.44-4.76 m-w = Aldehyde 1740-1720 5.75-5.81 s Ketone 1725-1705 5.80-5.87 s arboxylic acid 1725-1700 5.80-5.88 s Ester 1750-1730 5.71-5.78 s Amide 1700-1640 5.88-6.10 s Anhydride ca. 1810 ca. 5.52 s ca. 1760 ca. 5.68 s Acyl chloride 1800 5.55 s Alcohols, Ethers, Esters, arboxylic acids 1300-1000 7.69-10.0 s H Alcohols, Phenols Free 3650-3600 2.74-2.78 m H-Bonded 3400-3200 2.94-3.12 m arboxylic acids (2) 3300-2500 3.03-4.00 m N H Primary and secondary amines ca. 3500 ca. 2.86 m N Nitriles 2260-2240 4.42-4.46 m N= Nitro ( N 2 ) 1600-1500 6.25-6.67 s 1400-1300 7.14-7.69 s X Fluoride 1400-1000 7.14-10.0 s hloride 800-600 12.5-16.7 s Bromide, Iodide <600 >16.7 s (1) s = strong, m = medium and w = weak (2) note that the -H absorption of solid carboxylic acids which run as a nujol mull can be difficult to see as they maybe very broad
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