sum06 midterm1 key

Sum06 midterm1 key - CHEMISTRY 30B UCLA SUMMER SESSION C 2006 MIDTERM EXAM I KEY On my honor I have neither given nor received any aid on this exam

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Unformatted text preview: CHEMISTRY 30B UCLA SUMMER SESSION C 2006 MIDTERM EXAM I KEY On my honor, I have neither given nor received any aid on this exam. Wag Signature I. D. Number Key Circle the Name of Your TA Name (Print) Juan Fernandez Rebecca Lui Alex Tucker—Schwartz Question Points Chemistry 308, Summer 2006 Name: Key Page 2 THEORY l. A. (6) A very important physical property that medicinal chemists must consider when designing new pharmaceutical agents is the water solubility. Explain how add1ng alcohol and ether groups to a molecule will increase its water solubility. Ether lgrogps can be HYDROGEN BOND ACCEPTORS from water and the DIPO E OMENT adds polarization that im roves solub111ty 1n water. ThlS later effect is much smaller than the hydrogen bon mg, but still important. Alcohol groups are both HYDROGEN BOND ACCEPT ORS AND DONORS with water and the DIPOLE MOMENT also adds polarization that improves solubility in water. B. (6) What are the approximate pKa’s of the following compounds? Propanol Water Propanoic acid Propanethiol Propyne 16 16 5 9 25 C. (2) Based on the IR adsorption frequencies, which bond is stronger: C=C or C=O? The stretching frequencies for typical carbonyl groups are at higher energies (1650—18000m‘1) than those for alkenes (1600—1680 cm"), so the C=O bond is stronger. D. (6) A bottle of colorless liquid smells like it might be l—hexyne, or 3—hexyne. Explain in detail how you would use IR spectroscopy to identify it. The IR spectrum for 1—hexyne would have alkane C—H stretching adsorptions at 3000—2900 cm", a C—H stretching signal at 3300 cm“, and CC at about 2150 cm'] in addition to signals <1500 cm‘1 in the fingerprint region. The IR spectrum for 3—hexyne would have alkane C—H stretching adsorptions at 3000—2900 cm"and the signals <1500 cm'1 in the fingerprint region. There is no C—H stretching signal above 3000 cm‘1 and the CC adsorption is absent since the bond has no dipole moment due to the symmetry. Chemistry 308, Summer 2006 Name: Key Page 3 MECHANISMS 2. (10) Propose a detailed mechanism for the following reaction. 0L3 HCI EtOH OioA H+ 0% car) Chemistry 30B, Summer 2006 Name: Key Page 4 REACTIONS 3. (18) Draw the products for the following reactions. Pay Attention to Stereochemistry. A. 9” soong Pyr 9| B. >0 1)MCPBA CHZCIZ >60“ 2) NaOH H20 "IOH C, 1)OsO4 H20 OMe >0 2)2eq NaH ><I Zeq Mel DMSO OMe D. OH O OH PCC CHQCI2 O HO H WOH E. 1)TsC| Pyr <:>‘S S—<:> ""'<:>"'OH 2)NaSH DMF 3) 02 F. 1 NaH B -I THF H V 7/ SH ) u 2) NaIO4 MeOH ; ; O warm Chemistry 308, Summer 2006 Name: Key Page 5 REACTIONS 4. (18) Propose reactions for the following transformations. Pay Attention to Stereochemistry. A. OH HBr Br B. /\/ OH NaH EtI DMF O 3 OR: EtOH cat. H2804 C C. 1)H3PO4 H2804 heat 0 0“ 2a) 03 CH2C12 b) M928 H 0 OP OR:2)OSO4 H20 3) Na|O4 MeOH D. 9H 1)Ts—C| pyr w M 2) NaH DMF Hoar E. s/\ 1)MCPBA CHQCIZ - W /Y\/ 2) EtSH NaH DMSO OH F. 0 w 1) 0804 H20 2) cat. H2804 Chemistry 30B, Summer 2006 Name: Key Page 6 SYNTHESIS 5. (l8) Propose reactions for the following transformations. Pay Attention to Stereochemistry. A. 1)TBDMS—C| Pyr 0 2a) BH3 THF b) H202 NaOH H20 HO / HO OH 3)HQCrO4 acetone H20 4) Bu4NF THF B. O 1) MCPBA CHgClg (ION 2) NaCN DMF O 3) PCC CH2C|2 C. AJJV 1)L-(+)-DET Ti(OiPr)4 t-BUOOH OH 2) 2 eq HCC-iPr 2 eq BuLi THF 3) P00 CHZCIQ One enantiomer Note: Could avoid using 2 equivalents of acetylide anion by protecting alcohol. Chemistry 303, Summer 2006 Name: Key Page 7 6. Infrared Spectroscopy A. (6) The molecular formula for an unknown material as determined by mass spectrometry is C6l~ll lNO. Calculate the number of Double Bond Equivalents. SHOW YOUR WORK. DBE=#C—#H/2+#N/2+1= 6—11/2+1/2+1=2 B. (6) The IR spectrum is below. What are the most likely functional groups present? C—H Stretching <3000 cm" therefore alkane N—H Stretches (2!) at 3350 and 3200 cm" therefore NH2 C=O Stretches at 1600 and 1650 cm"1 therefore NH2 amide N0 C—O Stretch Mlcnons a to 11 12 13 14 15 1o 11 11 m 2.2 273 aid 2.5 216‘ 2:1 2.8 2]!!! I]! Y ‘315 I lv Y4i5 r I V 55 if V I7 v M? '7’ l: _ 1‘ 7 .1 V . . . 7, 7. Y I, n 1 - , i . , ,,, ‘ ‘ 1 \ R , g { . . g I I) VT. E. 1r... ‘. f, .1 . , .I .. .,; .. . .; ‘3 ..: . . . , g 1 ‘ = 1 s 1 1 ‘ I 1 4 z = 5 a I i "3. L i P1“; . , ‘ 1 ,l.. .. a ‘ i 2 I 1 - f 3 1 7D ‘ ‘ V. a . r l . ‘3"; y 1 I. .ll .l l 1 iv 2 : I l 50 Ii, 4. g. u 1 , t , . ,g . i l " - f a I i . 1: 40‘1"“, , i .5 .1 s i, i l * ‘ 3 ~ 1 h... v‘ l . 3 l . ‘ will! 4 -5 J l -- 7:» 1f! . 1 v i y E g t : NV‘t 17 l «4 l i ( 1 l l 1 i ; . 10‘» w 2. v,.,, ‘, 1 ‘ 1 t . ‘ 1 > . . t 01 .1 1 ,i.‘ .. . 1. « l.‘ .. l2. l,.‘,,|, ., 1,. . . : , H I : muwammaammmmmzmmmm 2001: mm 1600 1400 1200 1000 coo coo WAVENUMBERS NICC C. (8) CIRCLE the structure that is the most likely for the unknown compound. 0 H OH H N O < >/ N— H 2 \ /N H ...
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This test prep was uploaded on 04/06/2008 for the course CHEM 30B taught by Professor Rubin during the Summer '05 term at UCLA.

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Sum06 midterm1 key - CHEMISTRY 30B UCLA SUMMER SESSION C 2006 MIDTERM EXAM I KEY On my honor I have neither given nor received any aid on this exam

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