Unformatted text preview: EXAM 2 CHEMISTRY 241b March 11, 2004 Dr. Spurgeon Answer Key
__________________________________________________________________________________________ 1. (8 points) Provide either the IUPAC name or structural formula for the following: a. o-(2-Hydroxyethyl)phenol
OH OH b. 2-(1-Chloroethyl)-5-methylheptanal
Cl H CH3 O O c.
O O 3,5-octadienal Name______________________________________ 2,4-hexadione Name______________________________________ 2. (6 points) For each group, circle the acid with the lower pKa:
CO2 H or
CO2 H NO2 HCOOH or CH3COOH or CF3COOH CH3COOH or CH3CH2COOH or CH3CH2CH2COOH 3. (15 points) You know how amines react with a,b-unsaturated carbonyls but maybe you didn't know that they also react with esters in the following way: RCO2R' + R"NH2 RCONHR" + R'OH Propose a mechanism for the following reaction of an a,b-unsaturated ester:
O OCH3 CH3 N O + CH3NH2 H3C + CH3OH O OCH3 CO2 CH3 H+ trans. O NH2CH3 OCH3 CH3 HN O OCH3 H+ trans. tautomerization
O OCH3 O OCH3 4. (10 points) Identify the reagents, a-e, in the following reaction scheme:
OH O CH3
CH3 a CH3 b d
O a CH3MgBr then H3O+ b POCl3, pyr. or H3O , heat
CH3 OH CH3 c Hg(OAc)2, CH3OH; then NaBH4 d MCPBA e H3O+ OH 5. (6 points) Provide the structural formula for the acetal that would result when the following reactions take place:
O a. O b.
OH HO OH H HO cat. H+ cat. H+ O O
O O 6. (33 points) Complete the following reaction schemes by filling in the boxes with the appropriate starting material, reagent(s), and/or product.
HO 1. CNO O 2. H3O+
OH 1. Ph3P Ph3P=CH2 2. n-BuLi CH3Br OH CH3 1. Hg(OAc)2, H2O, H+ 2. NaBH4 CH2 1. BH3, H2O2, OH-, H2O
BH3, H2O2, OH-, H2O
OH POCl3, pyr. 2. Any Cr(VI) reagent (except PCC) Also Ag2O, NH4OH works
O 1. O3 2. DMS
O O OH H 7. (26 points) Provide a reasonable synthesis to prepare the following molecules. You must start with the staring material shown but you may use any other organic or inorganic reagent. Once the compound is prepared then complete the subsequent reaction scheme. O
O Br a. 1. (Me)2CuLi 2. CH3I 3. Work-up CH3 CH3 O Br COOH COCl 1, Mg 2. CO2 3. H3O+ SOCl2 pyr. 2 CuLi THF -78oC O b. MCPBA BH3 H2O2, OHH2O OH PCC CH2Cl2
H O Ph3P=CHCH2CH3 ...
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- Spring '05
- pH, Carboxylic acid, following reaction, Methane