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Unformatted text preview: To pick up your graded exam from a box outside 5100A Pacific Hall sign here: ________________________
CHEMISTRY 140B FINAL EXAM SEPT 4,2004 NAME (please print)
FIRST LAST SIGNATURE
ID NUMBER LAST NAME OF PERSON SEATED ON YOUR RIGHT: LAST NAME OF PERSON SEATED OPN YOUR LEFT: - Please sign your name on the top of each page. - Please check to see that you have 10 pages (including this one). provided. Do not write answers on the back of a page. DO NOT OPEN THE EXAM UNTIL YOU ARE TOLD TO DO SO. Answer in the space Question Points Score _____________________________________ 1. 2. 3. 4. 5. 40 50 50 45 15 _____ _____ _____ _____ _____ _____________________________________ Total 200 _____ _____________________________________ H Li Na K Rb Cs Be B C Mg Al Si Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb N P As Sb Bi O S Se Te Po F Cl Br I At He Ne Ar Kr Xe Rn NAME:__________________________ 1a. (30 pts) Indicate whether each of the following statements are true or false by circling the correct answer. i) The following molecules contain an electrophilic oxygen atom: RCO3 H, O3 , H2 O, and OsO4 . True or False ii) The reactivity of the carbon-carbon double bond manifests itself in exothermic addition reactions leading to saturated products. True or False iii) Terminal alkynes are stronger acids than terminal alkenes due to the lower bond dissociation energy of the sp hypbridized C-H bond relative to the sp2 hybridized CH bond. True or False iv) Hydroboration-oxidation of terminal alkynes with dicyclohexylborane, (C6 H5 )2 BH, followed by treatment with hydroxide and hydrogen peroxide is a useful route toward aldehydes. True or False v) The reactivity of the carbonyl group increases with increasing electrophilic character of the carbonyl carbon. Therefore, aldehydes are more reactive than ketones. True or False vi) Alkylation of aldehydes usually fails because their enolates undergo a more favorable condensation reaction. True or False vii) The Diels-Alder reaction is a concerted stereospecific cycloaddition reaction of an scis diene to a dienophile. True or False viii) The elimination reaction with vicinal dihaloalkanes proceeds regioselectively and stereospecifically to give enols which rearrange to ketones by tautomerization. True or False ix) Hydrogenation of alkenes requires a catalyst because the reaction is otherwise endothermic. True or False x) Trisubstituted alkenes will undergo slower reactions than terminal alkenes with MCPBA because the more highly substituted the alkene the more thermodynamically stable it is. True or False 1b. (10 pts) The reaction of butadiene with HBr gives two products, A and B. When the reaction is run at 40C compound A is the major product, but when the reaction is run at 0C compound B is the major product. What are the structures of A and B? Circle the more thermodynamically more stable product. A B
2 NAME:__________________________ 2.
a) (50 pts) For each of the reactions shown below draw the structure of the major product(s). Where appropriate write "No Reaction". Show stereochemistry where appropriate. NO2 H3C Zn(Hg) HCl b) O CH3 Me O Cl AlCl3 c) SO3/ H2SO4 MeO Br d) O CH3 Br2 CH3CO2H e) CH3 Br2 NO2 FeBr3 3 NAME:__________________________ f) O HO TsOH g) O CF3CO3H h) H O Me 1. HCCLi 2. H3O+ i) O CH2CH=CH2 10% KOH EtOH Me j) O H 1) 2) EtBr NH 3) H+, H2O 4 NAME:__________________________ 3a. (25 pts) For each of the following one-step transformations show the movement of electrons by using the standard curved arrow notation. Show all formal charges for each structure to the left and to the right of the reaction arrow.
a) H I CH3 Me N Me Me C N H Me Me I b) O H O H O H O H c) H HO H H H O OH HO H O H H d) O C O H e) Li H O H CH2O Li 5 NAME:__________________________ 3b. (25 pts) In the boxes provided, give the reagent(s) need for each of the following transformations. More than one set of reagents may be necessary for a given transformation. a)
H H O O b) O c) O CH3 d) O Me C H e) Br CH2CH2OH 6 NAME:__________________________ 4a. (25 pts) In the boxes provided, draw the structure of the starting material need for each of the following transformations.
a) H+ - H2O
b) O O NaCN H+ NC OH c) O
Me Me TsOH O O d) AlBr3 e) OH Br2, H2O Br 7 NAME:__________________________ 4b. (20 pts) Ten compounds are shown below with a letter assigned to each. H NH2 N NH H N O A B C Me D
H C N N N F E G I H J List each compound that is aromatic by its letter designation: List each compound that is nonaromatic by its letter designation: List each compound that is antiaromatic by its letter designation: 8 NAME:__________________________ 5a. (15 pts) Provide an efficient synthesis for each of the following compounds from the indicated starting materials. Show all necessary reagents and give the structure of the product for each of the reactions that you employ. (a)
HO O O (b)
H2N 9 NAME:__________________________ (c)
O 10 ...
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This note was uploaded on 08/25/2009 for the course CHEM 140A taught by Professor Whiteshell during the Spring '04 term at UCSD.
- Spring '04