Exam 4 Key

Exam 4 Key - NAME last, first 810# CHEMISTRY 2211 EXAM 4...

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Unformatted text preview: NAME last, first 810# CHEMISTRY 2211 EXAM 4 April 27, 2011 Be sure to read each question carefully. Partial credit will be assigned where appropriate. Onl answers written in the boxes or on the lines will be raded. SCORE 1 (18 points) Draw the structure of the major organic product(s) for each of the 1‘ following reactions. Indicate the stereochemistry for each reaction when appropriate. 2. Br ,6, H H / CN —_ NaCN /, ’"—.> / 3. polar aprotlc #— solvent CH3OH —————-> Br HCl ———> H36 OH NaSH C(CH3)3 ————.> Br polar aprotic solvent CH(CH3)2 KOH heat Cl CH3 CHZONa H3C \Br -——-—> os‘ ethanol ————-- PBI'3 ether / \\\\\\ Y H OH V ’13 2 . (15 points) Predict the major product (or products) resulting from reaction of (1R,3R)-1- bromo-3-methylcyclohexane with a) iodide ion DMSO; b) water; 0) acetlylide ion in THF. In chiral products, use R, S notations to label all chirality centers. (9 1 /DMSO H20 (4 points) Complete the following reactions. OH CHgCHZMgBr EtzO CI NAME 3 last, first 8 1 0# 3. (20 points) Treatment of benzyl bromide with either CH3O' or CH3OH yields the same product. When CH3O' is used, the rate of product formation depends on the concentration of CH30', but when CH3OH is used the rate of product formation does not depend on the concentration of CH3OH. Br benzyl bromide Label the reaction as SN2, SNl, E2 or BI. Show the reaction mechanism for the reaction of benzyl bromide with CH3O', including the transition state(s) or intermediate(s), and use your mechanism to explain the dependence of the reaction rate on the concentration of CH30' . Vizmouaqowm Kama “we: 1 QUKQTMWTIE 117w; NUCLEOFHiu-E Rflfi IN RflTélDETERfiMNlN& ‘ETEF Label the reaction as 8N2, SNl, E2 or E1. Show the reaction mechanism for the reaction of benzyl bromide with CH3OH, including the transition state(s) or intermediate(s), and use your mechanism to explain why the reaction rate is independent of the concentration of CH3OH. G? /’— P SLOML TE gram/“w wt: crev- I UN/MDLEcuLHK KINETng . gumsTrL/‘WE IS @NO/ THE ' (A! THE RATE Denimnmmb s71; ra 4 4. (12 points) Ethers can often be prepared by 8N2 reaction of alkoxide ions, RO-, with alkyl halides. Suppose you wanted to prepare cyclohexyl methyl ether. Choose the route below that will give the desired product and show its mechanism. 0 + CH3I OCH3 OR —> I + CH3O' Mechanism: Draw the structure of the expected product formed by reaction of the other alkyl halide and alkoxide pair. By what mechanism does it form? Mechanism E Z NAME 5 last, first 8 1 0# 5. (12 points) Below are the spectra of two symmetrical tertiary amines (R3N). In the boxes provided, draw the structure of the amine and the most abundant alpha cleavage fragment. 100 "swam Amine Structure 80 / u \ C.chch . ‘H CH N9 3 (D 0 Relative Intensity A 0 Alpha Cleavage Fragment 2° .0 4... / &' CHLCHLflHg 0 CH; CH;CH1CH3 25 50 75 100 125 150 175 100 Amine Structure 8° N / g“ (Ll-la, CmH’g at 0 Relative Intensity A 0 Alpha Cleavage Fragment VB " ' 20 +5 I CH2. ems-t 5,43 10 20 30 40 50 60 70 80 90 100 6 6. (20 points) Consider the following radical chlorination reaction. Draw all possible monochlorination substitution products in the boxes provided and give the estimated percentage of each product you expect to obtain. (Note: there may be more boxes provided than possible products. Ignore stereoisomers. C1: 1° = 1.0; 2° = 3.6; 3° = 5.0) C12, I’lV NAME 7 last, first 810# 7. (8 points) Draw structures for the products of the following bromination reaction. In the inset box, draw the structure for the key resonance hybrid intermediate that determines the regiochemistry of the products. NBS, hv, CC14 —-——-> Bromination products 4—» ...
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Exam 4 Key - NAME last, first 810# CHEMISTRY 2211 EXAM 4...

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