2005spring-midterm01a

2005spring-midterm01a - Chemistry 140C(Tor Spring 2005 1st...

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Unformatted text preview: Chemistry 140C (Tor) Spring 2005 - 1st Midterm Exam (V.1) This exam accounts for 20% of the final grade. Time 5:00 – 6:20 PM. Mark your final answer clearly and completely erase irrelevant information! Remember: Exams written in pencil will not be regraded! Additional pages are at the end for your convenience. Please indicate if your final answer should be found at the end of the exam. Good Luck! Your Name (Please Print): _____________________________ Your ID # : _____________________________ Question # 1: ..................................................................... /24 Question # 2: ..................................................................... /40 Question # 3: ..................................................................... /28 Question # 4: ..................................................................... /22 Question # 5: ..................................................................... /06 Total................................................................................... /120 1 Name: ________________________ ID# _________________ 04-19-05 1. Treatment of the chiral ketone 1 with 18O labeled water under acidic conditions gives a racemic mixture of the labeled ketones 2 and 3: . O H H218O, H318O+ 18O 18O H H 1 2 3 Write a detailed stepwise mechanism that accounts for the formation of 2 and 3. 2 Name: ________________________ ID# _________________ 04-19-05 2. For each one of the following reactions, circle the product that is formed. (a) O 1. [(CH3)2CH]2N 2. CH3I Li , 78 oC O O O (b) O H NaOH, H2O OH H O H O H (c) O OH O O O NaOH, H2O 50C HO O HO O (d) O O O O O O 1. CH3CH2O Na , CH3CH2OH, -5 oC 2. NaOH, H2O, O O 3 Name: ________________________ ID# _________________ 04-19-05 (e) CH3O O O CH3OH, H+ O O OCH3 HO O OCH3 O CH3O OCH3 (f) H2 N O NH O HCl, H2O, Δ OH O H 3N O Cl H3N OH O (g) O O O O O CO2H CN HCl, H2O, Δ CO2H CO2H O CO2H CO2H CO2H CO2H (h) CH3O O OCH3 O O O O CH3OH O HO O OCH3 O HO O OCH3 4 Name: ________________________ ID# _________________ 04-19-05 3. For each of the following pairs of compounds, decide which one is more acidic, and indicate it by using the symbol ">" (e.g., A>B for “A is more acidic than B”). Note: the H to be considered is highlighted. A O (a) H H H B O + (b) OH H + OH OH O (c) HO OH O O (d) H N(CH3)2 H O OH O Cl O (e) F OH F O OH O OH Cl O OH (f) O (g) OH O OH 5 Name: ________________________ ID# _________________ 04-19-05 4. Treatment of ester 4 with dilute aqueous acid leads to the formation of ester 5: a) Write a detailed stepwise mechanism that accounts for the formation of product 5. (Show all intermediates! Transfer H’s intermolecularly!). b) Why is the formation of 5 preferred? Explain using resonance structures and two sentences only. 6 Name: ________________________ ID# _________________ 04-19-05 5. Dissolving an aldehyde in water leads to an equilibrium mixture of the aldehyde and its hydrate as shown below: O . H 2O R H KHyd HO R OH . H (a) Rank the relative magnitude of KHyd for the following three aldehydes (1 being the largest KHyd and 3 being the smallest KHyd): O . O Cl H H Cl Cl O . Cl H (b) Explain in one sentence only your answer to question a. 7 ...
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This note was uploaded on 04/14/2009 for the course CHEM140C 234234 taught by Professor Nefzi during the Spring '09 term at UCSD.

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