University:
Amherst College
Course:
CHEM 221 | Organic Chemistry I
Academic year:

2024
Views:

34

Pages:

6
Author:

Rafael Werner

/h L V o L Exam 4 Chem 22 April 22, 2010 Name page 6« ^ 1 (20) 2 (35 ) total (200) 3 (40) chk 4 (40) 5 (35) 6 (35) Please resist the temptation to deface this space. . 1 (20 points) (a) Draw the most stable enol tautomer ( if any ) of each carbonyl compound below. o _ 2 Cf a} TM Co* \ ) (b) Rank the carbonyl compounds above according to the amount of enol present at equilibrium, with 1 indicating the most enol and 4 indicating the least. The third carbonyl compound, 2-methylcyclohexanone, is chiral. Starting with either enantiomer of this ketone, write a mechanism to show how this compound racemizes in the presence of aqueous acid . . (c) n ' «r — FLS)T V 2. (20 points) Write the mechanisms of the two reactions below and draw the products. Show + + every step explicitly, including all proton transfers; do not use "+H " and "-H " abbreviations. \o (a ) base-catalyzed hemiacetal hydrolysis O' HO " 10 ( b) base-induced lactone hydrolysis Co T . 3 (15 points) Write a mechanism that accounts for the following transformation. Show each step clearly with curved arrows. Hint: no other product is formed in significant yield. H3 KOtBu O ft!*?* C? . 4 (25 points) As promised, here's a problem from the last HW set. mechanism, showing every step clearly . ^- m Write the complete & ; 3 X rk #fan . 5. (15 points) Write a mechanism to explain the following reaction. (This is one that you haven't seen before; methane is produced as a byproduct.) 6. (25 points) Draw the products of the following reactions, including stereochemistry, where relevant. Label products to indicate stereoisomeric relationships as appropriate. 6 (a ) l . PhjP: 2. nBu-Li 7 (b) )- + ••© CH3CH2-I -78°C + • Li:+ L- dJf J: ! NaBD4 EtOH ( (d) H+ eh - ct {ccJ*C ye* ^ I 7. ( 15 points) How would you convert benzyl bromide to the unsaturated ketone below, using only compounds from the Chemical Store (2nd to last page of this exam)? PhCH2Br & /> *> 1 fry* ) L - .3 C vO vT°i Cf *j rtf (> h O' If ** - o 8. (35 points) Show how you would make the following compounds from malonic ester and any of the other compounds in the Chemical Store . (a ) o OEt T =V

Exam 4 Chem 22 2010

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