More Practice Problems
Give the major organic product(s) for the following reactions. If the reactant splits into 2 pieces,
include both pieces. a)
Answer the following questions about enols and related compounds
a) Circle the major component present in this aqueous equilibrium (standard conditions)
b) For each of the 2 minor components in part A, can we change the physical conditions do make that a major component? If yes, how? If no, why not?
c) Despite your answer to part A, enols are useful intermediates. Briefly explain (1-2 sentences) how that can be?
d) Circle the major component present in this equilibrium (standard conditions)
Answer the following questions about sugars
a) Convert the following artificial sugar, codename Sweetums, into the -pyranose form. A template is provided.
b) Assign the topmost and bottommost chiral centers of the Fischer form of Sweetums as R/S. You won’t get credit for a correct answer unless you show work.
c) Draw the standard Fischer projection forms of the two aldoses that could be reduced to form the following alditol.
Explain (1-2 sentences) why the following experimental observations are not contradictions. Drawings are not required, but may be helpful
a) The Tollens test is an oxidation test for aldehydes. The Tollens reagent (AgNO3) oxidizes aldehydes to carboxylic acids. The first 2 compounds do NOT react with Tollens reagent. And yet the third compound DOES react with Tollens reagent
b) Aminobenzene is an activated aromatic compound towards electrophilic aromatic substitutions. It reacts extremely rapidly with Br2 to brominate at the ortho position. And yet when it reacts with acetyl chloride, the Friedel-Crafts product is not formed.
c) When a sample of pure -D-glucose is mixed with acidic methanol, a mixture of both and methylglucoside are formed.
None of the following reactions will work as proposed to give the indicated product selectively. Briefly explain (1 sentence each) why each reaction won’t work.
Draw curved-arrow mechanisms for the following reactions
c) Choose ONE of the above reactions and explain the driving force for that reaction to work. (1-2 sentences)
We can propose three different mechanisms for the reaction of a phosphate triester with hydroxide: SN2, SN1, and acyl substitution.(R, R’, and R’’ represent substituents)
a) Briefly (1-2 sentences) explain the general logic we would use to distinguish which mechanism is the dominant mechanism. Do NOT provide any specific details.
b) Propose substrate(s) that would allow us to distinguish the mechanisms and explain your logic (words or drawings). It’s fine for you to distinguish all 3 mechanisms with a single substrate, or to use multiple substrates to distinguish the mechanisms in pairs. Hint – you can make R, R’, and R’’ any substituents you want as long as this is still a reaction between a phosphate trimester and an alkoxide.
Propose a synthesis of the following compound. All carbon atoms must come from
1,6-heptdiene and other organic compounds that contain 1 or 2 carbon atoms. You can use other reagents as necessary. You do not have to draw any curved-arrow mechanisms. While you do not have to draw the products of each synthetic step or explain your synthetic logic, you are strongly encouraged to in order to be eligible for more partial credit.
Propose a synthesis of the following compound. All carbon atoms must come from either benzene/bromobenzene/methylbenzene and other organic compounds that contain 1 or 2 carbon atoms. You can use other reagents as necessary. Assume you can distinguish ortho vs para selectivity. You do not have to draw any curved-arrow mechanisms. While you do not have to draw the products of each synthetic step or explain your synthetic logic, you are strongly encouraged to in order to be eligible for more partial credit.
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