Textbook: Loudon 5th Ed. (2009)

Chapter 19: The Chemistry of Aldehydes and Ketones. Carbonyl-Addition Reactions

Practice Problems (No matching mendel sets were found.)

Individual Problems

Problem # 669
 

In your own words, what is the major difference in the addition of a Grignard reagent to an oxidation state III carbonyl (ester/acid chloride) versus an oxidation state II carbonyl? (aldehyde/ketone)

Problem # 712

Show what combination of amine and carbonyl would result in each imine or enamine.

Problem # 668

Show how each alcohol can be prepared from a combination of a carbonyl and a Grignard reagent.

Problem # 671

You may have noticed that the "solvent of choice" for many organometallic compounds such as Grignard reagents is ether (short for diethyl ether).

Why is it that for Grignard reactions this solvent is used over ethyl acetate, or protic solvents such as ethanol?

Problem # 705

Carbonyls are in equilibrium with their hydrate forms. This equilibrium happens in both acid and base.

Let's go through this equilibrium under basic conditions. Draw a mechanism using curved arrows for each reaction below.

Remember that under basic conditions, most species are either neutral or negatively charged, and rarely positively charged. So your structures will contain either ROH or RO-, but not ROH2+.

 

a) Carbonyl to Hydrate

Notice that no oxygen is ever positive during these basic mechanisms (always negative or neutral).

b) Hydrate to Carbonyl

Problem # 706

Carbonyls are in equilibrium with their hydrate forms. This equilibrium happens in both acid and base.

Let's go through this equilibrium under acidic conditions. Draw a mechanism using curved arrows for each reaction below.

Remember that under acidic conditions, most species are either neutral or positively charged, and rarely negatively charged. So your structures will contain either ROH or ROH2+, but not RO-.

 

a) Carbonyl to Hydrate (acidic)

b) Hydrate to Carbonyl (acidic)

Problem # 710
 

Rank the carbonyls A-D below in order of decreasing electrophilicity (reactivity with nucleophiles).

(1 = Most reactive).  Explain your reasoning.

Problem # 714

Complete each synthesis below. All carbon sources must come from alkenes.

Each synthesis will involve protecting groups.

Problem # 715

α-D-glucose is shown below.

a) Is α-D-glucose an acetal, hemiacetal, ketal, or hemiketal?

b) Draw the carbonyl form of α-D-glucose.

Problem # 674
 

Show a mechanism for the reduction of butyrolactone using LiAlH4.

Problem # 670
 

Draw out the mechanism for the addition of excess phenyl Grignard to the carbonyl compound below.

Problem # 707

The overall mechanism for imine formation is shown below. (This isn't a real mechanism, just an outline)

 

Use curved arrows to draw the full mechanism for imine formation under acidic conditions. (I've added outlines of the intermediate structures for you to use as a guide). This mechanism is similar to that in problem 706 (carbonyl hydrate equilibria).

Problem # 711

Show two ways of preparing the alkene below via the Wittig reaction starting from triphenyl phosphine (PPh3).

Is one route better than the other? Why?

Problem # 713

When a carbonyl is treated with semicarbazide under acidic conditions an "imine" is produced called a semicarbazone.

Which of the two products below is the correct structure for a semicarbazone? Explain.

Problem # 672

Compound A has molecular formula C6H12O and shows a sharp peak at 1,710 cm-1 in its IR spectrum.

Treatment with 1 equivalent of phenyl Grignard yields compound B, which has formula C12H18O and whose IR shows a broad peak at 3,350 cm-1.

Compound B's 1H NMR spectrum is shown below. Determine the structures of compounds A and B.