Exam 19: Aldehydes and Ketones: Nucleophilic Addition Reactions

What is the correct structure for 2-hydroxyacetophenone?

Exhibit 19-1 Consider the reaction below to answer the following question(s): -Refer to Exhibit 19-1.The exact position of the equilibrium between ketones/aldehydes and their hydrates depends on the structure of the carbonyl compound.Although the equilibrium favors the carbonyl compound in most cases,cyclopropanone forms a stable hydrate.Explain this phenomenon based on the structures of cyclopropanone and its hydrate.

Of the types of reactions that characterize carbonyl groups,how is the following reaction classified?

Draw: 2,2,2-trichloroethanal (chloral)

Name:

Draw: 2-cyclohexenone

The following substance is heated in the presence of aqueous NaOH.Atoms other than carbon and hydrogen are labeled. The product of the reaction is:

Which of the labeled peaks would allow the distinction of an aldehyde from a ketone based on this spectrum?

Name:

Which of the following functional groups does not contain a carbonyl group?

Exhibit 19-10 Consider the data below to answer the following question(s). C₇H₁₄O IR: 1715 cm−¹ MS: M⁺ at m/z = 114,α-cleavage fragment at m/z = 71, no McLafferty rearrangement fragment ¹H NMR: Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS -Refer to Exhibit 19-10.Propose a structure for this compound.

Exhibit 19-3 Consider the reaction below to answer the following question(s). -Refer to Exhibit 19-3.Write the complete stepwise mechanism for this reaction.Show all electron flow with arrows and show all intermediate structures.

Exhibit 19-2 Consider the data below to answer the following question(s). Cyanohydrins are important intermediates in the synthesis of α-hydroxycarboxylic acids from ketones and aldehydes.The nitrile functional group can be hydrolyzed by aqueous acid to yield a carboxylic acid.Nitriles can also be hydrolyzed to carboxylic acids using aqueous base.Unfortunately,when a cyanohydrin is treated with aqueous base the original carbonyl compound is isolated. -Refer to Exhibit 19-2.Identify the electrophile in the reaction of benzaldehyde with hydrogen cyanide.

Exhibit 19-2 Consider the data below to answer the following question(s). Cyanohydrins are important intermediates in the synthesis of α-hydroxycarboxylic acids from ketones and aldehydes.The nitrile functional group can be hydrolyzed by aqueous acid to yield a carboxylic acid.Nitriles can also be hydrolyzed to carboxylic acids using aqueous base.Unfortunately,when a cyanohydrin is treated with aqueous base the original carbonyl compound is isolated. -Refer to Exhibit 19-2.Formulate a reasonable mechanism for the reaction of the cyanohydrin of benzaldeyhe,shown above,with aqueous NaOH.Show all intermediate structures and all electron flow with arrows.

In the Wittig reaction,a phosphorus ylide adds to a ketone or aldehyde to yield an alkene.Write the complete stepwise mechanism for the Wittig reaction shown below.Show all intermediate structures and all electron flow with arrows.

Exhibit 19-1 Consider the reaction below to answer the following question(s): -Refer to Exhibit 19-1.Many nucleophilic addition reactions of aldehydes and ketones are catalyzed by acid or base.Bases catalyze hydration by:

Exhibit 19-9 Consider the data below to answer the following question(s). C₇H₁₄O IR: 1715 cm−¹ MS: M⁺ at m/z = 114,α-cleavage fragment at m/z = 71, McLafferty rearrangement fragment at m/z = 86. ¹H NMR: 0.92 δ (6H,triplet),1.59 δ (4H,multiplet),2.36 δ (4H,triplet) -Refer to Exhibit 19-9.What functional group is indicated by the IR data?

Draw: 5,5-dimethyl-1,3-cyclohexanedione (dimedone)

Draw: trans-3-isopropylcyclohexanecarbaldehyde

Enamines formed from the cyclic secondary amine pyrrolidine are important intermediates in the synthesis of 1,5-diketones. On the structures provided below,draw arrows showing electron flow for the reaction mechanism for the acetic acid-catalyzed formation of an enamine from cyclohexanone and pyrrolidine.