Aldehydes and Ketone: Nucleophilic Addition Reactions

Flashcards covering the nomenclature, preparation, reactions (nucleophilic addition), and spectroscopy of aldehydes and ketones based on Chapter 19 materials.

Aldehydes

Chemical compounds characterized by the formula $RCHO$ and the presence of a carbonyl functional group ($C=O$).

Ketones

Chemical compounds characterized by the formula $R_2CO$ and the presence of a carbonyl functional group ($C=O$).

Dess-Martin periodinane (DMP)

A reagent used in dichloromethane solvent for the oxidation of primary alcohols to aldehydes and secondary alcohols to ketones.

Diisobutylaluminum hydride

A reagent used for the partial reduction of an ester to yield an aldehyde.

Nucleophilic addition reaction

A reaction where a nucleophile ($Nu^-$) adds to the carbonyl carbon at an angle of approximately $75^\text{o}$ to the plane of the $sp^2$ orbitals, producing a tetrahedral alkoxide ion intermediate.

Cyanohydrins

The products of the nucleophilic reaction between aldehydes (or unhindered ketones) and $HCN$, characterized by a nitrile group and a hydroxyl group on the same carbon.

Imine

A compound with the general structure $R_2C=NR$, formed by the reaction of an aldehyde or ketone with a primary amine ($RNH_2$).

Enamine

A compound with the general structure $R_2N-CR=CR_2$, formed by the reaction of an aldehyde or ketone with a secondary amine ($R_2NH$).

Wolff–Kishner Reaction

A reaction where an aldehyde or ketone is treated with hydrazine ($H_2NNH_2$) and $KOH$ to convert the carbonyl group into an alkane.

Acetal

A compound with the general structure $R_2C(OR')_2$ produced by the reversible acid-catalyzed reaction of an aldehyde or ketone with $2$ equivalents of an alcohol.

Hemiacetal

A hydroxy ether tetrahedral intermediate formed by the nucleophilic addition of one equivalent of alcohol to a carbonyl group.

Cannizzaro reaction

The nucleophilic addition of $OH^-$ to an aldehyde to give a tetrahedral intermediate that expels a hydride ion, resulting in the simultaneous oxidation of one aldehyde molecule and reduction of another.

Conjugate addition

Also called $1,4$-addition, it is the addition of a nucleophile to the $C=C$ double bond of an $\text{α,β}$-unsaturated aldehyde or ketone.

$\text{α,β}$-Unsaturated aldehyde or ketone

A compound containing a double bond conjugated with a carbonyl group, where the oxygen atom withdraws electrons to make the $\text{β}$ carbon electrophilic.

Wittig Reaction

The addition of phosphorus ylides to aldehydes and ketones to yield alkenes.

McLafferty rearrangement

A mass spectrometry fragmentation pathway occurring in aliphatic aldehydes and ketones that possess hydrogens on their gamma ($\text{γ}$) carbon atoms.

$\text{α}$-Cleavage

A mass spectrometry fragmentation involving the cleavage of the bond between the carbonyl group and the $\text{α}$ carbon, yielding a neutral radical and an oxygen-containing cation.