The reactions of aldehydes and ketones represent the largest and most challenging set of mechanisms you must master for the new MCAT. These mechanisms are more important than any for helping you unravel biochemical reactions. What can seem inscrutably complex in an enzymatic mechanism often can be reduced to a familiar pattern if you have ready access to the concepts governing aldehyde and ketone reactions. Much of the organic that does appear on the new MCAT will be couched to this kind of exercise. The focus of MCAT organic chemistry is seeing whether you can shine the light of organic reaction chemistry onto the biochemical context.
Aldehydes & Ketones Mechanisms
Conceptual Vocabulary Self-Test
Basic Terms Crossword Puzzle
Basic Puzzle Solution
Conceptual Vocabulary for Aldehydes and Ketones
The alpha carbon in an aldehyde or ketone refers to the first carbon after the carbonyl carbon.
In an addition reaction two or more molecules combine to form a larger one.
Enols are alkenes with a hydroxyl group affixed to one of the carbon atoms composing the double bond.
Keto-enol tautomerism refers to a chemical equilibrium between a keto form and an enol.
An aldol adduct is a beta-hydroxy ketone or aldehyde resulting from the addition of a ketone enolate to an aldehyde.
Acetalisation is an organic reaction that involves the formation of an acetal or ketal.
An acetal is a molecule with two single bonded oxygens are attached to the same carbon atom which is also bonded to an alkyl or aryl group and a hydrogen.
A protecting group is introduced into a molecule by chemical modification of a functional group in order to obtain chemoselectivity in a subsequent chemical reaction.
The Grignard reaction is an organometallic chemical reaction involving alkyl- or aryl-magnesium halides with electrophiles.
An enolate anion is the anion of an enol, formed by loss of a proton from the alpha carbon of a carbonyl group.
Nucleophilic conjugate addition occurs by reaction of a nucleophile at the beta position of alpha-beta unsaturated carbonyl compounds.
Tollens' reagent is usually ammoniacal silver nitrate, an oxidizing agent, which is itself reduced to silver metal. It is used as a test for aldehydes.
A ketal is a molecule with two single bonded oxygens attached to the same carbon atom which is also bonded to two alkyl or aryl groups.
A Schiff base is a functional group that contains a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group, but not hydrogen.
An enone is an unsaturated chemical compound or functional group consisting of a conjugated system of an alkene and a ketone.
The cyanohydrin reaction is an organic reaction by an aldehyde or ketone with a cyanide anion or a nitrile to form a cyanohydrin.
The Wolff-Kishner reduction is a chemical reaction that fully reduces an aldehyde or ketone to an alkane.
An enamine is an unsaturated compound derived by the reaction of an aldehyde or ketone with a secondary amine followed by loss of a molecule of water.
The haloform reaction is a chemical reaction where a haloform is produced by the multiple halogenation of a methyl ketone in the presence of a base.
Alkylimino-de-oxo-bisubstitution in organic chemistry is the organic reaction of carbonyl compounds with amines to imines.
The Wittig reaction is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide to give an alkene and triphenylphosphine oxide.
Thioacetals are the sulfur analogue of acetals. They are prepared in a similar way to acetals: by reacting a thiol with an aldehyde.
The iodoform test is a qualitative chemical test for the detection of ketones and aldehydes carrying an alpha methyl group in which the reagents are iodine and sodium hydroxide.
The Clemmensen reduction is a chemical reaction described as a reduction of aldehydes or ketones to alkanes using zinc amalgam and hydrochloric acid.
Reductive amination is a chemical reaction which involves the conversion of a carbonyl group to an amine.
The Michael addition is the nucleophilic addition of an carbanion to an alpha, beta unsaturated carbonyl compound. It is one of tne of the most useful methods for the mild formation of carbon-carbon bonds.
A pinacol coupling reaction is an organic reaction in which a carbon-carbon covalent bond is formed between the carbonyl groups of an aldehyde or a ketone in presence of an electron donor in a free radical process.
The Cannizzaro reaction is a chemical reaction that involves the base-induced disproportionation of an aldehyde lacking a hydrogen atom in the alpha position.
The Corey-Fuchs reaction is a series of chemical reactions designed to transform an aldehyde into an alkyne.
The Johnson-Corey-Chaykovsky reaction is a chemical reaction in which a carbonyl is converted to an epoxide by the action of a sulfonium ylide.
The Willgerodt rearrangement is an organic reaction converting an aryl alkyl ketone to the corresponding amide by reaction with ammonium polysulfide.
The Stork enamine alkylation involves the addition of an enamine to an alpha,beta-unsaturated carbonyl acceptor in a process similar to the Michael reaction. The product is then hydrolyzed by an aqueous acid to produce a 1,5-dicarbonyl compound.
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