Chemistry Chapter 19 Test Questions Essay

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?-Dicarbonyl
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Compounds that have two carbonyl groups, >C=O, that are separated by one carbon atom, with the general formula, RCOCH2COR
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Decarboxylation of ?-keto acids
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A reaction whereby a ?-keto carboxylic acid, or a ?-dicarboxylic acid, loses a carboxyl group as carbon dioxide, CO2
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Claisen condensation
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Base-catalyzed condensation of an ester containing two ?-hydrogens with a molecule of the same ester to produce a ?-keto ester; the overall reaction involves loss of an ?-hydrogen from one ester and loss of an ethoxide ion from the other ester. Also called acetoacetic ester condensation
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Dieckmann condensation
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An intramolecular Claisen condensation that forms a five- or six- membered ring, which is a base-catalyzed cyclization of a dicarboxylic acid ester to produce a cyclic ?-ketoester. Also called Dieckmann reaction or Dieckmann cyclization
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Crossed Claisen condensation
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Claisen condensation between an ester with no ?-hydrogens, and a different ester with two ?-hydrogens.
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Acetoacetic ester synthesis
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Base-catalyzed alkylation or arylation of the enolate of a ?-ketoester to produce a monoalkyl or dialkyl acetoacetic ester; subsequent hydrolysis of the ester and decarboxylation produces a monosubstituted or disubstituted acetone (methyl ketone).

Base-catalyzed alkylation or arylation of the enolate of a ?-ketoester to produce a monoalkyl or dialkyl acetoacetic ester; subsequent hydrolysis of the ester and decarboxylation produces a monosubstituted or disubstituted acetone (methyl ketone)

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Synthetic equivalent
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A reagent whose structure, when incorporated into a product, appears to have originated from one type of precursor, when as a reactant it actually had a different origin. For example, the ethyl acetoacetate enolate ion serves as the synthetic equivalent of the acetone enolate ion, and the diethyl malonate enolate ion serves as the synthetic equivalent of the ethyl acetate enolate ion
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Malonic ester synthesis
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Synthesis based on the strongly activated methylene group of malonic esters, which easily deprotonate in base to form a resonance-stabilized anion that can be alkylated or acylated to produce a monoalkyl or dialkyl malonic ester; subsequent hydrolysis of the ester and decarboxylation produces a monosubstituted or disubstituted acetic acid
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Active hydrogen compound
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A compound that has two electron-withdrawing groups attached to the same methylene carbon atom, Z-CH2-Z’, which makes the methylene hydrogen atoms acidic, with a pKa between 3 and 13. Also called active methylene compound.
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Direct alkylation of esters
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An alkylation reaction involving the conversion of an ester into its enolate with LDA (lithium diisopropylamide), followed by an SN2 reaction with a primary alkyl halide
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1,3-Dithiane derivative
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A class of six-membered ring thioacetals produced by the reaction of an aldehyde with 1,3-propanedithiol; the hydrogen atom on the carbon between the sulfur atoms is acidic with a pKa of 32; it can be deprotonated into a carbanion by reaction with an alkyl lithium compound
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Umpolung
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A reversal of polarity of a carbonyl carbon atom in the alkylation of 1,3-dithianes
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Knoevenagel condensation
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Condensation of an aldehyde or ketone with an active hydrogen compound, which is catalyzed by a weak base, such as an amine
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Michael addition
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Base-promoted conjugate addition (1,4-addition) of a resonance stabilized carbanion nucleophile, such as a deprotonated active hydrogen compound (Michael donor), to an electrophilic conjugated double bond, such as an ?,?-unsaturated carbonyl compound (Michael acceptor). Also called Michael reaction or Michael condensation
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Mannich reaction
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The reaction of the enol form of a carbonyl compound with the imine derived from formaldehyde and a primary or secondary amine to produce a ?-aminoalkyl carbonyl compound (Mannich base).
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Enamine
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A vinyl amine, usually generated by the acid-catalyzed reaction of a secondary amine with an aldehyde or ketone, which has the general formula: R2C=C(NR2)R
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Stork enamine reaction
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Synthesis of an ?-alkyl or ?-acyl carbonyl compound from the reaction of an enamine with an alkyl or acyl halide

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