The acetoacetic ester synthesis is a carbonyl alkylation reaction. It is used to prepare methyl ketones from primary alkyl halides, lengthening the carbon chain by three atoms. Thus, the product can be visualized as being a "substituted acetone." The reaction consists of three steps: generation of the enolate anion followed by SN2 reaction with a primary alkyl halide, ester hydrolysis under acid conditions, and decarboxylation. Br H₂C H3C 1. NaOEt 2. H₂O* 3. heat H₂C. OEt Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H X CO2 CH3 + EtOH :OH На CH3 CO2 CH3 CH3 CH3

The acetoacetic ester synthesis is a carbonyl alkylation reaction. It is used to prepare methyl ketones from primary alkyl halides, lengthening the carbon chain by three atoms. Thus, the product can be visualized as being a "substituted acetone." The reaction consists of three steps: generation of the enolate anion followed by SN2 reaction with a primary alkyl halide, ester hydrolysis under acid conditions, and decarboxylation. Br H₂C H3C 1. NaOEt 2. H₂O* 3. heat H₂C. OEt Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions H X CO2 CH3 + EtOH :OH На CH3 CO2 CH3 CH3 CH3

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter19: Enolate Anions And Enamines

Section: Chapter Questions

Problem 19.40P: Enamines normally react with methyl iodide to give two products: one arising from alkylation at...

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A problem often encountered in the oxidation of primary alcohols to acids is that esters are sometimes produced as by-products. For example, oxidation of ethanol yields acetic acid and ethyl acetate: Propose a mechanism to account for the formation of ethyl acetate. Take into account the reversible reaction between aldehydes and alcohols:
The acetoacetic ester synthesis is a carbonyl alkylation reaction. It is used to prepare methyl ketones from primary alkyl halides, lengthening the carbon chain by three atoms. Thus, the product can be visualized as being a "substituted acetone." The reaction consists of three steps: generation of the enolate anion followed by SN2 reaction with a primary alkyl halide, ester hydrolysis under acid conditions, and decarboxylation. м Br H3C H3C OEt 1. NaOEt 2. H₂O* 3. heat H₂C. Draw curved arrows to show the movement of electrons in this step of the mechanism. CO₂ EtOH CH3 Arrow-pushing Instructions H3C 1:0: :0: :Br: Br: H₂C CH3 CH3 H3C CH3 7b
CH3 Ph3P-CHCH3 H3C H3C Aldehydes and ketones are converted into alkenes by means of a direct nucleophilic addition called the Wittig reaction. In the reaction, a triphenylphosphorine ylide, also called a phosphorane, adds to an aldehyde/ketone to give a four-membered cyclic intermediate called an oxaphosphetane. The oxaphosphetane is not isolated but instead spontaneously decomposes to release triphenylphosphine oxide and an alkene. Ph3P-CHCH3 H3C The ylide is formed by reaction of triphenylphosphine, a good nucleophile, with a primary alkyl halide in an S 2 reaction, followed by deprotonation of the carbon with a strong base, such as butyllithium. The carbonyl carbon and the carbon originally bonded to the halogen become the two carbons with the double bond in the product alkene :0: CH3 Com The real value of the Wittig reaction lies in its ability to yield an alkene of predictable structure, as the C-C bond is precisely where the C=O bond was in the reactant and no isomers (other than…
Alkynes do not react directly with aqueous acid as do alkenes, but will do so in the presence of mercury(II) sulfate as a Lewis acid catalyst. The reaction occurs with Markovnikov regiochemistry, so the OH group adds to the more highly substituted carbon and the H adds to the less highly substituted carbon. The initial product of the reaction is a vinyl alcohol, also called an enol. The enol immediately rearranges to a more stable ketone via tautomerization. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions -X티 Hö: H-O -CH3 -CH3 H30*
Ph3P-CHCH3 H₂C H3C Aldehydes and ketones are converted into alkenes by means of a direct nucleophilic addition called the Wittig reaction. In the reaction, a triphenylphosphorine ylide, also called a phosphorane, adds to an aldehyde/ketone to give a four-membered cyclic intermediate called an oxaphosphetane. The oxaphosphetane is not isolated but instead spontaneously decomposes to release triphenylphosphine oxide and an alkene. CH3 00 + The ylide is formed by reaction of triphenylphosphine, a good nucleophile, with a primary alkyl halide in an SN2 reaction, followed by deprotonation of the carbon with a strong base, such as butyllithium. The carbonyl carbon and the carbon originally bonded to the halogen become the two carbons with the double bond in the product alkene X m CH3 The real value of the Wittig reaction lies in its ability to yield an alkene of predictable structure, as the C=C bond is precisely where the C=O bond was in the reactant and no isomers (other than E/Z isomers)…
Br Brz CH3 CH3 H3C CH2CI2 H3C Br Electrophilic addition of bromine, Br2; to alkenes yields a 1,2-dibromoalkane. The reaction proceeds through a cyclic intermediate known as a bromonium ion. The reaction occurs in an anhydrous solvent such as CH,Cl). In the second step of the reaction, bromide is the nucleophile and attacks at one of the carbons of the bromonium ion to yield the product. Due to steric clashes, the bromide ion always attacks the carbon from the opposite face of the bromonium ion so that a product with anti stereochemistry is formed. Draw curved arrows to show the movement of electrons in this step of the mechanism. Arrow-pushing Instructions Br: :Br: .CH3 H3C H3C CH3 Br:
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