1a. In an aldol or Claisen condensation reaction, an enolate ion or ester enolat

Question

1a. In an aldol or Claisen condensation reaction, an enolate ion or ester enolate ion behaves like a _____ and reacts at a _____ .

electrophile

nucleophile

acidic H

alpha carbon

carbonyl carbon

1b. In an aldol condensation, an aldehyde reacts with a base to form an ____ which reacts with an _____ to form a ?-hydroxy aldehyde with undergoes ____ to form a ?,?-unsaturated aldehyde.

enol/enolate/addition

enolate/carbonyl C/substitution

enolate/aldehyde/elimination

1c. In a retro-aldol reaction, a ?-hydroxy aldehyde/ketone reacts with a base. The ____ bond is broken to form ____.

carbonyl carbon/alpha carbon

alpha carbon/beta carbon

carbonyl carbon/beta carbon

2 RCHO/RCOR

acid

ester

1d. In a Claisen condensation, a ____ reacts with a base to form a _____ which reacts with a ester to form a _____.

acid/base/?-keto acid

ester/enol/?,?-unsaturated aldehyde

ester/ester enolate/?-keto ester

1e. In Step 1, Compound A forms a diol and ____. In Step 2, the diol reacts to form ___. In Step 3, ethanol reacts with ___ to form ___.

aldehyde

ketone

alkene

RX

acid

ethyl bromide

ester

Explanation / Answer

1.a. Enolate ion or ester enolate acts as a nucleophile and it reacts with carbonyl carbon, in a condensation reaction.

b. In an aldol condensation, an aldehyde reacts with a base to form an enolate ion which reacts with an aldehyde to form a -hydroxy aldehyde with undergoes elimination to form a ,-unsaturated aldehyde.

c. In a retro-aldol reaction, a -hydroxy aldehyde/ketone reacts with a base. The alpha carbon/beta carbon bond is broken to form 2 RCHO/RCOR.

d.  In a Claisen condensation, an ester reacts with a base to form an ester enolate which reacts with a ester to form a beta-keto ester

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