Question

Two steps in a synthesis of the analgesic ibuprofen include a carbonyl condensation reaction, followed by an alkylation reaction. identify intermediates a and b in the synthesis of ibuprofen.

Answer 1

The intermediate a is $\boxed{{\text{diethyl 2 - }}\left( {{\text{4 - isobutylphenyl}}} \right){\text{malonate}}}$.

The intermediate b is $\boxed{{\text{diethyl 2 - }}\left( {{\text{4 - isobutylphenyl}}} \right){\text{ - 2 - methylmalonate}}}$.

Further explanation:

Carbonyl condensation reaction is the reaction between two carbonyl-containing reactants, one of which must possess an alpha hydrogen atom. The reaction involves the removal of an alpha hydrogen atom by a base. The enolate anion formed from this removal attacks the carbonyl carbon of the second molecule.The result is the formation of a new carbon-carbon bond between the carbonyl carbon atom of one molecule and the alpha-carbon atom of another carbonyl molecule.

Alkylation is defined as the transfer of an alkyl group from one molecule to another. The alkyl group can be transferred in the form of alkyl carbocation, a free radical, a carbanion or a carbene. An alkyl group can be added to benzene molecule by an electrophile aromatic substitution reaction called the Friedel‐Crafts alkylation reaction.

Ibuprofen is the derivative of propionic acid in which one hydrogen atom at position 2 is substituted by a 4-(2-methylpropyl) phenyl group.

Synthesis of ibuprofen form carbonyl condensation and alkylation reaction is as follows:

1. Ibuprofen is synthesized by reacting ethyl 2-(4-isobutylphenyl) acetate with base and diethyl carbonate. In this, the base reacts with the acidic proton to form enolate anion.The enolate anion reacts with diethyl carbonate to generate an intermediate diethyl 2-(4-isobutylphenyl) malonate. This step is the carbonyl condensation reaction.

2. The intermediate 2-(4-isobutylphenyl) malonate reacts with base again and forms enolate. The enolate with treatment with methyl iodide produces an intermediate diethyl 2-(4-isobutylphenyl)-2-methylmalonatediethyl. This step is an alkylation reaction.

3. The second intermediate diethyl 2-(4-isobutylphenyl)-2-methylmalonate on hydrolysis give ibuprofen.

Hence, the intermediate a is diethyl 2-(4-isobutylphenyl) malonate and the intermediate b is diethyl 2-(4-isobutylphenyl)-2-methylmalonate. The synthesis of ibuprofen is shown in the image attached.

Learn more:

1. Calculate number of solutes brainly.com/question/8054051.

2. How many moles of Cl are there in 8 moles of CCl4 brainly.com/question/2094744

Answer details:

Grade: Senior school

Subject: Chemistry

Chapter: Chemical reactions

Keywords: Carbonyl condensation, Alkylation, Friedel‐Crafts alkylation reaction, Ibuprofen, ethyl2-(4-isobutylphenyl) acetate, diethyl 2-(4-isobutylphenyl) malonate and diethyl 2-(4-isobutylphenyl)-2-methylmalonate.

Answer 2

Ibuprofen is synthesized by reacting ethyl 2-(4-isobutylphenyl)acetate with base, the base abstracts the acidic proton and enolate is formed which on reaction with diethyl carbonate generates diethyl 2-(4-isobutylphenyl)malonate (A). diethyl 2-(4-isobutylphenyl)malonate on treatment with Base again looses the acidic proton and forms enolate. The enolate with treatment with Methyl Iodide yields diethyl 2-(4-isobutylphenyl)-2-methylmalonate (B). diethyl 2-(4-isobutylphenyl)-2-methylmalonate on hydrolysis give Ibuprofen.