Aldehydes Ketones And Carboxylic Acids

The correct option is(D): by increasing pressure and decreasing temperature,

Any change in the concentration, pressure and temperature of the reaction results in change in the direction of equilibrium. This change in the direction of equilibrium is governed by
Le-Chatelier's principle. According to
Le-Chatelier's principle, equilibrium shifts in die opposite direction to undo the change.

(a) Increasing the concentration of
On increasing the concentration of . the equilibrium shifts in the backward direction where concentration of decreases
(b) Decreasing the pressure: Since, (number of moles), therefore, equilibrium shifts in the backward direction where number of moles are increasing.
(c) Decreasing the concentration of and .
Equilibrium shifts in the backward direction when concentration of and decreases.
(d) Increasing pressure and decreasing temperature: On increasing pressure, equilibrium shifts in the forward direction where number of moles decreases. It is an example of exothermic reaction therefore decreasing temperature favours the forward direction

When carboxylic acids react with PCl₅, they form acid chlorides. These acid chlorides, when reacted with benzene or its derivatives, result in the formation of ketones. This chemical transformation is commonly referred to as Friedel-Crafts acylation, and it is typically carried out in the presence of anhydrous AlCl₃. Subsequently, ketones, when subjected to reactions with Grignard reagents, lead to the synthesis of tertiary alcohols.

To solve this problem, we need to consider the reaction mechanism between acetone and 2-pentanone in the presence of dilute NaOH followed by heating. This is an example of an aldol condensation, which involves the following steps:

1. Deprotonation: Under basic conditions, acetone, being an alpha-beta unsaturated ketone, undergoes deprotonation at the alpha carbon, forming an enolate ion.
2. Nucleophilic Attack: The enolate ion acts as a nucleophile and attacks the carbonyl carbon of 2-pentanone, leading to the formation of a β-hydroxy ketone (aldol addition product).
3. Dehydration: Upon heating, the β-hydroxy ketone undergoes dehydration (loss of water) to form an α,β-unsaturated ketone through the elimination of the hydroxyl group and adjacent hydrogen.

The structures of the possible products are analyzed to determine which cannot be formed from this reaction.

Explanation: The product cannot be formed because it is not an α,β-unsaturated ketone but instead resembles an isomeric structure that would require a different reaction mechanism, likely involving structural rearrangement that is not accounted for by a simple aldol condensation.

The reaction involves the Grignard reagent ( ) reacting with dry in the presence of ether to form a product denoted as . This intermediate product is then treated with water and acid ( ) to eventually yield a carboxylic acid ( ).

The key reactions occur as follows:

• The Grignard reagent reacts with carbon dioxide to form a carboxylate intermediate:
  
• The carboxylate intermediate is in the given reaction sequence.
• Upon hydrolysis with , the carboxylate is converted to the corresponding carboxylic acid:
  

Thus, the correct identity for is the carboxylate salt, which matches the option: .