**Basic Difference between Aldol Condensation and Claisen Condensation Reaction**

Aldol condensation and Claisen condensation are two important organic reactions that involve the formation of new carbon-carbon bonds. Both reactions are examples of condensation reactions, where two molecules combine to form a larger molecule with the elimination of a small molecule such as water. However, there are some key differences between these two reactions.

**1. Reactants:**
- Aldol condensation involves the reaction between an aldehyde or ketone with an enolate ion or another aldehyde/ketone.
- Claisen condensation, on the other hand, involves the reaction between two ester molecules or an ester molecule with a ketone.

**2. Mechanism:**
- In aldol condensation, the reaction proceeds through the formation of an enolate ion by deprotonation of the α-carbon of the carbonyl compound. The nucleophilic enolate attacks the carbonyl carbon of another aldehyde or ketone, leading to the formation of a β-hydroxy carbonyl compound (aldol product).
- In Claisen condensation, the reaction proceeds through the formation of an alkoxide ion by deprotonation of the α-carbon of the ester. The alkoxide ion then attacks the carbonyl carbon of another ester or a ketone, resulting in the formation of a β-keto ester or a β-diketone.

**3. Nature of the Products:**
- Aldol condensation typically results in the formation of an aldol product, which is a β-hydroxy carbonyl compound. This product can exist in two forms: the aldehyde form and the enol form.
- Claisen condensation generally leads to the formation of a β-keto ester or a β-diketone. These products also have keto-enol tautomeric forms.

**4. Reaction Conditions:**
- Aldol condensation reactions are usually carried out in basic conditions to facilitate the formation of the enolate ion, which is the nucleophile.
- Claisen condensation reactions are typically performed in the presence of a strong base, such as sodium ethoxide or sodium hydroxide, to generate the alkoxide ion, which serves as the nucleophile.

**5. Stereochemistry:**
- In aldol condensation, if the reacting carbonyl compound is asymmetric, the products may show stereoisomerism.
- In Claisen condensation, stereoisomerism is not observed as the reaction occurs between identical or similar molecules.

In summary, while both aldol condensation and Claisen condensation reactions involve the formation of new carbon-carbon bonds through the elimination of a small molecule, they differ in terms of reactants, mechanism, nature of products, reaction conditions, and stereochemistry. Understanding these differences is important in organic synthesis and the design of specific reactions for the synthesis of desired compounds.

Aldehyde/ketones having alpha hydrogen in presence of dilute base give aldol condensation reaction.Whereas ESTER having alpha hydrogen in presence of dilute base undergoes claisen condensation reaction.