Saponification is a chemical reaction that occurs when a triglyceride (fat or oil) reacts with a strong base such as sodium hydroxide (NaOH), resulting in the formation of glycerol and soap (sodium salts of fatty acids). Here is a step-by-step outline of the reaction mechanism along with structural diagrams:
Step 1: Hydrolysis of Triglyceride
Triglycerides are esters formed from glycerol and three fatty acid chains. In saponification, the triglyceride is hydrolyzed.
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Triglyceride Structure:
- A triglyceride is formed from glycerol and three fatty acids.
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Reaction with Sodium Hydroxide:
- The hydroxide ion (OH⁻) from NaOH attacks the carbonyl carbon of the ester linkage in the triglyceride.
Step 2: Formation of Intermediate
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Tetrahedral Intermediate:
- This attack forms a tetrahedral intermediate where the carbonyl oxygen has a negative charge.
Step 3: Breakage of Ester Bond
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Collapse of Intermediate:
- The intermediate will collapse, breaking the ester bond, resulting in the formation of one molecule of fatty acid (now deprotonated) and 2-monoglyceride.
Step 4: Generate Fatty Acids and Glycerol
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Production of Glycerol and Soap:
- Since there are three fatty acids in a triglyceride, this process occurs three times.
- Each time you will form sodium salts of the fatty acids (the soap) and glycerol.
Step 5: Final Product
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Final Structures:
- The result is glycerol (a triol) and sodium salts of fatty acids (soap).
Overall Reaction
The overall reaction can be summarized as:
\[ \text{Triglyceride} + 3 \text{NaOH} \rightarrow \text{Glycerol} + 3 \text{Fatty Acid Sodium Salts (Soap)} \]
This text representation summarizes the reaction mechanism of saponification. Each step involves specific structural transformations in the reactants to produce glycerol and fatty acid salts (soap).