1. MECHANISM
Structure of Triglycerides:
Triglycerides are esters derived from glycerol and three fatty acids. The general structure of a triglyceride molecule can be represented as:
CH2OCOR1−CHOCOR2−CH2OCOR3
Here, R1, R2, and R3 are long hydrocarbon chains from the fatty acids.
Base-Catalyzed Hydrolysis (Saponification) Mechanism:
Step 1: Nucleophilic Attack by Hydroxide Ion (OH−)
The reaction begins when the hydroxide ion (OH−) attacks the carbonyl carbon of one of the ester linkages in the triglyceride. This nucleophilic attack forms a tetrahedral intermediate:
CH2OCOR1−CHOCOR2−CH2OCOR3 + OH− → CH2OCOR1−CHO(OCOR2)*−CH2OCOR3
The intermediate is denoted by *, indicating the formation of a tetrahedral structure.
Step 2: Collapse of the Tetrahedral Intermediate
The intermediate is unstable and collapses back to a more stable configuration. During this process, the bond between the oxygen atom of the ester and the carbonyl carbon breaks, leading to the formation of an alcohol group and a carboxylate anion:
CHO(OCOR2)* → CH2OH + R2COO−
The R2COO− is the fatty acid anion (soap), and CH2OH is part of the glycerol backbone.
Step 3: Repeat for All Ester Bonds
The above steps are repeated for the other two ester linkages in the triglyceride molecule. Each reaction leads to the formation of one more molecule of fatty acid anion (soap) and the eventual liberation of glycerol:
CH2OCOR1−CHOCOR2−CH2OCOR3 + 3OH− → CH2OH−CHOH−CH2OH + 3RCOO−
Where RCOO− represents the soap molecules formed.
Overall Reaction:
The overall balanced equation for the saponification of a triglyceride with sodium hydroxide is:
CH2OCOR1−CHOCOR2−CH2OCOR3 + 3NaOH → CH2OH−CHOH−CH2OH + 3RCOONa
Here, RCOONa represents the sodium salt of the fatty acids (soap), and CH2OH−CHOH−CH2OH is glycerol.
Structure of Triglycerides:
Triglycerides are esters derived from glycerol and three fatty acids. The general structure of a triglyceride molecule can be represented as:
CH2OCOR1−CHOCOR2−CH2OCOR3
Here, R1, R2, and R3 are long hydrocarbon chains from the fatty acids.
Base-Catalyzed Hydrolysis (Saponification) Mechanism:
Step 1: Nucleophilic Attack by Hydroxide Ion (OH−)
The reaction begins when the hydroxide ion (OH−) attacks the carbonyl carbon of one of the ester linkages in the triglyceride. This nucleophilic attack forms a tetrahedral intermediate:
CH2OCOR1−CHOCOR2−CH2OCOR3 + OH− → CH2OCOR1−CHO(OCOR2)*−CH2OCOR3
The intermediate is denoted by *, indicating the formation of a tetrahedral structure.
Step 2: Collapse of the Tetrahedral Intermediate
The intermediate is unstable and collapses back to a more stable configuration. During this process, the bond between the oxygen atom of the ester and the carbonyl carbon breaks, leading to the formation of an alcohol group and a carboxylate anion:
CHO(OCOR2)* → CH2OH + R2COO−
The R2COO− is the fatty acid anion (soap), and CH2OH is part of the glycerol backbone.
Step 3: Repeat for All Ester Bonds
The above steps are repeated for the other two ester linkages in the triglyceride molecule. Each reaction leads to the formation of one more molecule of fatty acid anion (soap) and the eventual liberation of glycerol:
CH2OCOR1−CHOCOR2−CH2OCOR3 + 3OH− → CH2OH−CHOH−CH2OH + 3RCOO−
Where RCOO− represents the soap molecules formed.
Overall Reaction:
The overall balanced equation for the saponification of a triglyceride with sodium hydroxide is:
CH2OCOR1−CHOCOR2−CH2OCOR3 + 3NaOH → CH2OH−CHOH−CH2OH + 3RCOONa
Here, RCOONa represents the sodium salt of the fatty acids (soap), and CH2OH−CHOH−CH2OH is glycerol.
3.
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