Question

Write structural formulas to represent the products of the saponification of tripalmitin with \(\mathrm{NaOH}(\mathrm{aq})\).

Short answer

The saponification of tripalmitin with aqueous sodium hydroxide produces glycerol and sodium palmitate (soap). The structural formula for glycerol is \(\mathrm{CHOHCH_{2}OHCH_{2}OH}\). The structural formula for sodium palmitate is \(\mathrm{C_{15}H_{31}COONa}\).

Step-by-step solution

Identify the saponification reaction

Tripalmitin is being reacted with sodium hydroxide (\(\mathrm{NaOH}\)) under aqueous conditions. This is an example of saponification, a type of hydrolysis reaction, which results in the formation of a carboxylic acid (or salt) and an alcohol. In this case, the alcohol is glycerol and the carboxylic acid is palmitic acid, which forms the salt sodium palmitate upon reaction with \(\mathrm{NaOH}\). The overall reaction is: \[ \text{Tripalmitin} + 3\,\mathrm{NaOH} \rightarrow \text{Glycerol} + 3\,\mathrm{Sodium Palmitate} \]

Draw the structural formulas

The structural formula for glycerol is \(\mathrm{CHOHCH_{2}OHCH_{2}OH}\). The structural formula for Sodium Palmitate (soap) is \(\mathrm{C_{15}H_{31}COONa}\). Note: There are three sodium palmitates for each glycerol.

Key concepts

Understanding Tripalmitin

Tripalmitin is a type of triglyceride, which is an ester derived from glycerol and three fatty acid molecules, in this case, palmitic acid. It is a common fat found in many animal and vegetable fats. In the context of saponification, it is crucial as it is the reactant that undergoes hydrolysis with sodium hydroxide (NaOH) to yield glycerol and sodium palmitate, a type of soap. Tripalmitin has a systematic name of glyceryl tripalmitate and can be represented by the formula

• C51H98O6

Understanding the structure and reactivity of tripalmitin is vital in grasping the concept of saponification.

The Role of Sodium Hydroxide

Sodium hydroxide (NaOH), also known as lye, plays a pivotal role in the saponification process. It acts as a strong base that breaks the ester bonds in tripalmitin, liberating the fatty acid chains and glycerol. When used in aqueous solution, NaOH ionizes completely to produce hydroxide ions (OH−). These hydroxide ions are what drive the saponification reaction forward. Because of its strong basic nature, NaOH is highly reactive, and it is essential to handle it with care during the saponification process.

Interpreting Structural Formulas

Structural formulas provide a visual representation of the molecular structure of compounds. They show how atoms are arranged and bonded within a molecule and allow chemists to understand the physical and chemical properties of a substance. In the case of saponification, deciphering the structural formulas of the reactants and products is crucial to understanding the changes that occur during the reaction. These formulas are the blueprints that elucidate the transformation of tripalmitin into glycerol and sodium palmitate through the action of NaOH.

Carboxylic Acid and Saponification

Carboxylic acids are organic acids containing a carboxyl group (C(O)OH). In the saponification of tripalmitin, carboxylic acid groups are part of the ester linkage in the triglyceride molecule. During saponification, these ester linkages are hydrolyzed, resulting in the formation of free carboxylic acids. In aqueous solution with NaOH, the carboxylic acid immediately reacts to form its sodium salt, which in the case of tripalmitin's palmitic acid, becomes sodium palmitate - a core ingredient in soap.

Glycerol's Emergence in Saponification

Glycerol, also known as glycerine, is a simple polyol compound with three hydroxyl (OH) groups. It is a byproduct of saponification when the ester bonds in tripalmitin are hydrolyzed. Glycerol's chemical formula is C3H8O3, and its presence in the reaction signifies the complete hydrolysis of the triglyceride. This substance is not only important for making soap but also has numerous applications in food, pharmaceutical, and cosmetic industries due to its moisturizing properties.

Sodium Palmitate: A Result of Saponification

Sodium palmitate, the sodium salt of palmitic acid, is the surfactant product of the saponification reaction. Structurally, it consists of a long non-polar hydrocarbon chain and a polar carboxylate group (COO− Na+), which gives it amphiphilic properties; meaning it can interact with both water and oils. This dual affinity is what makes sodium palmitate an effective cleansing agent in soaps. Its formation is a key indicator that saponification of tripalmitin is successful, producing substances that are widely used in the soap and detergent industry.