Question

Trimyristin is a white crystalline fat, m.p. \(54-55^{\circ}\), obtainable from nutmeg, and is the principal constituent of nutmeg butter. Hydrolysis of trimyristin with hot aqueous sodium hydroxide gives an excellent yield of myristic acid, m.p. \(52-53^{\circ}\), as the only fatty acid. What is the structure of trimyristin?

Short answer

The structure of trimyristin can be determined by analyzing the hydrolysis reaction with hot aqueous sodium hydroxide, which produces myristic acid as the only fatty acid. The structure of trimyristin consists of three myristic acid molecules and a glycerol molecule, connected through ester linkages. The resulting structure can be written as: \(\mathrm{CH_3(CH_2)_{12}COOCH_2CH\left(OOC(CH_2)_{12}CH_3\right)CH_2OOC(CH_2)_{12}CH_3}\).

Step-by-step solution

Understanding Hydrolysis

Hydrolysis is a chemical reaction wherein a molecule gets split due to the reaction with water. In this exercise, hydrolysis of trimyristin results in the formation of myristic acid and another product. The hydrolysis of esters, for instance, occurs when a molecule reacts with water, causing the ester to break apart into its constituent parts.

Identifying the Ester Functional Group

Given that the only fatty acid produced during this reaction is myristic acid, we can presume that trimyristin contains three myristic acid molecules as these are what remain after the hydrolysis process. Myristic acid has the structural formula: \(\mathrm{CH_3(CH_2)_{12}COOH}\) Since trimyristin is the ester of three myristic acid molecules, we need to determine what the other part of the molecule is. Esters are formed through the reaction between a carboxylic acid and an alcohol, producing the ester and water. Given that there are three myristic acid molecules, we can assume that the alcohol used has three hydroxy groups (\(\mathrm{-OH}\)).

Identifying the Alcohol

The most common alcohol with three hydroxy groups is glycerol, which has the structural formula: \(\mathrm{HOCH_2CH(OH)CH_2OH}\) This would make the hydrolysis reaction as follows: Trimyristin + 3H₂O -> 3Myristic Acid + Glycerol

Deriving the Structure of Trimyristin

Now that we have identified the ester functional group and have determined that glycerol is the other part of the molecule, we can draw the structure of trimyristin. The ester functional group is formed by combining the carboxylic acid group of the myristic acid and the hydroxy group of glycerol, resulting in the following ester linkage: \(\mathrm{CH_3(CH_2)_{12}COO-CH_2}\) There will be three of these ester linkages to account for the fact that there are three myristic acid molecules. The structure for trimyristin would therefore be: \(\mathrm{CH_3(CH_2)_{12}COOCH_2CH\left(OOC(CH_2)_{12}CH_3\right)CH_2OOC(CH_2)_{12}CH_3}\)

Key concepts

Trimyristin

Trimyristin is a fascinating compound that you encounter in your chemistry studies. It's a type of triglyceride, which means it is a glycerol molecule bonded to three fatty acid chains. In the case of trimyristin, all three fatty acid chains are composed of myristic acid. You can find this compound naturally occurring as the main ingredient in nutmeg butter, where it presents as a white crystalline fat with a melting point of around 54-55°C. This makes it quite stable and gives it a solid form at room temperature.

In industrial and laboratory settings, trimyristin is often subjected to various reactions to create other useful compounds. One of its important reactions is hydrolysis, where it is broken down into its constituent molecules. Researchers and chemists who hydrolyze trimyristin can obtain pure myristic acid and glycerol, its two component molecules. Understanding trimyristin gives insight into the chemistry of triglycerides and their role in both food and chemical industries.

Myristic Acid

Myristic acid is a saturated fatty acid, identifiable by its molecular formula: \(\mathrm{CH_3(CH_2)_{12}COOH}\). This fatty acid consists of a 14-carbon chain terminating in a carboxyl group, and is known for its ability to act as a building block in various chemical reactions. When you consider hydrolyzing trimyristin, myristic acid is the primary fatty acid product of this process.

With a melting point of 52-53°C, myristic acid is solid at room temperature and is often used in the production of soaps, cosmetics, and as a flavor ingredient. Its saturated nature means it does not contain any double bonds, contributing to its stability and suitability for these applications. Chemically, it plays an important role not only in product manufacturing but also as an essential component in living organisms, often forming part of membrane lipids.

Glycerol

Glycerol, also known as glycerin, is a simple polyol compound that serves as the backbone for triglycerides like trimyristin. Its structure can be illustrated by the formula: \(\mathrm{HOCH_2CH(OH)CH_2OH}\). Featuring three hydroxy groups, glycerol is a sweet-tasting, non-toxic substance that is used widely in pharmaceuticals, cosmetics, and food industries.

During the hydrolysis of trimyristin, glycerol is released alongside myristic acid. This property makes glycerol a versatile molecule in many chemical reactions, offering a benign solvent and moisturizing agent. Its ability to bond with fatty acids to form esters is instrumental in the creation and breakdown of triglycerides, underscoring its significant role in both biochemical processes and commercial formulations.

Fatty Acids

Fatty acids are long-chain hydrocarbons that contain a carboxylate group at one end. They are vital components of lipids in the dietary sense and can be either saturated (no double bonds) or unsaturated (one or more double bonds). In trimyristin, the fatty acid chains attached to glycerol are myristic acid, which is a saturated fatty acid.

Saturated fatty acids like myristic acid are essential for the structural integrity of various biological membranes and can be highly beneficial or essential as part of a balanced diet. Understanding their role helps in both nutritional science and biochemistry. The length and saturation of the fatty acid chains significantly impact the physical properties and health implications of these acids.

Chemical Reaction

Chemical reactions are processes where substances transform into new compounds, and in organic chemistry, these involve changes at the molecular level. Hydrolysis is a specific type of chemical reaction where molecules are split into smaller units by the addition of water. It's crucial in the context of breaking down esters such as trimyristin into myristic acid and glycerol.

In hydrolysis, water molecules provide protons and hydroxide ions that disrupt ester bonds, freeing the fatty acid chains from the glycerol backbone. This reaction is not only central to laboratory settings but also to biological processes where fats and oils are metabolized. Familiarizing yourself with hydrolysis broadens your understanding of both industrial applications and life-sustaining processes in living organisms.