The key difference between dimethylamine and trimethylamine is that dimethylamine contains a central nitrogen atom attached with two methyl groups to the same nitrogen atom, whereas trimethylamine contains three methyl groups attached to the same nitrogen atom.
Dimethylamine and trimethylamine are two important amine compounds that are useful in many different industrial and laboratory applications.
CONTENTS
1. Overview and Key Difference
2. What is Dimethylamine
3. What is Trimethylamine
4. Dimethylamine vs Trimethylamine Group in Tabular Form
5. Summary – Dimethylamine vs Trimethylamine
What is Dimethylamine?
Dimethylamine is an organic compound having the chemical formula (CH3)2NH. This compound has two methyl groups attached to the amine group. Therefore, the nitrogen atom in the amine group has only one hydrogen atom attached to it other than the methyl groups. Dimethylamine occurs as a colourless gas and has a fishy odour. Moreover, its molar mass is 45.08 g/mol. We categorize it as a secondary amine because of the two methyl groups.
This compound occurs naturally in many plants and animals. We can also produce this compound via the reaction between methanol and ammonia in the presence of a catalyst, high temperature, and pressure conditions.
Figure 1: The Chemical Structure of Dimethylamine
The density of dimethylamine is 649.6 kg/m3. The melting point of this compound is -93 degrees Celsius, whereas the boiling point can range from 7-9 degrees Celsius. It has poor solubility in water. It can react with acids to form salts, including dimethylamine hydrochloride (which is an odorless white solid having a melting point of 171.5 degrees Celsius). We can also produce dimethylamine from the catalytic reaction of methanol and ammonia at elevated temperatures and high pressure.
What is Trimethylamine?
Trimethylamine is an organic compound having the chemical formula N(CH3)3. This compound can be found as a colorless, hygroscopic, and flammable tertiary amine that occurs as a gas at room temperature, but it is typically sold in the market as a 40% solution in water. It is a nitrogenous base that can be readily protonated to get the trimethylammonium cation.
Figure 02: The Chemical Structure of Trimethylamine
The trimethylamine molecule can be identified as a good nucleophile. Therefore, it is widely used in many industrial applications. It is also useful in the synthesis of choline, tetramethylammonium hydroxide, plant growth regulators or herbicides, strongly basic anion exchange resins, etc. When it is in a high concentration, it has an ammonia-like odor, and at lower concentrations, it has a fishy odor. At higher concentrations, it can cause necrosis of mucous membranes on contact.
The molar mass of this compound is 59.112 g/mol. The density of this compound is 670 kg/m3. The melting point of this compound is -117.20 degrees Celsius, while the boiling point is 3-7 degrees Celsius. It is miscible with water, and the vapor pressure is 188.7 kPa at 20 degrees Celsius.
When considering the preparation of trimethylamine, it can be prepared by the reaction of ammonia and methanol with the use of a catalyst. This reaction also co-produces other methylamines, such as dimethylamine and methylamine.
What is the Difference Between Dimethylamine and Trimethylamine?
Dimethylamine and trimethylamine are important amine compounds. The key difference between dimethylamine and trimethylamine is that dimethylamine contains a central nitrogen atom attached with two methyl groups to the same nitrogen atom, whereas trimethylamine contains three methyl groups attached to the same nitrogen atom.
How to Distinguish Dimethylamine and Trimethylamine?
When these two compounds are mixed with Hinsberg’s reagent separately, dimethylamine can produce N,N-dimethyl benzene, which is insoluble in aqueous KOH solution because it has two methyl groups attached to the nitrogen atom, whereas trimethylamine does not react with this reagent because it has three methyl groups attached to the same nitrogen atom.
The below infographic presents the differences between dimethylamine and triethylamine in tabular form for side-by-side comparison.
Summary – Dimethylamine vs Trimethylamine
The key difference between dimethylamine and trimethylamine is that dimethylamine contains a central nitrogen atom attached with two methyl groups to the same nitrogen atom whereas trimethylamine contains three methyl groups attached to the same nitrogen atom.
Reference:
1. “Trimethylamine.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine.
Image Courtesy:
1. “Dimethylamine-2D-skeletal” (Public Domain) via Commons Wikimedia
2. “Trimethylamine” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia