Dimethylamine (DMA) is a chemical compound with a fishy odor. It is used in various industrial processes, such as producing agricultural chemicals, pharmaceuticals, and surfactants.
| IUPAC name | N-methylmethanamine |
| Molecular formula | C2H7N |
| CAS number | 124-40-3 |
| Synonyms | DMA, N-methylmethanamine, dimethylammonia, methylamine, N-methylmethanamine, N-methylmethanam, N-methylmethanamine hydrochloride |
| InChI | InChI=1S/C2H7N/c1-3-2/h3H,1-2H3 |
Dimethylamine Properties
Dimethylamine Formula
Dimethylamine is an organic compound with the chemical formula C2H7N. It is a derivative of ammonia, where two of the three hydrogen atoms have been replaced by methyl groups. Its formula represents the composition of one molecule of dimethylamine, which contains two carbon atoms, seven hydrogen atoms, and one nitrogen atom.
Dimethylamine Molar Mass
The molar mass of DMA is 45.09 g/mol. It is a relatively small molecule, which contributes to its low boiling point and high vapor pressure. The molar mass is the mass of one mole of DMA and is calculated by adding up the atomic masses of all the atoms in the molecule.
Dimethylamine Boiling Point
The boiling point of DMA is -6.3°C. This low boiling point makes DMA a volatile and flammable liquid. It boils at a lower temperature than water, which means it can easily evaporate when exposed to air. The boiling point of a substance is the temperature at which it changes from a liquid to a gas.
Dimethylamine Melting Point
The melting point of DMA is -92°C. It is a colorless liquid at room temperature but can freeze to form a white crystalline solid below its melting point. The melting point of a substance is the temperature at which it changes from a solid to a liquid.
Dimethylamine Density g/mL
The density of DMA is 0.67 g/mL. It is less dense than water, which has a density of 1 g/mL. This means that DMA will float on water. The density of a substance is the mass per unit volume of the substance.
Dimethylamine Molecular Weight
The molecular weight of DMA is 45.09 g/mol. It is the sum of the atomic weights of all the atoms in a molecule of DMA. The molecular weight is useful in determining the amount of a substance needed to make a certain volume or concentration of a solution.
Dimethylamine Structure
The structure of DMA consists of a nitrogen atom bonded to two methyl groups and one hydrogen atom. It is a simple primary amine with a pyramidal shape. The nitrogen atom has a lone pair of electrons, which makes DMA a weak base.
Dimethylamine Solubility
DMA is soluble in water, ethanol, and diethyl ether. It forms hydrogen bonds with water molecules, which allows it to dissolve readily in water. Its solubility in organic solvents such as ethanol and diethyl ether is due to its ability to form intermolecular hydrogen bonds with the solvent molecules.
| Appearance | Colorless liquid |
| Specific Gravity | 0.666 g/mL at 25°C |
| Color | Colorless |
| Odor | Fishy, ammoniacal |
| Molar Mass | 45.09 g/mol |
| Density | 0.666 g/mL at 25°C |
| Melting Point | -92°C |
| Boiling Point | -6.3°C |
| Flash Point | -32°C |
| Water Solubility | Soluble in water |
| Solubility | Soluble in ethanol and diethyl ether |
| Vapor Pressure | 522 mmHg at 20°C |
| Vapor Density | 1.53 (air = 1) |
| pKa | 10.73 |
| pH | 11.1 |
Dimethylamine Safety and Hazards
DMA can be hazardous if not handled properly. It is highly flammable and can ignite easily in the presence of heat, sparks, or flames. It is also toxic and can cause irritation to the eyes, skin, and respiratory system. Direct exposure to DMA can lead to headaches, dizziness, and nausea. It is important to use protective gear such as gloves, goggles, and respirators when handling DMA. It should be stored in a cool, dry place away from heat and sources of ignition. In case of spillage or exposure, it should be handled according to appropriate safety protocols.
| Hazard Symbols | F, T |
| Safety Description | Highly flammable, toxic, corrosive |
| UN IDs | UN 1032 |
| HS Code | 2921.19.00 |
| Hazard Class | 2.1 (Flammable gas) |
| Packing Group | II |
| Toxicity | LD50 (oral, rat) 230 mg/kg; LC50 (inhalation, rat) 1660 ppm/4h |
Dimethylamine Synthesis Methods
Several methods exist to synthesize DMA.
One common method is through the reaction of methanol and ammonia in the presence of a catalyst. Chemists can distill and purify the resulting product to obtain pure DMA.
Another method involves the reaction of formaldehyde and ammonium chloride in the presence of a base, such as sodium hydroxide. The reaction produces methylamine, and one can then react with formaldehyde to yield DMA.
To synthesize DMA, one can react with dimethyl sulfate and ammonia. This reaction is exothermic and produces DMA and ammonium sulfate as byproducts. However, chemists do not commonly use this method due to the hazardous nature of dimethyl sulfate.
To obtain DMA, one can react methyl chloride with ammonia. This reaction also produces ammonium chloride as a byproduct.
Overall, the synthesis of DMA requires careful handling and the use of appropriate equipment and protective gear due to the hazardous nature of the starting materials and reaction conditions.
Dimethylamine Uses
DMA has a wide range of applications in various industries due to its unique chemical properties. Here are some of the common uses of DMA:
- Agricultural Industry: Various herbicides, insecticides, and fungicides use DEA as an intermediate in their production.
- Pharmaceuticals: Used as a starting material for the synthesis of various pharmaceuticals, including local anesthetics, antibiotics, and antihistamines.
- Rubber Industry: Used as a vulcanization accelerator in the rubber industry, which improves the physical properties of rubber products.
- Petroleum Industry: Used as a corrosion inhibitor and neutralizing agent in the refining of petroleum.
- Water Treatment: Used as a flocculant in water treatment to remove suspended solids and other impurities.
- Solvent: Used as a solvent in the production of various chemicals, including resins, dyes, and plastics.
- Textile Industry: Used as a dye intermediate and as a finishing agent in the textile industry.
- Personal Care: Also used as an ingredient in various personal care products, including shampoos and conditioners, as it acts as a pH adjuster.
Questions:
Q: Which of the following represents the complete neutralization of dimethylamine?
A: The complete neutralization of DMA occurs when it reacts with hydrochloric acid to form dimethylammonium chloride and water.
Q: What type of product results when 3-pentanone reacts with dimethylamine?
A: When 3-pentanone reacts with DMA, the resulting product is an imine.
Q: Is dimethylamine safe for hair?
A: DMA is commonly used in hair care products as a pH adjuster and is considered safe for use at low concentrations.
Q: Is dimethylamine good for hair?
A: DMA can be beneficial for hair when used in hair care products at appropriate concentrations as it can help to improve the efficacy of other ingredients.
Q: What is dimethylamine?
A: DMA is an organic compound with the chemical formula (CH3)2NH. It is a colorless gas with a strong odor and is commonly used in various industrial processes.
Q: Is dimethylamine a base?
A: DMA is a weak base, as it can accept a proton from a water molecule to form a hydroxide ion and a methylammonium ion.
Q: Is cetearyl dimethylamine curly girl?
A: Cetearyl DMA is not considered curly girl approved, as it is a synthetic ingredient commonly used in hair care products and may not be suitable for those following the curly girl method.
Q: How to find pka of dimethylamine?
A: The pKa of DMA can be found experimentally by measuring the pH of a solution of known concentration of DMA and its conjugate acid, and using the Henderson-Hasselbalch equation to calculate the pKa value.
Q: How would you prepare 100 mL of a buffer with pH 11.0 from dimethylamine?
A: To prepare a buffer with pH 11.0 from DMA, one would need to mix a certain amount of DMA with its conjugate acid, dimethylammonium chloride, in a specific ratio to achieve the desired pH. The exact amounts would depend on the desired buffer capacity and the pKa of the conjugate acid.