CH3NH2 [Chemical Structure, Lewis Structure, Acid or Base]

CH3NH2 is not a commonly known chemical, but it is used in a variety of important chemical products. What is CH3NH2?

CH3NH2 is methylamine, an organic compound, specifically a colorless gas and a derivative of ammonia. It is similar to ammonia when it comes to chemical structure. The difference is that it has a methyl group instead of a hydrogen atom. Also, CH3NH2 is the simplest major amine with a molecular weight of 31.057 g/mol. 

Manufacturers sell methylamine as anhydrous gas in pressurized appropriate containers. You can also obtain it dissolved in water, ethanol, methanol, or tetrahydrofuran. Chemists use methylamine as a building block to synthesize various commercial compounds in the market.

Moreover, methylamine is a Bronsted base. Meaning it accepts a proton during an acid-base reaction. Under normal conditions, CH3NH2 has a strong fishy odor and is a colorless gas or liquid.

Read on to learn more about CH3NH2, its physical and chemical properties; the precautions you must observe; and its uses.

What Is CH3NH2?


CH3NH2, also known as methylamine, is an organic compound and the simplest major amine. Methylamine has a molecular weight of 31.057 g/mol and is derived from ammonia. Lastly, the methyl group replaces one hydrogen atom to convert ammonia to methylamine.

Stores sell CH3NH2 as an aqueous solution in ethanol, tetrahydrofuran, methanol, water, or gas in pressurized containers.

They use CH3NH2 as a building block to produce different compounds, such as cleaning agents, insecticides, rubber dyes, and many more commercial products.

The IUPAC name of CH3NH2 is methanamine. Other names include methylamine, aminomethane, and monomethylamine.

CH3NH2 Chemical Structure

The skeletal formula for methylamine is shown below [1]. You can view how the hydrogen atoms attach to the carbon and nitrogen atoms.

There are five hydrogen atoms, one carbon, and one nitrogen. That is why you can also write the formula as CH5N. 

The 3D image of the chemical structure of CH3NH2 or methylamine is presented below [2]. Moreover, the image shows the three hydrogen atoms attached to the carbon atom (gray color) and the two hydrogen atoms attached to the nitrogen atom (blue color). 

CH3NH2 Lewis Structure

The CH3NH2 Lewis structure has 14 valence electrons, with only two of those available for bonding with other compounds. Based on the formula, three hydrogen atoms are attached to the carbon atom (CH3) and two hydrogen atoms to the nitrogen atom (NH2).

To draw the Lewis structure of methylamine, follow the following steps:

  • Place two dots between the C and N atoms.
  • Since the C atom can accommodate six more electrons (as represented by dots), distribute them around the C atom.
  • Place three H atoms around the C atom.
  • And lastly, place 6 electrons (or dots) around the N
  • Then place the last two hydrogen atoms around it

See the drawing below. [3] Notice that you can replace the two dots as a line, and you’ll end up with the skeletal structure shown above.

Drawing of the Lewis Structure

To understand more about the CH3NH2 Lewis structure, watch the video below:

Is CH3NH2 an acid or base? CH3NH2 is a weak base. Methylamine is a lone pair donor when considering the definition of a Lewis base. 

Nitrogen’s (N) electrons attract the hydrogen proton from hydrochloric acid (HCl), leaving the anion chloride alone. CH3NH2 is also a Bronsted base because it is a proton acceptor.

Is CH3NH2 strong or weak? It is a weak base as an amine but a stronger base compared to ammonia (NH4). The ion formed after hydrogen (H+) bonding is stronger in methylamine than in ammonia

Examples of strong bases include the following:

  • Sodium hydroxide (NaOH),
  • Potassium hydroxide (KOH),
  • Lithium hydroxide (LiOH), and
  • Calcium hydroxide (Ca (OH)2).

With regards to polarity, is CH3NH2 polar or nonpolar? CH3NH2 or methylamine is a polar molecule because you can dissolve it in water and liquids. 

CH3NH2’s Physical and Chemical Properties

ch3nh2 lewis structure
a) Methylamine hydrogen bonding with another methylamine b) Methylamine hydrogen bonding with water

1. Appearance 

Anhydrous CH3NH2 appears as a colorless liquid or gas. Methylamine can appear colorless to yellow in aqueous gas solutions.

2. Odor 

CH3NH2 odor resembles that of ammonia, a pungent, fishy odor. If you open a methylamine container, the entire floor where you are could smell it. 

3. Chemical Formula

The chemical formula for methylamine is CH5N or CH3NH2. 

4. Boiling Point 

Methylamine’s liquid form boils at 20.3°F and turns to vapor that can evaporate quickly when uncovered. You should ventilate well the CH3NH2’s storage room as the vapor accumulates in low-lying areas because CH3NH2 is heavier than air.

5. Density 

CH3NH2 is denser than air and lighter than water. Methylamine’s density is 656.2 kg m-3 at 25° C. [4]. Moreover, methylamine’s density might change with temperature.

6. Combustion 

Methylamine easily ignites under most conditions. CH3NH2 containers may explode when you expose them to prolonged and extreme heat. Thus, the containers can rupture violently and get catapulted.

CH3NH2 is a highly flammable substance that you should carefully store and use. A well-ventilated area could help prevent spontaneous combustion.

You can refer to the storage and handling precautions discussed below.

7. Base Ionization Constant (Kb) 

The CH3NH2 Kb is 4.47 x 10.4 at 25°C. The Kb is the equilibrium constant achieved from the reaction of water and a weak base. This equilibrium constant helps determine the relative strengths of bases and acids. 

The formula used for any conjugate acid-base pair is KaKb=Kw, where Ka is the acid ionization constant and Kw is the ion-product constant of liquid water. Kw is defined as = [H3O+] [OH-]. [5]

8. CH3NH2 Hydrogen Bonding

CH3NH2 is capable of forming hydrogen bonding. This bond has a strength from 13 to 40 kJ/mole (kilojoules per mole). The hydrogen-nitrogen bonding is powerful with a dipole-dipole force.

9. Acid Dissociation Constant’s Negative Log (pKa)

The CH3NH2 pKa is 10.66 at 25°C. [6] This pKa value is the dissociation of CH3NH2 in water. A lower value would indicate that the acid could fully dissociate in water.

10. Shelf Life, Stability, and Storage

CH3NH2 (30 to 50%) is stable under recommended conditions. Thus, to maintain this stability, you should store the tightly closed containers at room temperature in a dry, cool, and well-ventilated area. 

Avoid storing methylamine with the following substances:

  • Mercury
  • Strong acids
  • Copper alloys
  • Oxidizing agents, such as peroxides, chlorates, bromine, chlorine, fluorine, permanganates
  • Zinc alloys
  • Nitromethanes
  • Galvanized surfaces
  • All combustibles, such as open flames and pressure; and
  • All other incompatible substances.

CH3NH2 is a dangerous fire hazard and is highly flammable, so follow the proper storage and handling correctly.

11. Flash Point

The flash point is the temperature at which a solid or liquid gives off vapor. So, this compound’s flash point is at -10 °C; 14 °F; 263 K. 

Precautions When Handling CH3NH2

ch3nh2 strong or weak

CH3NH2 is a toxic, corrosive, highly flammable, and irritating substance. Therefore, you have to be cautious in handling it. You must follow these precautions:

1. Wear Appropriate Personal Protective Equipment (PPE) 

When handling CH3NH2, wear appropriate protective gear as CH3NH2 can produce toxic oxide during combustion. Moreover, the oxide could irritate your skin and eyes. Also, the CH3NH2 conjugate acid component could be harmful to your skin.

Avoid contact with clothing, too, as inhalation or ingestion of Methylamine would not only irritate your skin and eyes but could also cause lung problems. You should also wear respirators when there is no proper ventilation.

If CH3NH2 contaminates your clothing, you have to remove it immediately and let a person well-acquainted with the substance wash it properly. 

PPE required are chemical-resistant gloves, chemical safety goggles or protective eyeglasses, footwear, headgear, face shield, and chemical-resistant appropriate protective clothing [7]. Do not use contact lenses too when handling methylamine. 

Safety experts recommend nitrile, neoprene, and Viton as protective materials due to their durability, water-proof properties, and excellent quality.

2. Wash Your Hands Thoroughly after Handling CH3NH2

You have to wash your hands or any exposed body parts thoroughly and immediately after handling CH3NH2. Wearing gloves and PPE can protect you, but you still have to take additional safety precautions by washing after handling.

Another safe option is to shower or take a bath if you want to be completely safe. Methylamine is a corrosive and toxic substance that you should protect yourself from and avoid at all costs.

3. Avoid Repeated Exposure

Your repeated exposure would increase your chances of inhaling methylamine. Moreover, repeated inhalation of CH3NH2 can irritate your throat and nose, causing wheezing and coughing. 

The substance can also irritate your lungs to cause bronchitis, dyspnea (shortness of breath), phlegm, and cough development. High methylamine exposure may also affect your liver.

The effect of CH3NH2 in pregnant women is the same, but the fetus may also be affected due to the mother’s unhealthy condition.

4. Use Explosion-Proof Equipment

Always use explosion-proof electrical fittings or equipment when handling, using, manufacturing, and storing CH3NH2. Observing proper protocol will prevent accidents or explosions that can harm people and the surrounding area.

The quality of equipment depends on the manufacturer’s reliability and efficiency. Never buy from untrusted and unauthorize sellers, no matter how cheap their product may be. Your safety comes first before the money.

5. Use Your Respirator Properly

You should use a Mine Safety and Health Administration (MSHA)/National Institute for Occupational Safety and Health (NIOSH)-approved full-facepiece respirator, most especially when there is a danger of being exposed to over 5 ppm of methylamine. This respirator type must have a NIOSH-approved canister or cartridge as well.

If expected exposure is 100 ppm, you should use NIOSH-approved self-contained breathing equipment with a full facepiece, an air cylinder with an emergency escape mode. The apparatus should also operate using positive-pressure or pressure-demand modes. These modes will allow you to respond quickly during emergencies.

Furthermore, expert staff should properly train you in using the respirator. You have to undergo respirator fit testing and medical exams too.

6. Know the CH3NH2 Exposure Limits

Knowing your Methylamine airborne exposure limits would help you avoid injury and illnesses. Here are the following recommended airborne permissible exposure limits (PEL):

  • American Conference of Governmental Industrial Hygienists (ACGIH) – 5 ppm averaged over an eight-hour work shift and 15 ppm as a short-term exposure limit.
  • National Institute for Occupational Safety and Health (NIOSH) – 10 ppm averaged over a ten-hour work shift. 
  • Occupational Safety and Health Administration (OSHA) – 10 ppm averaged over an eight-hour work shift.

The Lethal Dose (LD) and Lethal Concentration (LC) is 100 mg kg-1 (oral, rat) and 1860 ppm (mouse, 2 hours), respectively.

When you have accidentally ingested, inhaled, or come in contact with CH3NH2 lethal concentration, you will have to contact your health specialist immediately.

7. Learn How to Reduce CH3NH2 Exposure

You can reduce methylamine exposure through these steps:

  • Remember the post hazard warnings in the working area
  • Immediately submerge the affected or exposed body part in warm water
  • Use local ventilation in enclosed operations 
  • Wash thoroughly right after the end of a work shift
  • Use appropriate respirators when the area is not well-ventilated
  • Conduct proper orientation about methylamine’s safety and health hazards to all personnel

8. Emergency Facilities Must Be Provided

The company should provide emergency facilities, such as eye-wash fountains, showers, and containers for contaminated clothes or belongings. A person fully knowledgeable about methylamine should handle the contaminated items. 

Contaminated persons must change immediately into clean clothes and avoid further exposure. They should consult their health specialists to ensure that serious side effects will not occur.

Uses of CH3NH2 (Methylamine)

  1. Cleaning agents or solvents
  2. Pharmaceuticals
  3. Fuel additive
  4. Insecticides
  5. Rubber chemicals
  6. Dye processing chemicals
  7. Photographic processing chemicals
  8. Explosives
  9. Leather tanning chemicals
  10. Production of methamphetamine

The Drug Enforcement Administration in the United States has placed CH3NH2 in List 1 of controlled drugs due to the compound’s use in illicit methamphetamine production. 

Conclusion – What Is CH3NH2?

CH3NH2 is an organic compound that is colorless in gas form and colorless to yellow in aqueous solutions. It is also known as Methylamine, being a derivative of ammonia, the methyl group replacing one hydrogen atom. 

CH3NH2 or CH3NH2 has a 31.057 g/mol molecular weight and is soluble in ethanol, water, methanol, and tetrahydrofuran. 

Manufacturers sell methylamine in aqueous solutions or pressurized containers. Clients use CH3NH2 to build and synthesize various commercial compounds and products. Moreover, you can use Methylamine in many beneficial ways, but you should always be aware of its disadvantages and the danger the substance could inflict on your health.