Difference between revisions of "Methylamine"

Revision as of 13:51, 12 July 2020

Methylamine or methanamine is a colorless gas with a strong fishy odor, having the formula CH₃NH₂ (sometimes shortened to MeNH₂). It is an organic compound, the simplest primary amine.

Properties

Chemical

Methylamine reacts with acids to form methylammonium salts, such as methylammmonium chloride (or methylamine hydrochloride):

CH₃NH₂ + HCl → CH₃NH₃Cl

Physical

Methylamine is a colorless gas, heavier than air with a strong fish-like odor. It is very soluble in water and various organic solvents.

Availability

Methylamine is sold by various chemical suppliers, either as compressed gas in tanks or as salt, solid or as solution.

Legality

In US, methylamine and its salts are DEA List I chemicals, due to their use in the production of methamphetamine, and as such cannot be purchased freely.

Many other countries have similar restrictions.

Preparation

There are several routes to methylamine.

The industrial process involves the reaction of methanol with anhydrous ammonia, in the presence of a drying catalyst, such as silica gel or more effective, a zeolite based catalyst. The reaction takes place at high temperatures, and dimethylamine and trimethylamine are also produced as side products with the latter being the most favoured by the reaction kinetics. Methylamine can be extracted from the mixture via either fractional distillation or other convenient methods.^[1]

The most convenient route is by refluxing a mixture of formaldehyde and ammonium chloride, at around 104 °C.

NH₄Cl + 2 H₂CO → CH₃NH₂·HCl + HCOOH

Both reagents are readily available in most places and the final product of the reaction is methylammonium chloride, which is solid and non-volatile, which makes the reaction safe. However, extracting the methylamine hydrochloride from the product proves frustrating, though it's perfectly possible.^[2]

To obtain freebase methylamine, MeNH₂·HCl is reacted with a base, such as sodium hydroxide.

Hofmann rearrangement of acetamide (made from the dehydration of ammonium acetate) will give methylamine.

Hydrolysis of methyl isocyanate will also yield methylamine. However, the precursor is very toxic, which makes the reaction dangerous and impractical.

Another route involves the reduction of nitromethane with Zn/HCl.

Refluxing sulfamic acid with methanol for several hours yields ammonium methyl sulfate, which rearranges at high temperature to form methylamine sulfate.

H₂NSO₃H + CH₃OH → CH₃SO₄NH₄

CH₃SO₄NH₄ → CH₃NH₃·HSO₄

Projects

• Make methylamommium halides
• Make methylammonium nitrate
• Make methylammonium perchlorate
• Make Metol

Handling

Safety

Methylamine is toxic and proper protection should be worn when handling the product.

Storage

Methylamine is best stored as a salt.

Anhydrous methylamine can be stored in compressed cylinders.

Disposal

Methylamine salts pose little danger to environment and (generally) don't require special disposal.

References

1. ↑ http://www.sciencedirect.com/science/article/pii/S0920586197000035
2. ↑ http://www.youtube.com/watch?v=xIWfnQr7168

Relevant Sciencemadness threads

• methylamine
• Good way to Methylamine HCl?
• Methylamine problem