Difference between revisions of "Methylamine"
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| pKa = | | pKa = | ||
| pKb = 3.36 | | pKb = 3.36 | ||
| − | | Solubility = 1 | + | | Solubility = 1.008 g/L (at 20 °C) |
| SolubleOther = Miscible in [[diethyl ether]]<br>Soluble in [[acetone]], [[benzene]], [[ethanol]], [[methanol]], [[Tetrahydrofuran|THF]] | | SolubleOther = Miscible in [[diethyl ether]]<br>Soluble in [[acetone]], [[benzene]], [[ethanol]], [[methanol]], [[Tetrahydrofuran|THF]] | ||
| Solvent = | | Solvent = | ||
| Line 90: | Line 90: | ||
| AutoignitionPt = 430 | | AutoignitionPt = 430 | ||
| ExploLimits = 4.9–20.7% | | ExploLimits = 4.9–20.7% | ||
| − | | ExternalMSDS = | + | | ExternalMSDS = [https://www.docdroid.net/fJCS5WK/methylamine-sa.pdf.html Sigma-Aldrich] |
| FlashPt = −10 °C | | FlashPt = −10 °C | ||
| LD50 = 100 mg kg<sup>−1</sup> (oral, rat) | | LD50 = 100 mg kg<sup>−1</sup> (oral, rat) | ||
| − | | LC50 = | + | | LC50 = 1,860 ppm (mouse, 2 hr) |
| MainHazards = Toxic | | MainHazards = Toxic | ||
| NFPA-F = | | NFPA-F = | ||
| Line 105: | Line 105: | ||
| OtherFunction = | | OtherFunction = | ||
| OtherFunction_label = | | OtherFunction_label = | ||
| − | | OtherCompounds = [[Ammonia]] | + | | OtherCompounds = [[Ammonia]]<br>[[Dimethylamine]]<br>[[Trimethylamine]] |
}} | }} | ||
}} | }} | ||
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Methylamine reacts with acids to form methylammonium salts, such as methylammmonium chloride (or methylamine hydrochloride): | Methylamine reacts with acids to form methylammonium salts, such as methylammmonium chloride (or methylamine hydrochloride): | ||
| − | :CH<sub>3</sub>NH<sub>2</sub> + HCl → CH<sub>3</sub>NH<sub>3</sub>Cl | + | : CH<sub>3</sub>NH<sub>2</sub> + HCl → CH<sub>3</sub>NH<sub>3</sub>Cl |
===Physical=== | ===Physical=== | ||
| Line 120: | Line 120: | ||
==Availability== | ==Availability== | ||
| − | Methylamine is sold by various chemical suppliers. | + | Methylamine is sold by various chemical suppliers, either as compressed gas in tanks or as salt, solid or as solution. |
===Legality=== | ===Legality=== | ||
| Line 134: | Line 134: | ||
The most convenient route is by refluxing a mixture of [[formaldehyde]] and [[ammonium chloride]], at around 104 °C. | The most convenient route is by refluxing a mixture of [[formaldehyde]] and [[ammonium chloride]], at around 104 °C. | ||
| − | :NH<sub>4</sub>Cl + 2 H<sub>2</sub>CO → CH<sub>3</sub>NH<sub>2</sub>·HCl + HCOOH | + | : NH<sub>4</sub>Cl + 2 H<sub>2</sub>CO → CH<sub>3</sub>NH<sub>2</sub>·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.<ref>http://www.youtube.com/watch?v=xIWfnQr7168</ref> | 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.<ref>http://www.youtube.com/watch?v=xIWfnQr7168</ref> | ||
| Line 140: | Line 140: | ||
To obtain freebase methylamine, MeNH<sub>2</sub>·HCl is reacted with a base, such as sodium hydroxide. | To obtain freebase methylamine, MeNH<sub>2</sub>·HCl is reacted with a base, such as sodium hydroxide. | ||
| − | Hofmann rearrangement of | + | 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. | 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 [[Zinc|Zn]]/[[Hydrogen chloride|HCl]]. | Another route involves the reduction of [[nitromethane]] with [[Zinc|Zn]]/[[Hydrogen chloride|HCl]]. | ||
| + | |||
| + | Refluxing [[sulfamic acid]] with [[methanol]] for several hours yields ammonium methyl sulfate, which rearranges at high temperature to form methylamine sulfate. | ||
| + | |||
| + | :H<sub>2</sub>NSO<sub>3</sub>H + CH<sub>3</sub>OH → CH<sub>3</sub>SO<sub>4</sub>NH<sub>4</sub> | ||
| + | :CH<sub>3</sub>SO<sub>4</sub>NH<sub>4</sub> → CH<sub>3</sub>NH<sub>3</sub>·HSO<sub>4</sub> | ||
==Projects== | ==Projects== | ||
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Methylamine is best stored as a salt. | Methylamine is best stored as a salt. | ||
| − | Anhydrous methylamine can be stored in | + | Anhydrous methylamine can be stored in gas cylinders. |
===Disposal=== | ===Disposal=== | ||
| Line 176: | Line 181: | ||
[[Category:Amines]] | [[Category:Amines]] | ||
[[Category:Alkylamines]] | [[Category:Alkylamines]] | ||
| + | [[Category:Primary amines]] | ||
[[Category:Bases]] | [[Category:Bases]] | ||
| + | [[Category:Organic bases]] | ||
[[Category:Lewis bases]] | [[Category:Lewis bases]] | ||
[[Category:Materials unstable in basic solution]] | [[Category:Materials unstable in basic solution]] | ||
[[Category:Foul smelling compounds]] | [[Category:Foul smelling compounds]] | ||
[[Category:DEA List I chemicals]] | [[Category:DEA List I chemicals]] | ||
Latest revision as of 21:56, 21 October 2020
| Names | |
|---|---|
| IUPAC name
Methanamine
| |
| Other names
Aminomethane
Carbinamine Glycamine Mercurialin Monomethylamine MeNH2 MMA | |
| Properties | |
| CH5N CH3NH2 | |
| Molar mass | 31.06 g/mol |
| Appearance | Colorless gas |
| Odor | Fishy, ammoniacal |
| Density | 1.4 g/l (gas) 0.6624 g/cm3 (liquid, at 25 °C) |
| Melting point | −93.10 °C (−135.58 °F; 180.05 K) |
| Boiling point | −6.6 °C (20.1 °F; 266.5 K) |
| 1.008 g/L (at 20 °C) | |
| Solubility | Miscible in diethyl ether Soluble in acetone, benzene, ethanol, methanol, THF |
| Thermochemistry | |
| Std enthalpy of
formation (ΔfH |
−23.5 kJ mol−1 |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | −10 °C |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
100 mg kg−1 (oral, rat) |
| LC50 (Median concentration)
|
1,860 ppm (mouse, 2 hr) |
| Related compounds | |
| Related compounds
|
Ammonia Dimethylamine Trimethylamine |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
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.
Contents
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 gas cylinders.
Disposal
Methylamine salts pose little danger to environment and (generally) don't require special disposal.
References
- ↑ http://www.sciencedirect.com/science/article/pii/S0920586197000035
- ↑ http://www.youtube.com/watch?v=xIWfnQr7168
