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| HS Code | 809109 |
| Name | Methylamine |
| Chemical Formula | CH3NH2 |
| Molecular Weight | 31.057 g/mol |
| Cas Registry Number | 74-89-5 |
| Un Number | 1061 |
| Appearance | Colorless gas |
| Odor | Fishy, ammoniacal |
| Melting Point | -93.4 °C |
| Boiling Point | -6.6 °C |
| Liquid Density | 0.656 g/cm3 at -10 °C |
| Vapor Density Relative To Air | 1.07 |
| Solubility In Water | Miscible |
| Pka Of Conjugate Acid | 10.62 |
| Flash Point | -60 °C |
| Autoignition Temperature | 430 °C |
| Explosive Limits In Air | 4.9% to 20.8% by volume |
As an accredited Methylamine factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Methylamine is packaged as a liquefied gas in steel cylinders or drums, typically in quantities of 50 kg or 450 kg. |
| Container Loading (20′ FCL) | 20′ FCL loading of Methylamine involves securing compatible drums/IBCs, dangerous goods segregation, ventilation, labeling, and spill containment. |
| Shipping | Methylamine is shipped as a hazardous material, often as a liquefied compressed gas or flammable solution. It requires approved pressure-rated cylinders or containers, proper hazard labeling for flammability and toxicity, secure ventilation, and segregation from oxidizers, acids, and foodstuffs. Transport must comply with international dangerous goods regulations, including documentation and emergency response information. |
| Storage | Methylamine should be stored in a cool, well-ventilated area away from heat, flames, and direct sunlight. Anhydrous methylamine requires approved pressurized cylinders or cryogenic containers; aqueous solutions need corrosion-resistant, tightly sealed vessels. Keep containers upright and isolated from oxidizers, acids, and incompatible materials. Use leak detection and proper labeling, with emergency ventilation and spill containment available. |
| Shelf Life | Methylamine has a shelf life of up to two years when stored sealed, cool, dry, and away from oxidizers. |
Methylamine is metered into a closed reactor with carbon disulfide and aqueous sodium hydroxide to yield sodium N-methyldithiocarbamate, the active substance in metam sodium soil fumigant. The reaction follows CH3NH2 + CS2 + NaOH → CH3NHCS2Na + H2O; production units hold the monomethylamine-to-carbon-disulfide-to-sodium-hydroxide molar feed at 1.00:1.02:1.05 to consume carbon disulfide and maintain residual free alkalinity in the concentrate. The exotherm is controlled in a jacketed 316L stirred vessel with brine cooling to keep the reaction mass between 20°C and 30°C. Concentrate pH is held between 9.5 and 10.5 because acidification below pH 9.0 accelerates conversion to methyl isothiocyanate inside the storage tank. The commercial aqueous solution is standardized at 32–42 wt% metam sodium, with sodium hydroxide and water making up the balance.
Field application is performed by shank injection or drip tape. The formulated product is diluted into irrigation water immediately before injection; soil temperature at 15–25 cm depth should be above 5°C to avoid slow diffusion of methyl isothiocyanate. The treated zone is sealed by compaction or plastic film to retain methyl isothiocyanate in the root zone for 48–96 h. Buffer zones, personal protective equipment and re-entry intervals are specified in the product label under 40 CFR Part 156 and state-level fumigant management plans. For EU exports, registration under Regulation (EU) 540/2011 requires residue data for the methyl isothiocyanate metabolite. Terminal products include 42% aqueous metam sodium and 54% metam potassium. Storage failure modes observed in production and distribution include hydrogen sulfide and carbon disulfide pressure build-up when the tank is contaminated with acid, and crystallisation when the product is held below 0°C.
The synthesis of N-methylglucamine from D-glucose and monomethylamine proceeds through reductive amination over a supported nickel catalyst. Continuous hydrogenation lines are run with a D-glucose-to-monomethylamine molar feed ratio of 1.0:1.2 to 1.0:1.6; the excess methylamine suppresses formation of sorbitol through direct glucose hydrogenation. Hydrogen partial pressure is maintained at 3.0–6.0 MPa, with reaction temperature between 65°C and 85°C in a high-pressure autoclave fitted with catalyst retention screens. The crude product is filtered to reduce nickel carry-over, decolorized with activated carbon, and crystallized from aqueous methanol. Final product conforms to the USP-NF Meglumine monograph and the corresponding European Pharmacopoeia monograph; assay is not less than 99.0% on the dried basis, loss on drying is not more than 1.0%, and residual methylamine is controlled below 0.1% by headspace gas chromatography.
Meglumine is used to form water-soluble salts of radiocontrast agents such as diatrizoic acid. The terminal injectable formulation must meet 21 CFR 211 current good manufacturing practice for finished pharmaceuticals and USP <788> particulate matter limits for injections. In manufacturing, meglumine is dissolved in Water for Injection at 40–50°C before addition of diatrizoic acid; pH adjustment of the final solution to 6.0–7.5 is critical because free methylamine release at higher pH can create amine odour and reduce assay. The heat sterilisation step is validated at 121°C for 15 min or equivalent F0. If the meglumine feedstock contains reducing sugar impurities, Maillard browning increases platinum-cobalt color above the injectable specification. Published data for specific industrial-scale batch records is limited, but chromatographic purity limits are standardized in the pharmacopeia.
In gas-treating applications, monomethylamine is first converted to N-methyldiethanolamine through reaction with ethylene oxide in an aqueous pressure loop. The design stoichiometry requires two moles of ethylene oxide per mole of methylamine; operating units maintain a methylamine-to-ethylene oxide feed ratio between 1:2.0 and 1:2.1. Water content of 10–20 wt% is kept in the reactor to absorb reaction heat and limit oligomerisation. Temperature is held between 120°C and 170°C, and reactor pressure is controlled at 1.0–2.5 MPa. After reaction, unreacted ethylene oxide is stripped under vacuum, and the crude N-methyldiethanolamine is purified through a two-column distillation sequence to a final strength of ≥99.0 wt%. Residual monomethylamine and ethylene oxide are held below 0.2 wt% and 0.01 wt% respectively to prevent downstream corrosion and off-spec amine color.
Terminal use in gas treating takes place in a countercurrent absorber at natural-gas pipeline pressure, typically 3.0–8.0 MPa, with an aqueous N-methyldiethanolamine concentration of 40–50 wt%. Lean amine is charged at 35–45°C. The regenerator reboiler is operated on low-pressure steam of 0.4–0.6 MPa, and reboiler temperature is held below 130°C to prevent thermal degradation of the tertiary amine. Acid-gas loading in the rich amine is typically controlled at 0.35–0.50 mol CO2/mol amine, while treated gas is dried and tested to pipeline specifications for H2S below 4 ppmv and CO2 below 2 mol%. Heat-stable salt contamination from oxygen ingress or amine degradation products is limited to ≤1.0 wt% to avoid foaming and fouling of plate-and-frame exchangers. Analytical control includes titration for amine strength and density or refractive index for lean/rich loading. Cross-border shipments of N-methyldiethanolamine require REACH registration with an exposure scenario restricted to industrial use.
Gamma-butyrolactone and monomethylamine are reacted to produce N-methylpyrrolidone in a continuous high-pressure reactor. The molar feed ratio of gamma-butyrolactone to monomethylamine is kept between 1:1.05 and 1:1.20; the slight methylamine excess ensures lactone ring opening reaches conversion above 98%. Typical reactor conditions are 250–300°C at 2.0–5.0 MPa. The crude N-methylpyrrolidone is dehydrated and purified by distillation; battery-grade material is further treated by ion exchange and submicron filtration to remove residual gamma-butyrolactone, water, and metal ions. The specification for lithium-ion electrode coating uses gas chromatography assay ≥99.9%, Karl Fischer moisture ≤0.02% by ASTM E203, and platinum-cobalt color ≤10 by ASTM D1209-21.
In the cathode coating process, N-methylpyrrolidone dissolves polyvinylidene fluoride binder at a typical ratio of 8–12 parts NMP per 1 part PVDF by weight. The resulting slurry viscosity is adjusted to 1,500–8,000 mPa·s depending on NCM or LFP solid loading and electrode target thickness. The solvent is removed in a slot-die drying tunnel; condensation and distillation recovery can return 85–95% of the N-methylpyrrolidone, while non-condensable organics are destroyed in a thermal oxidizer at 850–950°C. Process air must be monitored because N-methylpyrrolidone vapour is classified under REACH as a suspected reproductive toxin and is subject to occupational exposure limits. A comparative specification matrix is provided below.
| Parameter | Industrial grade | Battery grade |
|---|---|---|
| NMP assay, GC | ≥99.5% | ≥99.9% |
| Water, ASTM E203 | ≤0.05% | ≤0.02% |
| Color, ASTM D1209-21 | ≤20 APHA | ≤10 APHA |
| Metal ions, ICP-MS | ≤1 ppm | ≤0.1 ppm |
Chloromethylated styrene-divinylbenzene copolymer beads are aminated with monomethylamine to produce a weakly basic anion exchange resin. The reaction is conducted in a stirred pressure reactor with methanol or aqueous methanol as swelling solvent at 40–60°C for 4–8 h. Because monomethylamine is a primary amine, the first substitution generates a secondary benzylamine; a second substitution at the same nitrogen can proceed to a tertiary amine, so the ratio of chloromethyl groups to methylamine is kept between 1:1.5 and 1:3.0 to control the mix of secondary and tertiary exchange sites. Residual chloromethyl groups are verified by chloride release after hydrolysis. The final resin is washed with hot deionized water and methanol to remove leachable amine, then classified to a bead size range of 0.3–1.2 mm.
Terminal use in industrial demineralization trains places the weak base anion unit after a strong acid cation exchanger. The resin adsorbs free mineral acidity such as HCl or H2SO4 at pH 0–7, and is regenerated with sodium hydroxide at 2–4% concentration. Operating temperature is limited to ≤60°C for the benzylamine functional group; higher temperatures accelerate amine loss into treated water and reduce operating capacity. Product compliance for drinking water contact requires testing under NSF/ANSI 61 or the equivalent national regulation in the destination market. In food processing, resin suppliers may refer to 21 CFR 173.25 for ion-exchange resins used in process water. End products include portable deionization cartridges, large vessel resin fills for power plant condensate polishing, and acid scavenging resins for hydrometallurgical circuits.
Manufacture of N-methyl carbamate insecticides begins with conversion of monomethylamine and phosgene to methyl isocyanate. The reaction CH3NH2 + COCl2 → CH3NCO + 2HCl is run in a continuous Hastelloy C-276 tubular reactor with excess phosgene maintained at a methylamine-to-phosgene molar ratio of 1:1.05 to 1:1.20 to prevent formation of methylamine hydrochloride and reduce urea by-products. The reaction mass is held at 120–160°C in an inert solvent such as chlorobenzene. Methyl isocyanate product is condensed and stored under dry nitrogen at 0–5°C for short-term intermediate use only. On-site consumption is the standard operating boundary; intermediate transfer lines are designed with double containment and continuous gas detection.
Downstream carbamylation is commonly carried out with α-naphthol to yield carbaryl, or with oxime substrates to yield aldicarb-type compounds. The carbamylation reaction is catalysed by a tertiary amine at 40–80°C, with the methyl isocyanate-to-phenol/oxime molar ratio maintained close to 1:1. Reaction yield and purity are monitored by HPLC, with residual methyl isocyanate quenched before downstream processing. The terminal formulated products include carbaryl dusts and slurries, methomyl soluble concentrates, and aldicarb granules; these require pesticide registration under 40 CFR Part 152 in the United States and under Regulation (EU) 1107/2009 in the EU. Process safety and toxicity constraints are governed by the EPA Risk Management Plan 40 CFR Part 68 and OSHA Process Safety Management 29 CFR 1910.119. Published engineering data on specific plant yields is limited because of security and hazard controls, but the operating ranges above align with publicly available process safety guidance and carbamate registration dossiers.
Carbonylation of monomethylamine yields N-methylformamide, a polar aprotic industrial solvent. The reaction is performed in a bubble column or continuous stirred autoclave using carbon monoxide at 2.0–8.0 MPa and 80–120°C with a sodium methoxide catalyst. The carbon monoxide-to-methylamine molar feed ratio is held between 1.0:1.0 and 1.5:1.0 to maintain conversion above 90%. The crude product is distilled to remove unreacted methylamine and methanol; final N-methylformamide purity is ≥99.0%, water ≤0.1%, and platinum-cobalt color ≤20 by ASTM D1209-21. N-methylformamide is used in polyacrylonitrile precursor spinning for carbon fiber, where residual water must be below 0.05% to avoid filament defects. Terminal industrial batches are shipped under REACH registration for solvent use, with moisture controlled by ASTM E203 Karl Fischer titration.
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Methylamine is the lowest molecular weight primary aliphatic amine, derived structurally from ammonia by substitution of one hydrogen with a methyl group. Commercial supply is organized by concentration model rather than by discrete product architecture: anhydrous liquefied gas with a minimum assay of 99.5 wt%, and aqueous solutions near 30 wt%, 40 wt%, 50 wt%, and 60 wt% monomethylamine. The molecular weight is 31.06 g/mol; the normal boiling point is -6.3 °C at 101.3 kPa, and the pKa of the protonated cation is 10.63 at 25 °C. Industrial synthesis proceeds by continuous vapor-phase reaction of methanol and ammonia over an amorphous silica-alumina catalyst at approximately 350–450 °C and 1.5–3.0 MPa. The product distribution from the fixed-bed reactor includes dimethylamine and trimethylamine, so the ammonia-to-methanol molar ratio is maintained between 1.2 and 2.0 in published plant configurations to favour mono-substitution. Methanol conversion per pass is typically limited to 15–25%; unreacted methanol and excess ammonia are recovered by distillation and recycled. The reaction is exothermic and temperature control near the catalyst inlet is maintained within ±5 °C because selectivity to trimethylamine increases at higher operating temperatures.
Aqueous grades are manufactured by absorption into demineralized water, not by simple dilution with potable water. Process water conductivity is maintained below 5 µS/cm to reduce metal ion contamination. The density of 40% methylamine solution is approximately 0.90 g/cm³ at 20 °C, measured by ASTM D4052-22. The 60% grade exhibits a higher vapour pressure and is more prone to evaporation from open vessels. Specification sheets from merchant suppliers typically report assay, water content, ammonia, dimethylamine, and trimethylamine. Assay is determined by aqueous acid-base titration with standard hydrochloric acid; organic impurities are determined by gas chromatography using flame-ionization detection. Product models are shipped under UN 1061 for anhydrous methylamine and UN 1235 for aqueous solutions, with hazard classes for flammable gas and flammable liquid respectively.
The principal specification distinction arises from physical state and vapour pressure. Anhydrous methylamine is stored and shipped as a liquefied compressed gas and requires a tight water limit to prevent hydrate formation and internal corrosion. Aqueous solutions are controlled instead for total amine strength and for carbonate formation after exposure to atmospheric carbon dioxide. Commercial limits vary by producer, but the values in the following table are representative of merchant technical data sheets. The water and ammonia limits are not equivalent between anhydrous and aqueous grades because water is a defined solvent component in aqueous formulations, not an impurity.
| Grade | CAS | Assay limit | Water limit | Ammonia limit | Dimethylamine limit | Transport classification |
|---|---|---|---|---|---|---|
| Anhydrous methylamine | 74-89-5 | 99.5 wt% min | 0.10 wt% max | 0.10 wt% max | 0.10 wt% max | UN 1061 |
| 40% aqueous solution | 74-89-5 | 39.5–41.0 wt% | 58.5–60.5 wt% | 0.10 wt% max | 0.10 wt% max | UN 1235 |
| 60% aqueous solution | 74-89-5 | 59.0–61.0 wt% | 39.0–41.0 wt% | 0.15 wt% max | 0.15 wt% max | UN 1235 |
Ammonia is a critical impurity in methylamine supplied for pharmaceutical alkylation because residual ammonia competes for electrophilic substrates and increases the formation of secondary amides. A typical 40% aqueous grade may carry ammonia below 0.10 wt%, whereas an anhydrous grade may permit 0.05 wt% maximum in high-purity merchant supply. Methanol is limited to 0.10 wt% in some anhydrous specifications because it can act as a competing nucleophile or solvent contaminant. Iron content is controlled below 1.0 mg/kg in grades intended for electronics or pharmaceutical intermediates, measured by inductively coupled plasma optical emission spectrometry after acid digestion. Because methylamine is hygroscopic and carbon dioxide-sensitive, sampling of anhydrous product requires closed-loop sample cylinders with stainless steel valves, and aqueous product is sampled from a closed loop with an air-free vessel to avoid contamination.
On a continuous methylamine train, the pressure distillation column is typically a packed column with structured packing equivalent to 20–30 theoretical stages, operated at a reflux ratio between 1.5 and 3.0. The overhead condenser uses chilled water or glycol; anhydrous product is accumulated in carbon steel pressure receivers with relief valves set at 1.6 MPa at 50 °C. In aqueous production, the absorber column is fed with demineralized water at a mass ratio near 2.3 kg water per kg anhydrous methylamine for 40% solution. Published data for specific proprietary catalyst formulations is limited; the general silica-alumina system is associated with periodic air regeneration and gradual loss of acid sites through coking when the methanol-to-ammonia ratio exceeds the recommended upper band.
In primary amine form, methylamine contains a reactive nitrogen-hydrogen bond that participates in Schiff-base formation, nucleophilic addition to carbonyl groups, and amide synthesis with acid chlorides. Dimethylamine, as a secondary amine, has two alkyl substituents and cannot form primary amide intermediates in the same manner; trimethylamine, as a tertiary amine, is limited to quaternization and acid-neutralization reactions under ordinary process conditions. The pKa values differentiate these bases: 10.63 for methylamine, 10.73 for dimethylamine, and 9.81 for trimethylamine. Although the basicity difference between methylamine and dimethylamine is small, the steric environment at nitrogen changes nucleophilicity in aprotic solvents. For reactions requiring a primary nitrogen centre, such as the formation of N-methylamides from carboxylic acid chlorides or the synthesis of N-methylpyrrolidone from γ-butyrolactone, methylamine is selected. In solvent-grade production, methylamine is consumed with carbon monoxide and methanol to give N,N-dimethylformamide, but dimethylamine competes as a reactant depending on the carbonyl source and catalyst. The vapour pressure of methylamine is approximately 304 kPa at 20 °C, compared with approximately 170 kPa for dimethylamine at the same temperature, which shifts head-space handling requirements for pressurized reactors.
| Property | Methylamine | Dimethylamine | Trimethylamine | Ethylamine |
|---|---|---|---|---|
| Molecular weight | 31.06 g/mol | 45.08 g/mol | 59.11 g/mol | 45.08 g/mol |
| Normal boiling point | -6.3 °C | 7.0 °C | 2.9 °C | 16.6 °C |
| pKa of protonated form at 25 °C | 10.63 | 10.73 | 9.81 | 10.70 |
| Functional class | Primary amine | Secondary amine | Tertiary amine | Primary amine |
| Common commercial forms | Anhydrous gas, 40–60% aqueous | Anhydrous gas, 40 wt% aqueous | Anhydrous gas, 25–45% aqueous | Anhydrous gas, 70% aqueous |
| Typical downstream product | N-methylpyrrolidone, metam sodium | Dimethylformamide, dimethylacetamide | Choline chloride, quaternary ammonium salts | Ethylamine derivatives for herbicides |
The separation of methylamine from dimethylamine and trimethylamine is energy-intensive because the three amines are close-boiling and form azeotropes with water. Extractive distillation with water or caustic is used; in some plants, anhydrous methylamine is taken overhead from a pressure column while dimethylamine is recovered as a side stream. The relative volatility of methylamine to dimethylamine under typical pressure column conditions is low enough to require structured packing and high reflux ratios; published values for the relative volatility of the anhydrous pair are in the range of 1.4–1.7. This contrasts with ethylamine, whose normal boiling point of 16.6 °C permits ordinary distillation at less severe pressure and lower cooling requirement.
Agrochemical manufacturing consumes methylamine in the preparation of metam sodium through reaction with carbon disulfide and sodium hydroxide in aqueous medium. The reaction is conducted under temperature control near 25–40 °C to avoid an uncontrolled exotherm; the resulting product is typically stabilized as a 42% aqueous solution. Methylamine is also used in the synthesis of N-methylcarbamate insecticides, where the amine is converted to methyl isocyanate and subsequently condensed with naphthol intermediates. In pharmaceutical synthesis, methylamine participates in reductive amination sequences and in the preparation of alkaloid-like nitrogen heterocycles; published data for specific active pharmaceutical ingredient yields is limited where proprietary process routes are involved. The compound is a precursor to N-methylpyrrolidone via reaction with γ-butyrolactone at elevated temperature and pressure, and the resulting aprotic solvent is used in lithium-ion battery electrode coating slurries, polyvinylidene fluoride dissolution, and petrochemical extraction. In these downstream applications, residual dimethylamine and trimethylamine are controlled because secondary and tertiary amine impurities can alter N-methylpyrrolidone purity and downstream battery slurry stability.
In methylamine-based pharmaceutical reductive amination, reaction configuration is usually a stainless steel stirred reactor with a hydrogen cap, a catalyst basket or slurry phase, and a cooling jacket. The exotherm is managed by controlled addition of methylamine as a solution or gas sparge; pH is maintained between 8.0 and 9.5 by buffering. Residual methylamine in the crude product is removed by acid-base extraction and vacuum stripping, with final limits set by the relevant pharmacopoeial monograph for the active ingredient. The use of methylamine in batch hydrogenation requires reactor pressure ratings above the vapour pressure of water at operating temperature, often 0.7–1.0 MPa at 80–100 °C. These operating conditions are general process ranges; exact parameters are route-specific and generally not published in merchant literature.
Anhydrous methylamine is stored as a liquefied compressed gas in horizontal cylindrical pressure vessels fabricated from carbon steel with a design pressure rated at 1.8 MPa at 55 °C. Piping and valve trim avoid copper, brass, zinc, and galvanized steel because the amine corrodes these metals and forms coloured complexes. Stainless steel 316L or high-density polyethylene is used for aqueous transfer lines; nitrogen blanketing is required when handling aqueous methylamine in storage tanks to limit carbonate formation from atmospheric carbon dioxide. Centrifugal pumps with double mechanical seals and magnetically coupled positive-displacement pumps are employed for liquid transfer in bulk loading racks. Filling of tank trucks and ISO containers is performed through closed-loop vapour return lines, with the receiving vessel grounded and inerted. Aqueous methylamine at 40% has a closed-cup flash point near -13 °C determined by ASTM D56-22 or ISO 3679:2022; the anhydrous material is flammable with a lower explosive limit of 4.9 vol% in air. Storage areas are classified under NFPA 497 for flammable gas or liquid, with continuous gas detection set to alarm at 10% of the lower explosive limit.
With respect to product substitution, methylamine differs from ammonia in its higher organic substitution reactivity; ammonia has a pKa of 9.25 and a normal boiling point of -33.3 °C, making it less nucleophilic in non-aqueous condensations and more difficult to handle as a liquefied gas because of its lower boiling point. Methylamine is a stronger base and a better leaving-group precursor in Mannich reactions than ammonia. Compared with ethylamine, methylamine provides a shorter alkyl chain architecture and higher vapour pressure, which influences solvent selection and reactor pressure rating. In processes where lower volatility and a liquid phase are required at ambient pressure, ethylamine or isopropylamine may be considered; however, they introduce different steric profiles and solubility limitations. Published data for direct substitution benefits is limited where multiphase reaction kinetics are not disclosed by the technology licensor.
Operational boundaries for methylamine include drying of piping with dry nitrogen before opening where ambient relative humidity exceeds 60%, and exclusion of oxidizing agents such as chlorine, bromine, peroxides, and concentrated nitric acid. Contact with strong acids produces rapid neutralization and heat release; spills are diluted with water and neutralized with dilute acetic acid under vapour suppression. Aqueous methylamine solutions absorb carbon dioxide from air, forming methylammonium carbamate, which can raise viscosity and precipitate in low-temperature equipment. Closed handling, inert gas padding, and moisture exclusion are therefore specified for both anhydrous and aqueous grades in bulk storage and feed systems.
