Amines are organic compounds derived from ammonia (NH3) in which one or more hydrogen atoms are replaced by an alkyl or aryl group. The nitrogen atom keeps a lone pair of electrons, which makes amines basic and nucleophilic — the single property that drives most of their behavior, from accepting a proton to scrubbing acid gas out of a natural-gas stream. Amines are classified as primary, secondary, or tertiary depending on whether one, two, or three hydrogens of ammonia have been replaced by carbon groups.
This guide answers the textbook question first — what an amine is, how it is built, the types, and common examples — and then maps the industrial families that actually move at volume and how to source the right one. If you arrived for the chemistry, it is in the first sections. If you are buying amines by the drum, tote, or container, the application and sourcing map further down is the part that saves money.
What are amines?
An amine is a derivative of ammonia (NH3) in which at least one hydrogen has been replaced by a carbon-containing group — an alkyl group (as in methylamine, CH3NH2) or an aryl group (as in aniline, C6H5NH2). The defining feature of every amine is a nitrogen atom bonded to carbon and carrying a lone pair of electrons. That lone pair is what makes amines behave as bases and nucleophiles: it can accept a proton (H+) to form an ammonium ion, or attack an electron-poor center to form a new bond.
Amines are everywhere in chemistry and biology — amino acids, neurotransmitters such as dopamine and serotonin, and alkaloids such as caffeine all contain the amine group. Industrially, amines are workhorse intermediates and functional chemicals used in gas treating, epoxy curing, surfactants, agrochemicals, pharmaceuticals, and corrosion control.
Amine structure
The structure of an amine is built around a single nitrogen atom. Nitrogen has five valence electrons; in an amine it forms three sigma bonds and retains one non-bonding lone pair, giving it a pyramidal (roughly tetrahedral) geometry similar to ammonia. In a simple primary amine, R–NH2, the nitrogen is bonded to one carbon group and two hydrogens; the lone pair sits at the apex of the pyramid.
Two structural facts explain almost everything amines do:
- The lone pair drives basicity and nucleophilicity. Because the lone pair is available to bond a proton, aliphatic amines are slightly stronger bases than ammonia — the electron-donating alkyl groups push electron density toward nitrogen. Aromatic amines such as aniline are much weaker bases, because the nitrogen lone pair is delocalized into the aromatic ring and is less available to grab a proton.
- The N–H bonds set hydrogen bonding and reactivity. Primary and secondary amines have N–H bonds and form hydrogen bonds, raising their boiling points and water solubility relative to comparable hydrocarbons. Those N–H sites are also the reactive handles that let amines cure epoxies and form amides.
Types of amines
Amines are classified two ways. The first is by how many hydrogens of ammonia have been replaced by carbon groups — primary, secondary, or tertiary. The second is by the nature of the carbon group attached to nitrogen — aliphatic (alkyl chains) versus aromatic (attached directly to a benzene ring). A quaternary ammonium compound, where nitrogen carries four carbon groups and a positive charge, is a related cation rather than a neutral amine.
| Type | Structure | Carbon groups on N | Example | Typical use |
|---|---|---|---|---|
| Primary (1°) | R–NH2 | one | Methylamine; monoethanolamine (MEA); aniline | gas treating, surfactant feedstock, dyes |
| Secondary (2°) | R2NH | two | Dimethylamine; diethanolamine (DEA) | solvents, surfactants, agrochemicals |
| Tertiary (3°) | R3N | three | Trimethylamine; triethanolamine (TEA); MDEA | selective gas treating, cement grinding aids, catalysts |
| Aromatic | Ar–NH2 | N bonded to a ring | Aniline; toluidine | dyes, pigments, rubber chemicals, pharma intermediates |
| Quaternary ammonium | R4N+ | four (cationic) | Benzalkonium chloride | disinfectants, phase-transfer catalysts, fabric softeners |
The classification is about the nitrogen, not the carbon. A tertiary amine has three carbons on nitrogen and no N–H bond, which is why tertiary amines such as MDEA and TEA behave differently from primary amines such as MEA in the same job — they cannot form amides or cure epoxies the way an N–H-bearing amine does, but they still act as bases and catalysts.
Examples of amines
Common amines, from the simplest to the industrially important:
- Methylamine (CH3NH2) — the simplest primary amine; a building block for agrochemicals, pharmaceuticals, and surfactants.
- Aniline (C6H5NH2) — the archetypal aromatic amine; the foundation of dyes, polyurethanes (via MDI), and rubber chemicals.
- Ethanolamines — MEA, DEA, TEA — the alkanolamine family; water-soluble bases used in gas treating, metalworking fluids, and surfactants.
- Ethyleneamines — DETA, TETA — multiple reactive N–H sites; epoxy curing agents and chelants.
- Trimethylamine ((CH3)3N) — a simple tertiary amine; the “fishy” odor compound, used to make choline and quaternary ammonium salts.
- Biological amines — amino acids, dopamine, serotonin, histamine, and alkaloids such as caffeine and nicotine all contain the amine group.
What are amines used for?
Amines are used as bases, nucleophiles, and reactive intermediates across nearly every chemical industry. The largest-volume industrial uses are acid-gas treating, epoxy curing, surfactant manufacture, agrochemicals, and corrosion control. Below are the families that actually move at industrial scale — route your purchasing by these, not by the word “amine.”
| Family | Members we source | What the nitrogen does | Where it goes (industrial scale) |
|---|---|---|---|
| Alkanolamines | MEA, DEA, TEA, MDEA, DGA, DIPA, DMEA | base + hydroxyl (water-soluble, reversible acid-gas binding) | gas treating, metalworking, cement, surfactants, corrosion inhibition |
| Ethyleneamines | DETA, TETA, AEEA | multiple reactive N–H sites (crosslinking) | epoxy curing agents, lube/fuel additives, chelants, wet-strength resins |
| Specialty diamines | IPDA, MXDA | rigid, controlled-cure backbones | high-performance epoxy/polyurea coatings and composites |
Recommendation: name the member and grade, not “amine.” “Amine for gas treating” is a question; “MDEA, gas-treating grade” is an order. The family tells you the chemistry; the member tells you the job.
Gas treating — the container-scale play
The largest-volume amine use is acid-gas removal: scrubbing CO2 and H2S out of natural gas, refinery, and syngas streams. A water solution of the amine absorbs the acid gas in a contactor and releases it when heated, then recycles. The amine choice is a real engineering trade-off:
- MEA: highest absorption capacity per unit and lowest cost, but corrosive and non-selective (grabs both CO2 and H2S) and energy-intensive to regenerate.
- MDEA: selective for H2S over CO2, lower corrosivity, lower regeneration energy; the modern default for selective treating, often the higher-value buy.
- DGA: performs at low circulation rates and in cold climates.
This is where amines move by the tanker, and it is an oil & gas sourcing line. Recommendation: specify the treating amine to the gas analysis and the energy budget, not to the lowest price per pound — MEA’s cheap pound can cost more in corrosion and reboiler duty than MDEA’s.
Epoxy curing — ethyleneamines and specialty diamines
DETA, TETA, IPDA, and MXDA cure epoxy resins; the amine sets pot life, cure speed, and the final film’s heat and chemical resistance. IPDA and MXDA buy slower, more controlled cures for high-performance coatings and composites. Recommendation: match the amine to the cure schedule and service environment; the cheapest hardener can ruin an expensive resin system.
Metalworking, cement, water treatment, surfactants
TEA and DEA neutralize and buffer metalworking fluids and act as corrosion inhibitors; TEA and TIPA are cement grinding aids; neutralizing amines protect boiler and condensate lines in water treatment; MEA and DEA are feedstock for the amide surfactants (cocamide DEA/MEA) in cleaning products. Every one of these is a bulk, repeat, container-scale buy.
Safety — handle them as the corrosive bases they are
Alkanolamines and ethyleneamines are corrosive, alkaline, and sensitizing; many are combustible and several are skin and respiratory irritants. DEA in particular carries regulatory scrutiny in personal-care uses. Recommendation: treat amines as corrosives — appropriate PPE, compatible materials of construction (amines attack copper and its alloys), and segregation from acids and oxidizers. Always work from the current SDS for the specific amine and grade.
The trade-off worth stating plainly
There is no “best amine.” The properties that make MEA the cheapest, highest-capacity gas-treating amine (small, reactive, water-loving) are the same ones that make it corrosive and energy-hungry to regenerate; MDEA buys selectivity and lower operating cost at a higher purchase price. You are not buying “an amine”; you are buying the specific balance of basicity, reactivity, and selectivity your process needs.
How RawSource helps
RawSource is a sourcing company supplying industrial amines — alkanolamines such as monoethanolamine (MEA) and diethanolamine (DEA), ethyleneamines, and specialty diamines — in drum, tote, and container volumes. We don’t sit on inventory; we find and qualify the right amine for your process and source it to your written specification. If you need a gas-treating grade matched to your acid-gas load, an epoxy hardener for a defined cure schedule, or a metalworking-grade alkanolamine, tell us the amine, the grade, and the application, and we source it to spec with the certificate. Browse the amines & amides catalog or request a quote with your specification and target volume.
Frequently asked questions
What are amines? Amines are organic compounds derived from ammonia (NH3) in which one or more hydrogen atoms are replaced by an alkyl or aryl group. The nitrogen atom keeps a lone pair of electrons, which makes amines basic and nucleophilic.
What is the structure of an amine? An amine has a nitrogen atom bonded to one, two, or three carbon groups (and any remaining hydrogens), with a non-bonding lone pair on nitrogen. The geometry is pyramidal, like ammonia, and the lone pair is what gives amines their basicity and reactivity.
What are the 3 types of amines? Primary, secondary, and tertiary — defined by how many of ammonia’s hydrogens have been replaced by carbon groups (one, two, or three). The count changes basicity and reactivity, which is why MEA (primary), DEA (secondary), and MDEA/TEA (tertiary) behave differently in the same gas-treating job. Amines are also classified as aliphatic or aromatic depending on whether the carbon group is an alkyl chain or an aromatic ring.
What are some examples of amines? Methylamine and aniline are textbook examples; industrially important amines include the ethanolamines (MEA, DEA, TEA) and ethyleneamines (DETA, TETA). Amino acids, dopamine, serotonin, and caffeine are biological amines.
Are amines acids or bases? Amines are bases. The lone pair of electrons on nitrogen can accept a proton (H+) to form an ammonium ion. Aliphatic amines are slightly more basic than ammonia, while aromatic amines such as aniline are much weaker bases because the lone pair is delocalized into the ring.
What are amines used for? Amines are used as bases, nucleophiles, and reactive intermediates. The largest industrial uses are acid-gas treating (removing CO2 and H2S), epoxy curing, surfactant and amide manufacture, agrochemicals, corrosion inhibition, and pharmaceutical synthesis.
Which amine is used to remove CO2 and H2S from gas? Alkanolamines — most often MEA (high capacity, non-selective), MDEA (selective for H2S, lower energy), or DGA. The right one depends on the gas composition and the plant’s energy budget.
Are amines hazardous to handle? Yes — treat them as corrosive alkaline materials. They irritate skin and airways, attack copper alloys, and must be segregated from acids and oxidizers. Work from the SDS for the specific amine and grade.
