Description
Diethylamine is a colourless, strongly alkaline, fish odour liquid, and highly inflammable. It has an ammonia-like odour and is completely soluble in water. On burning, diethylamine releases ammonia, carbon monoxide, carbon dioxide, and nitrogen oxides. Diethylamine is used in the production of pesticides. It is used in a mixture for the production of DEET which goes into the repellents that are found readily in supermarkets for general use.
Chemical Properties
Diethylamine is a clear, alkaline liquid with a strong ammonia-like odor. The odor threshold for diethylamine is 0.14 ppm, which gives good warning of its presence. The boiling point is 56° C, and the vapor pressure is 195 mm Hg at 20° C (CRC Handbook, 1980). Diethylamine is soluble in water, ethanol, diethyl ether, acetone, aliphatic and aromatic hydrocarbons, mineral oils, and stearic and oleic acids (NIOSH, 1979). The hydrochloride salt of diethylamine is a crystalline solid with a melting point of 226° C and a boiling point range of 320° to 330° C (Merck, 1996). The salt is soluble in water, ethanol, and chloroform but is practically insoluble in diethyl ether. Diethylamine (pkb=3.0) is more alkaline than ammonia (pkb=4.76) (Beard and Noe, 1981). The more alkaline the compound, the lower the pkb.
Physical properties
Colorless liquid with a fishy, ammonia-like odor. Experimentally determined detection and recognition odor threshold concentrations were 60 μg/m3 (20 ppbv) and 180 μg/m3 (60 ppbv), respectively (Hellman and Small, 1974). Diethylamine is a very strong base in aqueous solution (pKb = 3.0). Its chemistry is governed by the unshared electron pair on the nitrogen, thus it tends to react with acids to form salts.
Occurrence
Diethylamine occurs in low concentrations in food and other biological materials.
Concentrations (in p.p.m.) in fresh products include: spinach (15), apples (3), butterbeans
(2.4), shelled peas (0.1), bean salad (1.5) and red cabbage (2.4) (HSDB
1989). Pickled vegetables contain 0-3.2 p.p.m. diethylamine while concentrations
(in p.p.m.) in other materials include herring (0-5.2), barley (5.7), hops (3.1), boiled
beef (2), tobacco leaf (0.1-35) and cigarette smoke concentrate (0-0.4). Interest in
the occurrence of diethylamine in foods arises in part because of its possible formation
of a carcinogenic N-nitroso derivative (Neurath et al 1977). Diethylamine has
been reported in the exhaust from a gasoline engine (Hampton et al 1982).
Uses
Diethylamine is manufactured by heating ethyl chloride and
alcoholic ammonia under pressure or by hydrogenation of
aziridines in the presence of catalysts. DEA is used as a
solvent, as a rubber accelerator, in the organic synthesis of
resins, dyes, pesticides, and pharmaceuticals, in electroplating,
and as a polymerization inhibitor. Other
applications include uses as a corrosion inhibitor. It was
reported noneffective as a skin depigmentator.
Production Methods
Diethylamine is produced using the three methods also used for the manufacture of ethylamine with very slight modification.
Diethylamine Synthesis
1. N,N-Diethyl-3-methylbenzamide + Ethylene Glycol + NaOH + Heat
2. Ethylchloride + Ammonia (forms diethylamine HCL)
3. Ethanol + Ammonia + Sulfuric Acid
The most widely used method is the passing of ammonia and ethanol over a catalyst such as alumina or silica (Schweizer et al 1978). Diethylamine can be separated from the mixture by selective distillations and extractions.
Definition
ChEBI: Diethylamine is a secondary aliphatic amine where both N-substituents are ethyl. It is a conjugate base of a diethylammonium.
General Description
Diethylamine appears as a clear colorless liquid with an ammonia-like odor. Density 5.9 lb / gal. Flash point -15 °F. A respiratory irritant. Corrosive to the eyes and skin. Vapors heavier than air. Toxic oxides of nitrogen produced during combustion.
Air & Water Reactions
Highly flammable. Soluble in water. Sensitive to heat. May be sensitive to prolonged exposure to air.
Reactivity Profile
It is incompatible with several chemical substances such as strong oxidisers, acids, cellulose nitrate, some metals, and dicyanofuroxan. N-nitrosamines, many of which are known to be potent carcinogens, may be formed when diethylamine comes in contact with nitrous acid, nitrates, or atmospheres with high nitrous oxide concentrations.
Health Hazard
Diethylamine can be harmful if it is inhaled, swallowed, or in contact with skin.
Vapors can irritate the eyes and cause irritation of the respiratory tract, leading to
coughing and chest pain. Liquid diethylamine can cause severe burns to the eyes
and skin. Vision became misty and halos appeared several hours after workmen
were exposed to the vapors of amines such as diethylamine (Grant 1986). The
edema of the corneal epithelium, which is principally responsible for the disturbances
in vision, clears after one or more days, depending on the severity of
exposure. Photophobia and discomfort from roughness of the corneal surface also
can occur after greater exposure to the amine.
Flammability and Explosibility
Highly flammable
Chemical Reactivity
Reactivity with Water No reaction; Reactivity with Common Materials: No hazardous reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Flush with water; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.
Industrial uses
Diethylamine, like many of the other short chain aliphatic amines, has achieved
widespread industrial use as an intermediate in the manufacture of a number of
commercial products. Among these are included insecticides, pharmaceuticals,
textile finishing agents, and corrosion inhibitors (Hawley 1981; Schweizer et al
1978). It is used as a polymerization inhibitor and/or catalyst in the polymer
industry and in the manufacture of surfactants and rubber processing accelerators.
This amine also is useful as a depilatory agent for animal skins, as a selective
solvent for the removal of impurities from oils, fats, and waxes, and as a flotation
agent in the petroleum industry (NIOSH/OSHA 1981; HSDB 1989).
Industrial uses
Hydrogen sulfide (H2S) poses significant hazards in oil and gas drilling, including corrosion of drilling equipment, environmental risks, and threats to personnel safety. Diethylamine serves as an amine-based H2S scavenger in aqueous drilling fluids[1]. Furthermore, it exhibited a noncorrosive nature, with corrosion rates nearing zero.
Toxicology
Exposure to low vapor concentrations are reported to transiently impair vision in humans (reduction of sensitivity to light): no-effect threshold 0.022 – 0.028 mL/m3 ( 0.08mg/m3 ). The odor threshold in air is ca. 0.02 – 0.3 mL/m3 ( 0.9 mg/m3 ). Transient physiological effects in rats after 90-d exposure to vapors were reported to already be visible at 0.37 – 4.19 mg/m3 with no effects at 0.05 mg/m3 , but with morphological, apparently reversible changes in the lung and cerebral neurons at the highest concentration. On the other hand, 50 mL/m3 (150 mg/m3 ) was the lowest concentration to show mild, but signifi- cant effects in the lung and liver of rabbits on prolonged inhalation. There were no visible signs of toxicity following exposure of rats to 25 mL/m3 (75 mg/m3 ) for 120 d, but a moderate, bronchiolar hyperplasia of lymphoid cells. It was assumed that diethylamine may exert a certain neurotoxic effect, which, however, was not confirmed by others.
Safety Profile
Moderately toxic by
ingestion, inhalation, and skin contact. A
skin and severe eye irritant. Exposure to
strong vapor can cause severe cough and
chest pains. Contact with liquid can damage
eyes, possibly permanently; contact with
skin causes necrosis and vesciculation. A
very dangerous fire hazard when exposed to
heat, flame, or oxidizers. To fight fire, use
alcohol foam, CO2, dry chemical. Explodes
on contact with dicyanofurazan. Violent
reaction with sulfuric acid. Ignites on
contact with cellulose nitrate of sufficiently
high surface area. When heated to
decomposition it emits toxic fumes of NOx.
See also MINES.
Potential Exposure
Tumorigen,Mutagen. Primary Irritant. Diethylamine (DEA) is used in themanufacture of the following chemicals: diethyldithiocarbamate and thiurams (rubber processing accelerators);diethylaminoethanol (medicinal intermediate); diethylaminopropylamine (epoxy curing agent); N,N-diethyl-m-toluamide and other pesticides; and 2-diethylaminoethylmethacrylate. Itis used in the manufacture of several drugs.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.Medical observation is recommended for 24-48 h afterbreathing overexposure, as pulmonary edema may bedelayed. As first aid for pulmonary edema, a doctor orauthorized paramedic may consider administering a corticosteroid spray.
Carcinogenicity
No evidence of mutagenicity was seen
in Ames bacterial assays.8 Diethylamine has
an ammonia-like odor that is detectable at
0.13ppm.
The 2003 ACGIH threshold limit valuetime-
weighted average (TLV-TWA) for
diethylamine is 5ppm (15mg/m3) with
a short-term excursion limit of 15ppm
(45mg/m3) and an A4-not classifiable as a
human carcinogen designation; there is a notation
for skin absorption.
Environmental Fate
Photolytic. Low et al. (1991) reported that the photooxidation of aqueous secondary amine
solutions by UV light in the presence of titanium dioxide resulted in the formation of ammonium
and nitrate ions.
Chemical/Physical. Diethylamine reacted with NOx in the dark forming diethylnitrosamine. In
an outdoor chamber, photooxidation by natural sunlight yielded the following products:
diethylnitramine, diethylformamide, diethylacetamide, ethylacetamide, ozone, acetaldehyde, and
peroxyacetyl nitrate (Pitts et al., 1978).
Reacts with mineral acids forming water-soluble salts (Morrison and Boyd, 1971).
Metabolism
Little information is available regarding the metabolism of diethylamine. The
amine can be readily absorbed from the respiratory and gastrointestinal tract. It has
been reported that following oral administration of diethylamine hydrochloride to
humans, much of the amine was recovered in the urine (Beard and Noe 1978). This
suggests that it is not readily metabolized and, therefore, may not be a substrate for
monoamine oxidase. When administered intraperitoneally to rats, it was moderately
inhibitory with respect to liver monoamine oxidase (Valiev 1974). Diethylamine
may serve as a precursor for the formation of the reportedly carcinogenic
N-nitrosoamines and, indeed, when a diethylamine containing liquid was examined
for nitrosation reactions under simulated conditions of the human stomach,
N-nitrosodiethylamine was formed (Ziebarth 1985).
storage
Diethylamine should be protected from physical damage. It should be kept stored in a
cool, dry, well-ventilated location, away from incompatible chemical substances and away
from fi re hazard and smoking areas. The containers should be bonded and grounded for
transfer to avoid static sparks. Storage and use areas should be no smoking areas.
Shipping
This compound requires a shipping label of“FLAMMABLE LIQUID.” It falls in Hazard Class 3 andPacking Group II.
Purification Methods
Dry diethylamine with LiAlH4 or KOH pellets. Reflux with, and distil it from, BaO or KOH. Convert it to the p-toluenesulfonamide and crystallise to constant melting point from dry pet ether (b 90-120o), then hydrolyse with HCl, excess NaOH is added, and the amine is passed through a column of activated alumina. Redistil the amine and dry it with activated alumina before use [Swift J Am Chem Soc 64 115 1942]. [Beilstein 4 III 313.] § A polystyrene diethylaminomethyl supported version is commercially available.
Incompatibilities
Forms explosive mixture with air. Mayaccumulate static electrical charges, and may cause ignitionof its vapors. Violent reaction with strong oxidizers, strongacids, cellulose nitrate. Incompatible with organic anhydrides, isocyanates, vinyl acetate, acrylates, substitutedallyls, alkylene oxides, epichlorohydrin, ketones, aldehydes,alcohols, glycols, mercury, phenols, cresols, caprolactumsolution. Attacks aluminum, copper, lead, tin, zinc, andalloys.
Toxics Screening Level
The initial threshold screening level (ITSL) for diethylamine is 150 μg/m3 based on an 8 hour averaging time.
Precautions
Occupational workers and users should be very careful during the use and chemical management
of diethylamine. Workers should wear impervious protective clothing, including
boots, gloves, a laboratory coat, apron or coveralls, as appropriate, to prevent skin contact. The chemical is very hazardous, corrosive, and harmful, and is a very flammable liquid
and vapor. Exposures to vapor may cause fl ash fi re. It causes burns and adverse effects
to the cardiovascular system. Workers should use chemical safety goggles and a full-face
shield to avoid splashing of the chemical substance. An eye-wash fountain and quickdrench
facilities in the work area should be maintained by the chemical management unit.
References
[1] Ahmed, A., Elkatatny, S., & Onaizi, S. (2025). Evaluating Diethylamine and Triethylamine as Alternative Amine-Based H2S Scavengers for Safe and Efficient Drilling in Sour Conditions. ACS Omega, 10 29, 31492–31500.
https://doi.org/10.1021/acsomega.5c01472
