Dimethylamine Dimethylamine
Structural formula
| Business number | 03J5 |
|---|---|
| Molecular formula | C2H7N |
| Molecular weight | 45 |
| label |
N-methylmethylamine, Aliphatic carboxylic acids and their derivatives |
Numbering system
CAS number:124-40-3
MDL number:MFCD00008288
EINECS number:204-697-4
RTECS number:IP8750000
BRN number:605257
PubChem number:24857770
Physical property data
1. Characteristics: colorless gas, with a high concentration smell of ammonia, and with low concentration a smell of rotten fish. [1]
2. Melting point (℃): -92.2[2]
3. Boiling point (℃): 7.0[3]
4. Relative density (water = 1): 0.68[4]
5. Relative vapor Density (air=1): 1.6[5]
6. Saturated vapor pressure (kPa): 203 (25℃)[6]
7. Heat of combustion (kJ/mol): -1743.5 (liquid); -1768.9 (gas) [7]
8. Critical temperature (℃ ): 164.5[8]
9. Critical pressure (MPa): 5.31[9]
10. Octanol /Water partition coefficient: -0.38[10]
11. Flash point (℃): 20 (CC)[11]
12. Ignition temperature (℃): 400[12]
13. Explosion upper limit (%): 14.4[13]
14. Lower explosion limit (%): 2.8[14]
15. Solubility: easily soluble in water, soluble in ethanol and ether. [15]
16. Flash point (ºC): 430
17. Heat of evaporation (KJ/mol, 6.84ºC): 26.50
18. Heat of formation (KJ/mol, gas): -27.6
19. Specific heat capacity (KJ/(kg·K), 7.29ºC, liquid, constant pressure): 3.04
20.pKa (25ºC, water): 10.732
Toxicological data
1. Acute toxicity[16]
LD50: 698mg/kg (rat oral); 316mg/kg (mouse oral Oral); 240mg/kg (rabbit oral)
LC50: 8354mg/m3; 4540ppm (rat inhalation, 6h); 4725ppm (mouse inhalation, 2h)
2. Irritation [17] Rabbit eye: 50mg (5min), causing irritation.
3. Subacute and chronic toxicity[18] Rats exposed to 2~4mg/m3, 3 weeks , 3 hours a day, cerebral cortical activity disorder is seen; 2~7mg/m3, 7 months, 3 hours a day, 6 days a week, causes reversible dysfunction and mild damage to the lungs, liver, and kidneys.
4. Mutagenicity[19] Cytogenetic analysis: Rats inhaled 50μg/m3. Sister chromatid exchange: hamster ovary 500μmol/L
Ecological data
1. Ecotoxicity[20]
LC50: 30~50mg/L (24h) (Black-spotted yarrow); 120mg/L (96h) (rainbow trout); 210mg/L (96h) (guppy)
EC50: 9mg/L (96h) (green algae); 30mg/L (96h) (single cell Green algae); 26.8mg/L (15min) (photobacteria, Microtox toxicity test)
2. Biodegradability[21]
Aerobic biodegradation (h): 2~79
Anaerobic biodegradation (h): 8~316
3. Non-biodegradability[22]
Photooxidation half-life in air (h): 0.892~9.2
Molecular structure data
1. Molar refractive index: 14.90
2. Molar volume (cm3/mol): 70.3
3. Isotonic specific volume (90.2K ): 139.6
4. Surface tension (dyne/cm): 15.5
5. Polarizability (10-24cm3): 5.91
Compute chemical data
1. Reference value for hydrophobic parameter calculation (XlogP): -0.2
2. Number of hydrogen bond donors: 1
3. Number of hydrogen bond acceptors: 1
4. Number of rotatable chemical bonds: 0
5. Number of tautomers: none
6. Topological molecule polar surface area 12
7. Number of heavy atoms: 3
8. Surface charge: 0
9. Complexity: 2.8
10. Number of isotope atoms: 0
11. Determine the number of atomic stereocenters: 0
12. Uncertain number of atomic stereocenters: 0
13. Determine the number of chemical bond stereocenters: 0
14. Number of uncertain chemical bond stereocenters: 0
15. Number of covalent bond units: 1
Properties and stability
1. Basic properties: It is weakly alkaline and forms salts easily soluble in water with inorganic acids. Its vapor can form an explosive mixture with air, with an explosion limit of 2.8%-14.4%. Low flash point, avoid direct sunlight and keep away from fire sources. Corrosive to copper, copper alloys, aluminum, tin, zinc, etc.
2. The chemical properties are typical of secondary amines. For example:
① The aqueous solution is alkaline and forms salts with a certain melting point with inorganic acids, organic acids, and acidic aromatic nitro compounds. Form complex salts with heavy metal compounds.
② Acylation reaction occurs with acid chloride, acid anhydride, etc. to generate N-substituted amide. Salts formed with aliphatic carboxylic acids also form N-substituted amides after dehydration. Reacts with sulfonyl chloride and aromatic sulfonyl chloride to generate the corresponding N-substituted sulfonamide.
③ When reacting with hydrocarbylation reagents such as halogenated hydrocarbons, alcohols, phenols or amine salts, the hydrogen atoms on the nitrogen are replaced by hydrocarbon groups.
④ Addition reaction can occur with cyanic acid, carbon disulfide, nitrile, epoxy, etc.
⑤ Secondary amine reacts with aliphatic or aromatic aldehydes and dehydrates to form Schiff base. Reacts with formaldehyde in alkaline solution to generate bis(dialkylamino)methane. Or react dimethylamine hydrochloride, formaldehyde with a compound containing active hydrogen (Mannich reaction) to generate a compound in which the active hydrogen is replaced by dimethylaminomethyl. Dimethylamine reacts with aldehydes in the presence of potassium carbonate to generate ditertiary amine, which is distilled to obtain α,β-unsaturated amine (enamine).
⑥ Secondary amines are relatively stable to acidic potassium permanganate and are easily oxidized in alkaline potassium permanganate. It reacts with persulfuric acid, hydrogen peroxide, and organic peroxyacid to obtain amine oxygen-containing compounds. For example, it reacts with hydrogen peroxide to form dialkylhydroxylamine. After oxidation of benzoic acid, o-benzoic acid derivatives are generated.
⑦ Reacts with nitrous acid to generate nitrosamines.
⑧ Reacts with Grignard reagent to generate hydrocarbons.
In addition, dimethylamine undergoes thermal cracking at 420~440°C to generate methylamine, methane, hydrogen, etc. It can also decompose under ultraviolet light irradiation to generate gases such as methane and polymer substances.
3. Dimethylamine solution is strongly irritating to the skin and mucous membranes. Long-term contact with high-concentration vapor can cause symptoms such as dermatitis, conjunctivitis, blindness, and suffocation. The olfactory threshold concentration is 165mg/m3. TJ 36-79 stipulates that the maximum allowable concentration in workshop air is 10 mg/m3. The oral LD50 in rats is 698 mg/kg. The LD50 of rabbit intravenous injection is 4000mg/kg.
4. Stability[23] Stable
5. Incompatible substances[24] Strong oxidants, acids, halogens
6. Polymerization hazard[25] No polymerization
Storage method
Storage Precautions[26] Stored in a cool, ventilated warehouse dedicated to flammable gases. Keep away from fire and heat sources. The storage temperature should not exceed 30℃. Keep container tightly sealed. They should be stored separately from oxidants, acids, and halogens, and avoid mixed storage. Use explosion-proof lighting and ventilation facilities. It is prohibited to use mechanical equipment and tools that are prone to sparks. The storage area should be equipped with leakage emergency response equipment.
Synthesis method
1. Mix methanol and ammonia in a certain proportion, at a certain temperature and pressure, using activated alumina as a catalyst, to synthesize a mixture of mono, di, and trimethylamine, and then undergo heat exchange, condensation, deamination, extraction, After dehydration and separation, the finished product of dimethylamine is obtained.
Refining method: often contains methylamine , trimethylamine, ammonia and methanol and other impurities. It can be refined by pressure distillation. Or dimethylamine hydrochloride is repeatedly recrystallized with ethanol until its melting point reaches 171°C. Use potassium hydroxide to free dimethylamine, then use dry ice-diethyl ether to cool the liquid, and dry the solid potassium hydroxide and sodium fluorenone to obtain pure dimethylamine. Other refining methods include reacting dimethylamine with p-toluenesulfonic acid to convert it into p-toluenesulfonamide. Recrystallize with 70% ethanol until the melting point reaches 80~80.5°C, then hydrolyze with hydrochloric acid to generate dimethylamine hydrochloride, and then process it according to the above method.
2. It is weakly alkaline, It forms easily water-soluble salts with inorganic acids.
Purpose
1. Mainly used as rubber vulcanization accelerator, leather dehairing agent, medicine (antibiotics), pesticides (thiram, dipyramide, benzofuron and other herbicides), textile industry solvents, dyes, explosives, propellants And raw materials for organic intermediates such as dimethylhydrazine, N,N-dimethylformamide. Among them, the dimethylamine consumed in the production of dimethylformamide accounts for 44.7% of the total consumption, the consumption of pesticide production accounts for 38.9%, and the consumption of medicine and other production accounts for 16.4%. Also used as plant fungicides, herbicides, insecticides and acid gas absorbers. When depilating leather with lime, dimethylamine sulfate can be used as an accelerator.
2. Used in organic synthesis and precipitation of zinc hydroxide, etc. [27]
Organic acids produce salts that are easily soluble in water.
Purpose
1. Mainly used as rubber vulcanization accelerator, leather dehairing agent, medicine (antibiotics), pesticides (thiram, dipyramide, benzofuron and other herbicides), textile industry solvents, dyes, explosives, propellants And raw materials for organic intermediates such as dimethylhydrazine, N,N-dimethylformamide. Among them, the dimethylamine consumed in the production of dimethylformamide accounts for 44.7% of the total consumption, the consumption of pesticide production accounts for 38.9%, and the consumption of medicine and other production accounts for 16.4%. Also used as plant fungicides, herbicides, insecticides and acid gas absorbers. When depilating leather with lime, dimethylamine sulfate can be used as an accelerator.
2. Used in organic synthesis and precipitation of zinc hydroxide, etc. [27]
