Article No : a10_001 Ethanolamines and Propanolamines MATTHIAS FRAUENKRON, BASF Aktiengesellschaft, Ludwigshafen, Germany JOHANN-PETER MELDER, BASF Aktiengesellschaft, Ludwigshafen, Germany GU¨ NTHER RUIDER, BASF Aktiengesellschaft, Ludwigshafen, Germany ROLAND ROSSBACHER, BASF Aktiengesellschaft, Ludwigshafen, Germany HARTMUT HO¨ KE, Weinheim, Germany 1. Introduction........................ 405 4.3. Quality Specifications................. 417 2. Ethanolamines ...................... 405 4.4. Uses .............................. 417 2.1. Properties ......................... 406 5. N-Alkylated Propanolamines and 2.1.1. Physical Properties ................... 406 3-Alkoxypropylamines ................ 418 2.1.2. Chemical Properties................... 406 5.1. Properties ......................... 418 2.2. Production ......................... 407 5.1.1. Physical Properties ................... 418 2.3. Quality Specifications................. 408 5.1.2. Chemical Properties................... 418 2.4. Uses .............................. 408 5.2. Production ......................... 418 2.5. Economic Aspects ................... 410 5.3. Quality Specifications................. 420 3. N-Alkylated Ethanolamines ............ 410 5.4. Uses and Economic Aspects ............ 420 3.1. Properties ......................... 411 6. Storage and Transportation............ 421 3.1.1. Physical Properties ................... 411 7. Environmental Protection ............. 421 3.1.2. Chemical Properties................... 411 8. Toxicology and Occupational Health ..... 421 3.2. Production ......................... 411 8.1. General Aspects..................... 421 3.3. Quality Specifications................. 413 8.2. Ethanolamines ...................... 424 3.4. Uses and Economic Aspects ............ 413 8.3. N-Alkyl- und N-Arylethanolamines ....... 425 4. Isopropanolamines................... 414 8.4. Propanolamines ..................... 427 4.1. Properties ......................... 414 References ......................... 428 4.1.1. Physical Properties ................... 414 4.1.2. Chemical Properties................... 415 4.2. Production ......................... 416 0 1. Introduction (DEA; 2,2 -iminodiethanol), and triethanola- mine [102-71-6](3) (TEA; 2,20,200-nitrilotrietha- Amino alcohols have been prepared industrially nol) can be regarded as derivatives of ammonia in since the 1930s. However, large-scale production which one, two, or three hydrogen atoms have started only after 1945, when alkoxylation with been replaced by a CH2CH2OH group. ethylene oxide and propylene oxide replaced the older chlorohydrin route. In industry, amino alcohols are usually designated as alkanola- mines. Ethanolamines (aminoethanols) and pro- panolamines (aminopropanols) are by far the most important compounds of this group. Both are used widely in the manufacture of surfactants and in gas purification [1–6]. 2. Ethanolamines Ethanolamines were prepared in 1860 by WURTZ from ethylene chlorohydrin and aqueous Monoethanolamine [141-43-5](1) (MEA; 2- ammonia [7]. It was only toward the end of the aminoethanol), diethanolamine [111-42-2](2) 19th century that an ethanolamine mixture was Ó 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/14356007.a10_001 406 Ethanolamines and Propanolamines Vol. 13 separated into its mono-, di-, and triethanolamine 2.1.2. Chemical Properties components; this was achieved by fractional distillation. Because of their basic amino group and the hydro- Ethanolamines were not available commer- xyl group, ethanolamines have chemical properties cially before the early 1930s; they assumed resembling those of both amines and alcohols. They steadily growing commercial importance as in- form salts with acids, and the hydroxyl group termediates only after 1945, because of the large- permits ester formation. When mono- and dietha- scale production of ethylene oxide. Since the nolamine react with organic acids, salt formation mid-1970s, production of very pure, colorless always takes place in preference to ester formation. triethanolamine in industrial quantities has been With weak inorganic acids, e.g., H2SandCO2, possible [117–119]. All ethanolamines can now thermally unstable salts are formed in aqueous be obtained economically in very pure form. solution. This reaction of ethanolamines is the basis The most important uses of ethanolamines are for their application in the purification of acidic in the production of emulsifiers, detergent raw natural gas, refinery gas, and synthesis gas [1], [8]. materials, and textile chemicals; in gas purifica- In the absence of water, monoethanolamine and tion processes; in cement production, as milling diethanolamine react with CO2 to form carbamates: additives; and as building blocks for agrochemi- þ ! cals [120]. Monoethanolamine is an important 2 HOCH2CH2NHR CO2 HOCH2CH2CH2NRCOOH Á feedstock for the production of ethylenediamine RHNCH2CH2OH and ethylenimine. R ¼ HorCH2CH2OH Triethanolamine does not form a carbamate. 2.1. Properties By metal-catalyzed amination, the hydroxyl group of monoethanolamine can be replaced by 2.1.1. Physical Properties an amino group to form ethyleneamines such as ethylenediamine [107-15-3], diethylenetriamine Monoethanolamine and triethanolamine are vis- [111-40-0], piperazine [110-85-0], and ami- cous, colorless, clear, hygroscopic liquids at noethylethanolamine [111-41-1] [9], [10]: room temperature; diethanolamine is a crystal- line solid. All ethanolamines absorb water and carbon dioxide from the air and are infinitely miscible with water and alcohols. The freezing points of all ethanolamines can be lowered considerably by the addition of water. Some physical properties of ethanolamines are listed in Table 1. Table 1. Physical properties of ethanolamines a Compound Mr mp, Cbp Density r Heat of vaporization Specific heat cp Cubic expansion (101.3 kPa), C (20 C), g/cm3 (101.3 kPa), kJ/kg kJ kgÀ1 KÀ1 coefficient, KÀ1 Monoethanolamine 61.08 10.53 170.3 1.0160 848.1 2.72 7.78Â10À4 Diethanolamine 105.14 28.0 268.5 1.0912 (30 C) 638.4 2.73 5.86Â10À4 Triethanolamine 149.19 21.6 336.1 1.1248 517.8 2.33 4.82Â10À4 Compound Viscosity 20 Surface tension Flash point,b Ignition temperature,c, Temperature class d nD (20 C), mPa Á s (20 C), N/m C C Monoethanolamine 23.2 1.4544 0.049 94.5 410 T2 Diethanolamine 389 (30 C) 1.4747 0.0477 176 365 T2 Triethanolamine 930 1.4852 0.0484 192 325 T2 a According to DIN 53 217. b According to DIN 51 758. c According to DIN 51 794. d According to VDE 0165. Ethanolamines do not belong to any hazard class according to VbF (regulation governing flammable liquids). Vol. 13 Ethanolamines and Propanolamines 407 Considerable quantities of monoethanola- Reaction of triethanolamine with ethylene ox- mine are converted into ethylenimine (aziridine ide gives unstable alkaline quaternary compounds [151-56-4]) by adding sulfuric acid and cyclizing and the corresponding stable ethers [122]. For the hydrogensulfate with sodium hydroxide or by example, undistilled triethanolamine prepared using heterogeneous catalysts [121] (! Aziri- from mono- or diethanolamine always contains dines) [11], [12]: some triethanolamine monoglycol ether [16]. Mono- or diethanolamine can also be used as the amine component in aminoalkylation, the so- called Mannich reaction, which is very important in the biosynthesis of many alkaloids [17]. As primary and secondary amines, monoetha- nolamine and diethanolamine also react with acids or acid chlorides to form amides. The amine first reacts with the acid, e.g., stearic acid, to form a salt, which can be dehydrated to the amide by heating: NH2CH2CH2OHþC17H35COOH !NH2CH2CH2OH Á C17H35COOH ! À À À þ HOCH2CH2 NH CO C17H35COOH H2O Catalytic dehydrogenation of diethanolamine leads to iminodiacetic acid, an important build- When the ethanolamides of fatty acids are ing block for agrochemicals [120]. heated at fairly high temperature with removal -Nitrosamines can be formed by treating of water, oxazolines are formed: N diethanolamine or, under suitable conditions, triethanolamine with nitrous acid, nitrites, or oxides of nitrogen. Animal experiments have shown that N-nitrosamines are carcinogenic [18]. Formaldehyde reacts with monoethanolamine and diethanolamine to form hydroxymethyl compounds, which can be reduced to the N- methyl derivatives [14] (see Section 3.2). Monoethanolamine reacts with carbon disul- fide to form 2-mercaptothiazoline [ ] [15]: 96-53-7 Monoethanolamine and triethanolamine can form complexes with transition metal ions (e.g., chromium, copper, nickel, cobalt, and iron); some of these complexes are water-soluble [123–125]. The hydroxyl groups of ethanolamines can be replaced with chlorine by reaction with thionyl 2.2. Production chloride or phosphorus pentachloride. The chlor- oethylamines formed are hazardous because of their Ethanolamines are produced on an industrial skin toxicity. For example, tris(2-chloroethyl)amine scale exclusively by reaction of ethylene oxide has been used as a gas in warfare (N-lost). Bis(2- with excess ammonia, this excess being consid- chloroethyl)amine is obtained in good yield by erable in some cases [19]. reaction of diethanolamine with thionyl chloride: The reaction of ethylene oxide with ammonia takes place slowly and is accelerated by water. Anhydrous procedures employ a fixed-bed cata- lyst consisting of an organic ion-exchange resin or thermally more stable acidic inorganic clays or zeolites [20–23]. 408 Ethanolamines and Propanolamines Vol. 13 In all conventional processes, reaction takes place