Fatty amines
A fatty amine is a mostly primary amine with a long-chain unbranched alkyl chain of eight or more carbon atoms . Fatty amines are oleochemicals because they are made from vegetable or animal fats or oils.
Fatty amines particularly often contain alkyl radicals with a length of 12 to 18 carbon atoms, since they are mainly synthesized from the corresponding fatty acids . Oleylamine is derived from an unsaturated fatty acid - oleic acid - and contains an alkenyl radical instead of an alkyl radical . Technically produced fatty amines are often mixtures of several primary amines with varying lengths of the alkyl radicals.
Manufacturing
Fatty amines are mainly synthesized by reacting fatty acids with ammonia and then hydrogenating the resulting nitriles .
In the first step, a fatty acid (usually a mixture of several fatty acids, RCOOH) reacts with ammonia (NH 3 ). This reaction takes place at over 250 ° C and in the presence of a metal oxide catalyst , for example aluminum oxide (Al 2 O 3 ). The corresponding fatty acid nitrile (RC≡N) is formed with elimination of water :
- RCOOH + NH 3 → RC≡N + 2 H 2 O
The nitrile is then catalytically hydrogenated. Raney nickel is mostly used as the catalyst . As long as there is excess ammonia, the primary amine (RCH 2 NH 2 ) is formed:
- RCN + 2 H 2 → RCH 2 NH 2
If no ammonia is present in the hydrogenation, secondary and tertiary amines can also be formed:
- 2 RCN + 4 H 2 → (RCH 2 ) 2 NH + NH 3
- 3 RCN + 6 H 2 → (RCH 2 ) 3 N + 2 NH 3
Further procedures
The fatty amines can also, starting from fatty alcohols , be synthesized at 210-260 ° C. in the presence of dehydrogenation catalysts with ammonia or short-chain alkyl or dialkyl amines .
properties
Depending on the length of the alkyl radical, the respective fatty amine is liquid, pasty or solid. Fatty amines are poorly soluble in water, but have good solubility in organic solvents . When they come into contact with acids , they form salts .
Examples
The table shows some examples of fatty amines with their names, which are derived from the associated fatty acids.
| C atoms: double bonds | Surname | Gross formula |
|---|---|---|
| 8-0 | 1-octylamine | C 8 H 17 NH 2 |
| 10-0 | 1-decylamine | C 10 H 21 NH 2 |
| 12: 0 | 1-dodecylamine | C 12 H 25 NH 2 |
| 14: 0 | 1-tetradecylamine | C 14 H 29 NH 2 |
| 16: 0 | 1-hexadecylamine | C 16 H 33 NH 2 |
| 18: 0 | 1-octadeylamine | C 18 H 37 NH 2 |
| 20: 0 | 1-eicosylamine | C 20 H 41 NH 2 |
Major fatty amines used in industry are coconut amine , oleyl amine, tallow amine, and soy amine .
application
Important applications of the fatty amines are fabric softeners , flotation agents (for the enrichment of ores) and the corrosion protection of metals. In addition, fatty amines are the basis of many cosmetic products . There they are more likely to be used as fatty amine oxides or ethoxylated fatty amines. One of these fatty amine oxides is dodecyldimethylamine oxide, which is referred to as lauramine oxide according to INCI . This can be found in the ingredients of a conditioner , for example .
Fatty amine salts are cationic emulsifiers which are required to produce oil-in-water emulsions . They are often used in the manufacture of hair care products and act as antistatic agents (which are supposed to make combing the hair easier), as softeners or as water repellants .
By alkylating fatty amines, quaternary ammonium compounds can be obtained and used as a finishing agent for the textile industry . The reaction of fatty amines with chloroacetates gives rise to amphoteric surfactants , of the betaine type .
If fatty amines are oxidized to amine oxides with hydrogen peroxide , a class of nonionic surfactants is formed .
Individual evidence
- ↑ a b c Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke "Amines, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi : 10.1002 / 14356007.a02_001
- ↑ a b c d e entry on fatty amines. In: Römpp Online . Georg Thieme Verlag, accessed on April 21, 2020.
- ↑ J. Barrault, Y. Pouilloux: Synthesis of fatty amines. Selectivity control in the presence of multifunctional catalysts . In: Catalysis Today . 37, No. 2, August 1997, pp. 137-153. doi : 10.1016 / S0920-5861 (97) 00006-0 .
- ^ Entry in Homemade Natural Cosmetics , VCÖ Workshop Chemietage Linz, Marianne Lechner, Borg Grieskirchen, March 2016, accessed on April 20, 2020.