Alkyl amines extraction

For extraction of uranium from sulfate leach Hquors, alkyl phosphoric acids, alkyl phosphates, and secondary and tertiary alkyl amines are used in an inert diluent such as kerosene. The formation of a third phase is suppressed by addition of modifiers such as long-chain alcohols or neutral phosphate esters. Such compounds also increase the solubihty of the amine salt in the diluent and improve phase separation. 

For solvent extraction of pentavalent vanadium as a decavanadate anion, the leach solution is acidified to ca pH 3 by addition of sulfuric acid. Vanadium is extracted in about four countercurrent mixer—settler stages by a 3—5 wt % solution of a tertiary alkyl amine in kerosene. The organic solvent is stripped by a soda-ash or ammonium hydroxide solution, and addition of ammoniacal salts to the rich vanadium strip Hquor yields ammonium metavanadate. A small part of the metavanadate is marketed in that form and some is decomposed at a carefully controlled low temperature to make air-dried or fine granular pentoxide, but most is converted to fused pentoxide by thermal decomposition at ca 450°C, melting at 900°C, then chilling and flaking. 

The secondary aryl amine 24 is far less basic than primary or secondary alkyl amines, and does not form the carbamic acid to any detectable extent in the presence of scC02 [31]. Therefore, 24 is extracted readily from the catalyst-containing IL phase, which can be recycled without noticeable loss of activity and selectivity [13]. In fact, it transpires that the active species is more stable towards oxygen in the IL than in organic solvents. Furthermore, the choice of anion of the IL largely controls the performance of the active cationic species, allowing even the use of an otherwise inactive iridium chloride precursor [ Ir(cod)Cl 2] to form in-situ catalysts... 

Ethoxylated alkyl amines in pesticide formulations were separated using two different columns a cyano-modified silica column to determine the alkyl distribution and an amino-modified column to determine the ethylene oxide distribution [88]. The detection, specific for ethoxylated amine, was performed with a post-column ion-pair extraction system and fluorescence detection. 

The molecular absorption intensity of polar compounds is usually small, but highly sensitive detection can be obtained after pre- or post-column derivatiza-tions. The use of ultraviolet absorption or fluorescence-active counter-ions makes it possible to achieve highly sensitive detection of polar compounds and enhance the capability of ion-pair liquid chromatography. For example, N,N-dimethylprotriptyline has been used as a counter-ion for carboxylic acids12 and picric acid for quaternary amines13 in normal-phase ion-pair partition liquid chromatography. Phenethylammonium, cetylpyridinium, l-phenethyl-2-pyco-linium, and naphthalene-2-sulfonic acid have been used for sulfonic acid and alkyl amines detection.14,15 Ion-pair post-column extraction was applied on-line for fluorescence detection.16... 

The anolyte, containing about 75gdm CD at pFI 2, is fed to a solvent extraction circuit for the separation of Fe—Co and Fe—Ni with a tertiary alkyl amine, dissolved in kerosene. The separation is based on the tendency of the metals to form metal-chloride-amine complexes (Fig. 11.2). At low chloride ion concentration (about 75gdm ), Fe(III) is extracted to the organic solvent, while Co(II) and Ni(II) remain in the aqueous raffinate. If the chloride ion concentration is then increased to about 250 gdm, cobalt is extracted, leaving nickel behind in the raffinate. 

Korenman, I.M., Gurevich, Yu. N., Kulagina, T.G. (1973) Extraction of some n-alkyl amines from aqueous solutions. Zh. Prikl. Khim. (Leningrad) 46(3), 683-684. 

To a limited extent, lanthanoids are separated from each other by tertiary amine extractants and by quaternary ammonium salts with long (Cg and Cio) alkyl groups. Tertiary amines in an organic phase preferentially extract the trivalent actinoids better than the lanthanoids by salting out (dehydrating) the cations from the aqueous phase with high LiCl concentration, e.g., the TRAMEX (tertiary amine extraction) process for Cm isolation . Recent developments in trivalent f-element separations, such as chelating and bifunctional extractants have been reviewed . 

The alkyl amines offer greater selectivity than organophosphorus compounds in many applications, particularly in uranium hydrometallurgy. Amine extraction is typified by the Amex process, which uses a tertiary or branched secondary amine to extract uranium from sulfate leach liquors (11). A similar process based on the use of a primary or straight-chain secondary amine (sometimes modified with an organic-soluble alcohol) has given good results in thorium recovery (12). 

Methoxybicyclo[n.l.O]alkyl)amine (5.0mmol) in EtjO (20mL) was added to a suspension of UAIH4 (0.42 g, 11 mmol) in anhyd EtjO (30 mL), The mixture was refluxed for 12 h (cw-compounds) or 72 h trans-compounds). Then ice-water (50 mL) was slowly added at 20°C. The mixture was extracted with pentane (3 X 30 mL). The solvent was evaporated and the residue was crystallized from pentane or distilled in a Kugelrohr apparatus. 

Ion associate complexes of isopolytungstates with secondary and tertiary alkyl amines play an important role in the technical solvent extraction process (see Section 5.3.)... 

Researchers van der Broeke and coworkers[" created perfluoro-functionalized poly(propyleneimine) dendrimers (23 Fig. 4) and demonstrated their potential as phase-transfer catalysts in supercritical carbon-dioxide-water mixtures and as anionic species extractants. The dendrimers were accessed via reaction of perfluorinated, linear alkyl acid chlorides with the terminal amines. Extraction of perinanganate or dichromate from aqueous to CO2 solution was described as rather low, whereas their use as phase-transfer catalysts in a halogen exchange reaction [benzyl chloride to benzyi bromide (24)] resulted in high rates of conversion. 

Concentrated urine, or a solution of bone ash is made 1 M in HgSO and Pu is extracted by a mixture of highly branched primary alkyl amines. The Pu is then back-extracted with 8 M HCl and counted. 

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