Amines acid extraction

Method 2. Place a 3 0 g. sample of the mixture of amines in a flask, add 6g. (4-5 ml.) of benzenesulphonyl chloride (or 6 g. of p-toluenesulphonyl chloride) and 100 ml. of a 5 per cent, solution of sodium hydroxide. Stopper the flask and shake vigorously until the odour of the acid chloride has disappeared open the flask occasionally to release the pressure developed by the heat of the reaction. AUow the mixture to cool, and dissolve any insoluble material in 60-75 ml. of ether. If a solid insoluble in both the aqueous and ether layer appears at this point (it is probably the sparingly soluble salt of a primary amine, e.g., a long chain compound of the type CjH5(CH2) NHj), add 25 ml. of water and shake if it does not dissolve, filter it off. Separate the ether and aqueous layers. The ether layer will contain the unchanged tertiary amine and the sulphonamide of the secondary amine. Acidify the alkaline aqueous layer with dilute hydrochloric acid, filter off the sulphonamide of the primary amine, and recrystaUise it from dilute alcohol. Extract the ether layer with sufficient 5 per cent, hydrochloric acid to remove all the tertiary amine present. Evaporate the ether to obtain the sulphonamide of the secondary amine recrystaUise it from alcohol or dilute alcohol. FinaUy, render the hydrochloric acid extract alkaline by the addition of dilute sodium hydroxide solution, and isolate the tertiary amine. 

The ease with which amines are extracted into aqueous acid combined with their regeneration on treatment with base makes it a simple matter to separate amines from other plant materials and ni trogen containing natural products were among the earliest organic compounds to be studied Their basic... 

For direct precipitation of vanadium from the salt-roast leach Hquor, acidulation to ca pH 1 without the addition of ammonia salts yields an impure vanadic acid when ammonium salts are added, ammonium polyvanadate precipitates. The impure vanadic acid ordinarily is redissolved in sodium carbonate solution, and ammonium metavanadate precipitates upon addition of ammonium salts. Fusion of the directly precipitated ammonium salts can yield high purity V20 for the chemical industry. Amine solvent extraction is sometimes used to recover 1—3 g/L of residual V20 from the directly precipitated tail Hquors. 

Amines can also be purified via their salts, e.g. hydrochlorides. A solution of the amine in dry toluene, diethyl ether, dichloromethane or chloroform is saturated with dry hydrogen chloride (generated by addition of concentrated sulfuric acid to dry sodium chloride, or to concentrated HCl followed by drying the gas through sulfuric acid, or from a hydrogen chloride cylinder) and the insoluble hydrochloride is filte off and dissolved in water. The solution is made alkaline and the amine is extracted, as above. Hydrochlorides can also be prepared by dissolving the amine in ethanolic HCl and adding diethyl ether or petroleum ether. Where... 

One mole of the chloracetyl xylidide thus prepared and 2.5 to 3 mols diethyl amine are dissolved in 1,000 ml dry benzene. The mixture is refluxed for 4 to 5 hours. The separated diethyl amine hydrochloride is filtered off. The benzene solution is shaken out two times with 3N hydrochloric acid, the first time with 800 ml and the second time with 400 ml acid. To the combined acid extracts is added an approximately 30% solution of sodium hydroxide until the precipitate does not increase. 

The almost dry residue is cooled to 0°C and made strongly alkaline with a 50% potassium hydroxide solution. The amine is extracted into several portions of ether, dried over potassium hydroxide, the solvent removed, and the base fractioned. Reaction of the base with a half-molar quantity of sulfuric acid gives the sulfate. 

The extraction of metals by liquid amines has been widely investigated and depends on the formation of anionic complexes of the metals in aqueous solution. Such applications are illustrated by the use of Amberlite LA.l for extraction of zirconium and hafnium from hydrochloric acid solutions, and the use of liquid amines for extraction of uranium from sulphuric acid solutions.42,43... 

The amines require protonation before they can act as anion exchangers and thus show acid extraction properties in the free base form. For example, a tertiary amine has to react with an inorganic acid in accordance with a reaction of the type ... 

It is interesting to note that some metal ions may exist in solution partly as cationic and partly as anionic species. The uranyl ion is a good example. From sulfate solution it is possible to extract species such as U02(S04)2 with amines. The uranyl cation, on the other hand, can be extracted with acidic extractants such as D2EHPA. 

To obtain an N-substituted amine reflux 0.1M ketone, 17 g aluminum filings or foil, 50 ml ethanol, 40 ml 30% aqueous n-butylamine (or other amine), and 0.5 g of mercuric chloride for 3 hours. Cool and pour on 500 g crushed ice and 200 ml 10% KOH. Extract 3 times with ether and dry, evaporate in vacuum (or wash combined ether layers 2 times with 10% HCI, basify acid extract with 15% NaOH and extract 3 times with ether and dry, evaporate in vacuum) to get the n-butyl-amine (or other amine). 

Metabolites of biogeiuc amines have also been analyzed by GC-ECD. For the simultaneous analysis of 5-hydroxyindole-3-acetic acid (5-HIAA), homovanillic acid (HVA) and m- and p-hydroxyphenylacetic acid (m-, p-HPAA), (metabolites of 5-HT, DA, and m- and p-tyramine acid respectively) in urine, a simple acidic extraction followed by derivatization with PFPA (derivatizes phenols) and hexafluoroisopropanol (deriva-tizes carboxylic acid groups) has been used (Davis et al., 1982 Baker et al., 1987). 

An alternative general process involves coextraction of palladium and platinum, followed by selective stripping (see Fig. 11.12). A novel amino acid extractant, made by the reaction between chloracetic acid and Amberlite LA-2, a secondary amine, is used to extract the two elements from the leach liquor. However, in the given flow sheet, no selective stripping is employed, both elements being stripped by hydrochloric acid. The resulting chloroanions are then separated by using di- -hexylsulfide to extract PdCll. ... 

Cleavage of trichloro-t-butylcarbamates (general procedure) A 1% solution of the trichloro-t-butylcarbamate derivative and 24 mol% of bis(2-thienyl) diteUuride in THF is heated to 60°C under Nj. A 1% aqueous solution of NaBH4 (stabilized with three drops of a 10% NaOH solution) is added dropwise until the red colour of the catalyst disappears. This usually requires 4 or 5 equiv of NaBH4 and is carried out over a period of 30 min. The volatile components are removed in vacuo. The mixture is then poured into HjO and extracted with ether. The amines are isolated by flash chromatography or by acid extraction. 

The (S)-amine 23 was synthesized after 1 day and the enzyme was recovered from the reaction by filtration, then washed and reused. The residual amine was extracted from the MTBE solution with dilute phosphoric acid (pH 2.9-4.4). The aqueous extract was concentrated to give a phosphate salt of the (S)-sec-butylamine with 99.7%. This was followed by a crystallization procedure in ethanol to give 99.8% and 50% yield. 

Moret et al. (67,68) studied all the parameters that influence amine recovery under conditions where a liquid-liquid purification step with an organic solvent follows the acid extraction, prior to derivatization with DBS and RP-HPLC analysis. The optimized methods of sample preparation for different foods, including cheese, meat, and fish, are given. The same research group (69) optimized the extraction conditions for Phe, Put, Cad, His, Tyr, Spe, and Spd. Food samples were first mixed with TCA and centrifuged and then basified and extracted with BuOH/CHCl3 (1 1). The BAs were then derivatized with DNS and separated on a Spherisorb 3S TG column with an ACN-H20 gradient. The method was applied to samples of tuna, salmon, and salami. 

By far the most important use of amine salt extractants is in the recovery of uranium from acidic leach liquors. The basic process was developed at the Oak Ridge National Laboratory in the USA,195 and essentially similar processes are currently in operation throughout the world. Examples of plant practice in the USA,196 Canada,197 Australia,198 South Africa199 200 and South West Africa201 have been described. 

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