Dilute solutions extraction from

Basic Component. The filtrate from (a), or the HCl extract from b), now contains the basic component in the form of its hydrochloride. Add 30% aqueous NaOH solution until alkaline to litmus. Cool, and scratch the sides of the vessel with a glass rod a white precipitate indicates a solid amine, e.g, p-toluidine or a naphthylamine. Dilute, filter off, wash well with water (recrystallise if necessary), dry and identify. 

Suspend in a round-bottomed flask 1 g. of the substance in 75-80 ml. of boihng water to which about 0 -5 g. of sodium carbonate crystals have been added, and introduce slowly 4 g. of finely-powdered potassium permanganate. Heat under reflux until the purple colour of the permanganate has disappeared (1-4 hours). Allow the mixture to cool and carefully acidify with dilute sulphuric acid. Heat the mixture under reflux for a further 30 minutes and then cool. Remove any excess of manganese dioxide by the addition of a little sodium bisulphite. Filter the precipitated acid and recrystallise it from a suitable solvent (e.g., benzene, alcohol, dilute alcohol or water). If the acid does not separate from the solution, extract it with ether, benzene or carbon tetrachloride. 

Note on the laboratory preparation of monoethylaniline. Although the laboratory preparation of monomethyl- or monoethyl-aniline is hardly worth whUe, the following experimental details may be useful to those who wish to prepare pure monoethylaniline directly from amline. In a flask, fitted with a double surface reflux condenser, place 50 g. (49 ml.) of aniline and 65 g. of ethyl bromide, and boU gently for 2 hours or until the mixture has almost entirely sohdified. Dissolve it in water and boil off the small quantity of unreacted ethyl bromide. Render the mixture alkaUne with concentrated sodium hydroxide solution, extract the precipitated bases with three 50 ml. portions of ether, and distil off the ether. The residual oil contains anihne, mono- and di-ethylaniline. Dissolve it in excess of dilute hydrochloric acid (say, 100 ml. of concentrated acid and 400 ml. of water), cool in ice, and add with stirring a solution of 37 g. of sodium nitrite in 100 ml. of water do not allow the temperature to rise above 10°. Tnis leads to the formation of a solution of phenyl diazonium chloride, of N-nitrosoethylaniline and of p-nitrosodiethylaniline. The nitrosoethylaniline separates as a dark coloured oil. Extract the oil with ether, distil off the ether, and reduce the nitrosoamine with tin and hydrochloric acid (see above). The yield of ethylaniline is 20 g. 

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. 

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

Ck)ol the alkaline solution resulting from the distillation of the volatile neutral compounds, make it acid to litmus with dilute sulphuric acid, and add an excess of solid sodium bicarbonate. Extract this bicarbonate solution with two 20 ml. portions of ether remove the ether from the combined ether extracts and identify the residual phenol (or enol). Then acidify the bicarbonate solution cautiously with dilute sulphiu-ic acid if an acidic compound separates, remove it by two extractions with 20 ml. portions of ether if the acidified solution remains clear, distil and collect any water-soluble, volatile acid in the distillate. Characterise the acid as under 2. 

Description of Method. Quinine is an alkaloid used in treating malaria (it also is found in tonic water). It is a strongly fluorescent compound in dilute solutions of H2SO4 (f = 0.55). The excitation spectrum of quinine shows two absorption bands at 250 nm and 350 nm, and the emission spectrum shows a single emission band at 450 nm. Quinine is rapidly excreted from the body in urine and is easily determined by fluorescence following its extraction from the urine sample. 

The development of selective extractants for copper has made extraction from dilute solutions (1—5 kg/m ) economically feasible. Transfer of the copper by stripping to a more concentrated sulfuric acid solution, ie, 30—40 kg/m for Cu " and 150—170 kg/m for H2SO4, from which the copper is recovered by electrowinning. The simplified reaction,... 

Aluminum nitrate nonahydrate is prepared by dissolving aluminum or aluminum hydroxide in dilute nitric acid, and crystaUi2ing the product from the resulting aqueous solution. It is made commercially from aluminous materials such as bauxite. Iron compounds may be extracted from the solution with naphthenic acids (21) before hydrate precipitation. In the laboratory it is prepared from aluminum sulfate and barium nitrate. 

The extraction of metal ions depends on the chelating ability of 8-hydroxyquinoline. Modification of the stmcture can improve its properties, eg, higher solubility in organic solvents (91). The extraction of nickel, cobalt, copper, and zinc from acid sulfates has been accompHshed using 8-hydroxyquinohne in an immiscible solvent (92). In the presence of oximes, halo-substituted 8-hydroxyquinolines have been used to recover copper and zinc from aqueous solutions (93). Dilute solutions of heavy metals such as mercury, ca dmium, copper, lead, and zinc can be purified using quinoline-8-carboxyhc acid adsorbed on various substrates (94). 

These species are also unusual iu that they are extremely hydrophobic anions which form very strong conjugate acids. This unique combination of features leads to a number of potential uses such as the extraction of organic compounds from extremely dilute solutions and the isolation of metal cations, including the quantitative separation of radionucUdes, eg, Cs (192). 

Sodium cyanide [143-33-9] NaCN, is a white cubic crystalline soHd commonly called white cyanide. It was first prepared in 1834 by heating Pmssian blue, a mixture of cyanogen compounds of iron, and sodium carbonate and extracting sodium cyanide from the cooled mixture using alcohol. Sodium cyanide remained a laboratory curiosity until 1887, when a process was patented for the extraction of gold and silver from ores by means of a dilute solution of cyanide (see Metallurgy, extractive). A mixture of sodium and potassium cyanides, produced by Edenmeyer s improvement of the Rodgers process, was marketed in 1890. 

Alkannin occurs in the roots of the plant as the alkah-sensitive ester of angelic acid (62). It may be extracted from the roots by using boiling light petroleum ether. Treatment of this extract with dilute sodium hydroxide gives a blue solution from which the dye is precipitated by the addition of acid. The cmde product is purified by vacuum sublimation (63). Its stmcture (11) is a hydroxylated naphthoquinone with a long, unsaturated side chain (64,65) it has the (3)-configuration. 

Recovery. The principal purpose of recovery is to remove nonproteinaceous material from the enzyme preparation. Enzyme yields vary, sometimes exceeding 75%. Most industrial enzymes are secreted by a microorganism, and the first recovery step is often the removal of whole cells and other particulate matter (19) by centrifugation (20) or filtration (21). In the case of ceU-bound enzymes, the harvested cells can be used as is or dismpted by physical (eg, bead mills, high pressure homogenizer) and/or chemical (eg, solvent, detergent, lysozyme [9001 -63-2] or other lytic enzyme) techniques (22). Enzymes can be extracted from dismpted microbial cells, and ground animal (trypsin) or plant (papain) material by dilute salt solutions or aqueous two-phase systems (23). 

Selectivity. The relative separation, or selectivity, Ot of a solvent is the ratio of two components in the extraction-solvent phase divided by the ratio of the same components in the feed-solvent phase. The separation power of a hquid-liquid system is governed by the deviation of Ot from unity, analogous to relative volatility in distillation. A relative separation Ot of 1.0 gives no separation of the components between the two liquid phases. Dilute solute concentrations generally give the highest relative separation factors. 

The heptamethylene glycol was separated by continuous ether extraction from the alkaline reduction solution after the latter had been diluted and distilled to remove the alcohol. The nonamethylene glycol was separated from the alkaline liquor by decantation (as above) and distilled. All the others were crystallized from benzene (without alcohol). Equally successful results have also been obtained with larger runs (e.g., 0.5 mole of ester),... 

Acetylene is passed for 1 hr through a mixture consisting of 0.5 g (72 mg-atoms) of lithium in 100 ml of ethylene-diamine. A solution prepared from 1 g (3.5 mmoles) of rac-3-methoxy-18-methylestra-l,3,5(10)-trien-I7-one and 30 ml of tetrahydrofuran is then added at room temperature with stirring over a period of 30 min. After an additional 2 hr during which time acetylene is passed through the solution the mixture is neutralized with 5 g of ammonium chloride, diluted with 50 ml water, and extracted with ether. The ether extracts are washed successively with 10% sulfuric acid, saturated sodium hydrogen carbonate and water. The extract is dried over sodium sulfate and concentrated to yield a solid crystalline material, which on recrystallization from methanol affords 0.95 g (87%) of rac-3-methoxy-18-methyl-17a-ethynyl-estra-l,3,5(10)-trien-17jB-ol as colorless needles mp 161°. 

After cooling, the solution was diluted with 1.5 liters of water and subjected to three extractions with ether. The amine was extracted from the ethereal solution with 2 N HCI and liberated therefrom by the addition of solid NaOH (while cooling). The alkaline solution was extracted with ether and the ethereal solution was dried with soiid NaOH. Distii-lation resulted in 10.6 grams (70% of the theory) of 1-aminoadamantane which, after sublimation, melted at 180° to 192°C (seal capillary). It is converted to the hydrochloride. 

The mixture is taken up with water and the base is extracted from the toluene with dilute hydrochloric acid. The hydrochloric solution is rendered alkaline with caustic soda, the base is separated with ether, dried, and after distillation of the ether fractionated in vacuo, BP at 0.05 mm Hg, 150° to 153°C. The basic ether is then dissolved in dry ether, and ether saturated with dry hydrogen chloride is added dropwise with stirring. An excess of hydrogen chloride must be avoided as it may produce decomposition to the corresponding diphenyl ethylene. The ether-moist hydrochloride is preferably dried at once in vacuo and subsequently reprecipitated from acetone-ether and then again dried in vacuo over phosphorus pentoxide. Hydrochloride, MP 12B°C. 

The reaction mixture was then dissolved in methylene chloride, the amine was removed by shaking with dilute hydrochloric acid, the reaction product was extracted from the organic phase by means of dilute sodium hydroxide solution and the alkaline solution was acidified with acetic acid to a pH value of 6. The 1 -hvdroxv-4-methyl-6-cvclohexvl-2-pyridone precipitated in crystalline form. It was filtered off with suction, washed with water and dried. The yield was 1.05 g (49% of theory) melting point 143°C. 

In about 250 cc of liquid ammonia (cooled with dry ice and acetone) are dissolved about 7.5 g of potassium and into the solution acetylene is passed until the blue color has disappeared (about 3 hours). Then slowly a solution or suspension of 3 g of estrone in 150 cc of benzene and 50 cc of ether is added. The freezing mixture is removed, the whole allowed to stand for about 2 hours and the solution further stirred overnight. Thereupon the reaction solution is treated with ice and water, acidified with sulfuric acid to an acid reaction to Congo red and the solution extracted five times with ether. The combined ether extracts are washed twice with water, once with 5% sodium carbonate solution and again with water until the washing water is neutral. Then the ether is evaporated, the residue dissolved in a little methanol and diluted with water. The separated product is recrystallized from aqueous methanol. The yield amounts to 2.77 g. The 17-ethiny I-estradiol-3,17 thus obtained melts at 142°C to 144°C . 

The mixture is then slowly heated to the boiling point of toluene and kept boiling for one hour under reflux. After the mixture has been allowed to cool the sodium chloride which precipitates is separated by extraction with water. The solution of toluene is then extracted with dilute hydrochloric acid. From the hydrochloric acid extract the basic substance is separated in the form of an oil by means of caustic soda solution and is introduced into ether. The ethereal solution Is dried with the aid of potassium carbonate and then distilled. 

Prepare a blank solution by carrying through all the sequences of the separation procedures using a hydrochloric acid solution to which no alloy has been added, and then measure the absorption given by this blank solution, by a series of standard solutions containing from 1 to 10 /rg Pb mL 1 prepared by suitable dilution of the lead caprate stock solution (see Note), and finally of the extract prepared from the sample of alloy. Plot the calibration curve and determine the lead content of the alloy. 

To a solution of 1 equiv of( + )-(R)-methyl 4-tolyl sulfoxide (1) inTHF is added a solution of 1 equiv of LDA at 0°C and, after cooling to —78 C, a solution of 1 equiv of an appropriate imine 2. Addition is usually complete within 10 min. The reaction is quenched with dilute HCI, extracted with CH,C12 and the extracts are dried and evaporated. The products are purifed by Hash chromatography (silica gel). The main diastcreomer can be isolated by crystallization from cyclohexane. No further preparative details are available. 

Cobalt at a dilution of 1 gg per liter was completely recovered and successfully determined by use of an ion-exchange membrane. Similar results were obtained with other heavy metals. Potassium in amounts from 5 to 150 /xg inJ75 ml.was extracted from aqueous solutions and from mica surfaces, on which it is present as an exchangeable ion.26... 

M HNO3) and from 3 M HNO3 using dilute solutions of DHDECMP, HHDECMP, 0(j)D[IB]CMP0 in o-xylene showed that the increase in D/ in the series phosphone-phosphinate-phosphine oxide was due primarily to an increase in the enthalpy of extraction. 

The cyclic oligomers are only slightly soluble in water and dilute solutions of caprolactam. They tend to separate out from die extracted waste during die process of concentration and chemical purification of die caprolactam. The cyclic oligomers tend to form on the walls of the equipment used in die process equipment. 6-Aminocaproic acid or sodium 6-aminocaproate may also be found in die oligomeric waste, especially if sodium hydroxide is used to initiate die caprolactam polymerization. 

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