Saturated solutions, production

Table 10.13. y-Radiolysis of dGuo (5 x 10 3 mol dm 3) in deaerated and N20-saturated solutions. Products and their G values (unit 10-7 mol J-1 Berger and Cadet 1985)... 

If the product is coloured, dissolve it in 2N sodium hydroxide solution on a water bath. Filter the hot almost saturated solution, and to the hot Bltrate add a... 

For years chemists have been using sodium bisulfite (that is BISULFITE not BISULFATE) to actually crystallize a ketone out of solution in order to separate it. As it so happens, our happy little MD-P2P is a ketone. And when an oil mixture containing it is mixed with a saturated solution of sodium bisulfite (NaHSOs) the MD-P2P crystallizes out as a bisulfite addition product . It can then be easily separated by filtration. Here s how it goes... 

Anhydrous FeF is prepared by the action of Hquid or gaseous hydrogen fluoride on anhydrous FeCl (see Iron compounds). FeF is insoluble in alcohol, ether, and ben2ene, and sparingly soluble in anhydrous HF and water. The pH of a saturated solution in water varies between 3.5 and 4.0. Low pH indicates the presence of residual amounts of HF. The light gray color of the material is attributed to iron oxide or free iron impurities in the product. 

Hexamethylenetetramine. Pure hexamethylenetetramine [100-97-0] (also called hexamine and HMTA) is a colorless, odorless, crystalline sohd of adamantane-like stmcture (141). It sublimes with decomposition at >200° C but does not melt. Its solubiUty in water varies Htde with temperature, and at 25°C it is 46.5% in the saturated solution. It is a weak monobase aqueous solutions are in the pH 8—8.5 range (142). Hexamethylenetetramine is readily prepared by treating aqueous formaldehyde with ammonia followed by evaporation and crystallisation of the soHd product. The reaction is fast and essentially quantitative (142). 

The product stream from the kilns is collected in storage bins. Black ash from the bins is fine-ground in a ball mill and fed to a leacher circuit, which is a system of stirred tanks, where it is dissolved in water and the muds are separated by countercurrent decantation. The solution from the decantation is passed through filter presses the muds are washed, centrifuged, and discarded. The filtered product, a saturated solution containing 12—13 wt % strontium sulfide, is sent to an agitation tank where soda ash is added to cause precipitation of strontium carbonate crystals ... 

A saturated solution of CI2 (0.091 M) at 101 kPa (1 atm) and 25°C is hydrolyzed to HOCl. When CI2 is added to strong bases such as caustic or lime the reaction occurs stepwise. With weak bases such as NaHC03 or CaC03, a significant amount of hypochlorite is not formed as an intermediate product. 

Several features of the hypothetical system in Eigure 2 can be used to illustrate proper selection of crystallizer operating conditions and limitations placed on the operation by system properties. Suppose a saturated solution at temperature is fed to a crystallizer operating at temperature T. Because the feed is saturated, the weight fraction of in the feed is given as shown in Eigure 2. The maximum crystal production rate from such a process depends on the value of and is given by... 

Bofling of 2 under partial reflux (or 7.8 h was followed by distfliation and washing with 30% NaOH, then with a saturated solution of HgCl2 RedistiHatKHi of the product afforded 10 5 g of 3 (15%), bp 19-20 C (760 mm)... 

Tetrakis(triphenylphosphine) platinum [14221-02-4] M 1244.3, m 118". Recrystd by adding hexane to a cold saturated solution in CgHg. It is soluble in C Hg and CHCI3 but insoluble in EtOH and hexane. A less pure product is obtained if crystd by adding hexane to a CHCI3 soln. Stable in air for several hours and completely stable under N2. [7 Am Chem Soc 2323 7958.J... 

Eq. (4e)] is not reduced by metal-ammonia solutions so that the existence of this equilibrium cannot lead to further reduction of the saturated ketonic product only protonation on carbon can result in further reduction (see page 39). 

A solution of 0.46 g of the diazoketone in 100 ml of chloroform is shaken with 22 ml of 48 % hydriodic acid for 1.5 min. After the addition of 400 ml of chloroform, the organic layer is washed successively with a saturated solution of potassium iodide, with a solution of sodium thiosulfate and with water. After drying, evaporation of the solvent yields 0.44 g of a product which is chromatographed over 10 g of alumina (diam. of column 1.0 cm). Elution with benzene (400 ml) and benzene-ether (9 1) (200 ml) gives 0.32 g of 3jS,5) ,19-trihydroxypregnan-20-one 3,19-diacetate (yield 76%) mp 96-99°. 

To a solution of 2.4 g of pregna-1,4,9(11)-triene-21-ol-3,20-dione-[17o ,16a-d] -2 -methylox-azoline 21 -acetate in 24 ml of tetrahydrofuran, 12.8 ml of 0.46N perchloric acid are added at 15°C under stirring. N-bromoacetamide (1.1 g) is then added to the mixture which is kept far from light, and stirred for 4 hours at room temperature. After lowering the temperature to 10°C, a saturated solution of sodium bisulfite is added in order to decolorize the mixture, which is then poured into 120 ml of Ice water. A product separates, which is collected by filtration, washed with water and then dried, thus obtaining 2.81 g of crude 9a-bromo-pregna-... 

The solvent is evaporated and the residue is dissolved in chloroform. This solution is washed with a saturated solution of K2CO3 and dried on K2CO3. The soivent is evaporated and the residue is distilled under high vacuum. The product of the condensation distills near 230°C at 2 mm Hg pressure and the corresponding dihydrochloride melts at 217° to 224°C. 

The residue is the hydrochloride of m-hydroxyphenyl-a-aminoethyl ketone. This is purified by recrystallization from absolute alcohol. It is then dissolved in 200 parts of water and agitated with a further quantity of the palladium catalyst in an atmosphere of hydrogen until saturated. The product thus recovered from the solution is the hydrochloride... 

Then, as described in U.S. Patent 3,158,648, the optical isomers may be resolved as follows. 37 g of racemic a-methYl-3,4-dihYdroxYphenylalanine are slurried at 35°C in 100 cc of 1.0 N hydrochloric acid. The excess solids are filtered leaving a saturated solution containing 34.6 g of racemic amino acid of which about 61% is present as the hydrochloride. The solution Is then seeded at 35°C with 7 g of hydrated L-o -methYl-3,4-dihYdroxYphenYlalanine (6.2 g of anhydrous material). The mixture is then cooled to 20°C in 30 minutes and aged one hour at 20°C. The separated material Is isolated by filtration, washed twice with 10 cc of cold water and dried in vacuo. The yield of product is 14.1 g of L-a-methYl-3,4-di-hydroxyphenylalanine in the form of a sesquihydrate of 100% purity as determined by the rotation of the copper complex. 

Soluble corrosion products may increase corrosion rates in two ways. Firstly, they may increase the conductivity of the electrolyte solution and thereby decrease internal resistance of the corrosion cells. Secondly, they may act hygroscopically to form solutions at humidities at and above that in equilibrium with the saturated solution (Table 2.7). The fogging of nickel in SO2-containing atmospheres, due to the formation of hygroscopic nickel sulphate, exemplifies this type of behaviour. However, whether the corrosion products are soluble or insoluble, protective or non-protective, the... 

Chemical condensation This occurs when soluble corrosion products or atmospheric contaminants are present on the metal surface. When the humidity exceeds that in equilibrium with a saturated solution of the soluble species, a solution, initially saturated, is formed until equilibrium is established with the ambient humidity. The contaminants have already been detailed and of the corrosion products, obviously sulphates, chlorides and carbonates are most important in this context. However, in some cases there is a lack of reliable data on the vapour pressure exerted by saturated solutions of likely corrosion products. The useful data was summarised in Table 2.7. 

One way to establish equilibrium between a slightly soluble solid and its ions in solution is to stir the solid with water to form a saturated solution. As you might expect, the solubility of the solid, s, in moles per liter, is related to the solubility product constant, Ksp. In the case of barium sulfate dissolving in water we have... 

The reaction product, which is a dark reddish-brown liquid, is poured or siphoned (Note 5) into 1.5 1. of water to which 50 cc. of a saturated solution of sodium bisulfite has been added (Note 6). The mixture is distilled with steam (Org. Syn. 2, 80) and the first portion of the distillate is collected separately to remove a small amount of unchanged nitrobenzene. It is necessary to collect about 12 1. of distillate in order to obtain all of the m-bromonitrobenzene. The yellow crystalline solid is filtered with suction and pressed well on the funnel to remove water and traces of nitrobenzene. The yield of crude product varies from 270-340 g. (60-75 Per cent °f the theoretical amount). It melts at 51.5-520 and boils at 117-118 79 mm. This product is satisfactory for most purposes. If a purer material is desired, the crude /w-bromonitrobenzene may be distilled under reduced pressure. The recovery on purification is about 85 per cent. Briihl recorded the b.p. as 1380/18 mm. and the m.p. as 56° for pure wz-bromonitrobenzene.1... 

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