Mixing solids dissolving

The toluene solution from the previous step was treated with an ethanol solution of NaOEt (0.1 mol in 100 ml) at O C. When about a quarter of the solution had been added a thick precipitate formed and ether (100 ml) was added to maintain a fluid slurry. The remainder of the NaOEt was added and the slurry was stirred overnight. The solid was collected and w ashed with ether. It was then mixed with ether (200 ml) and 2NHC1 (75 ml) and shaken in a separatory funnel until the solid dissolved. The ether layer was washed with 2NHHC1 (2 X 50ml) and water and dried over MgS04. The solution was decolorized with Magnesol and evaporated to give the a-nitro ester as a red oil. 

Determination of calcium. Pipette two 25.0 mL portions of the mixed calcium and magnesium ion solution (not more than 0.01M with respect to either ion) into two separate 250 mL conical flasks and dilute each with about 25 mL of de-ionised water. To the first flask add 4 mL 8 M potassium hydroxide solution (a precipitate of magnesium hydroxide may be noted here), and allow to stand for 3-5 minutes with occasional swirling. Add about 30 mg each of potassium cyanide (Caution poison) and hydroxylammonium chloride and swirl the contents of the flask until the solids dissolve. Add about 50 mg of the HHSNNA indicator mixture and titrate with 0.01 M EDTA until the colour changes from red to blue. Run into the second flask from a burette a volume of EDTA solution equal to that required to reach the end point less 1 mL. Now add 4 mL of the potassium hydroxide solution, mix well and complete the titration as with the first sample record the exact volume of EDTA solution used. Perform a blank titration, replacing the sample with de-ionised water. 

Pb or Ba dioxides 1% finely pulverized Cu 2% an extremely brisant expl. (d) Brisant expls were prepd by mixing solid or liq N.S.N. with PA in all proportions, (e) Gelantinous, dough-like expls can be prepd by dissolving 6p of collodion cotton in 94p of oily N.S.N., preheated to 100°. (f) By incorporating, with warming, 30—40% of AN plus flour into the above mixt (e), a solid mass is obtained which may be pulverized and used in lieu of Dynamites Refs 1) G. Schultz F. Gehr, USP 894707 (1906) 2) C. Distier, E. Blecher C. Lopez,... 

Dissolving a solute in a solvent causes a depression of freezing point, in the same way as mixing solids. 

The hydrogenation of vinylnaphthalene 1 was performed by mixing solid chloro-tris(triphenylphosphine)rhodium catalyst (7.0 mg, 7.6 pmol) with solid 2-vinyl-naphthalene (350 mg, 2.27 mmol, substrate Rh=300 l), both fine powders. The mixture was placed, with a stirring bar, into a 22 mm diameter flat-bottomed glass finer in a 160-mL high-pressure vessel, which was then sealed and warmed to 33 °C in a water bath. The vessel was flushed and pressurized with H2 to 10 bar. This was considered the start of the reaction. Carbon dioxide was then added to a total pressure of 67 bar. After 30 min, the vessel was removed from the water bath and vented. The product mixture was dissolved in CDCI3 and characterized by H NMR spectroscopy. 

To each 9 mg of benzidine, add 10 mL of 0.1 M hydrochloric acid (prepared by slowly adding 1 mL of concentrated acid to 119 mL of cold water). Mix to dissolve. Add 5 mL of 0.2 M potassium permanganate solution (0.3 g of solid potassium permanganate dissolved in 10 mL of water) and 5 mL of 2.0 M sulfuric acid (prepared by carefully adding 1 mL of concentrated acid to 8 mL of cold water). Mix and let stand overnight (at least 10 hours). Decolorize, if necessary, with sodium metabisulfite or ascorbic acid. Neutralize by careful addition of 5 M sodium hydroxide solution (20 g of NaOH dissolved in 100 mL of cold water). Wash the remaining solution into the drain.7... 

So far we have considered solids dissolving in aqueous solutions. Now we will consider the reverse process—the formation of precipitates. When solutions are mixed, various reactions can occur. We have already considered acid-base reactions in some detail. In this section we show how to predict whether a precipitate will form when two solutions are mixed. We will use the ion product, which is defined just like the Ksp expression for a given solid except that initial concentrations are used instead of equilibrium concentrations. For solid CaF2 the expression for the ion product (Q) is written... 

Batch extractors mix a charge of solids and solvent and then let it drain. Immersion extractors cause the solids to pass through a pool of solvent. Percolation extractors carry the solids through a vapor-light chamber where solvent rains down through the solids, dissolving out the oil, similar to the way a coffee percolator works. There are hve major types of percolation extractors basket, rotary, perforated belt, slid-ing-bed, and rectangular loop (151). 

The step-by-step dissolving calculations are done on Figure 10.19 and the dissolving time is 141 s = 2.34 min. This can easily be verified experimentally. We routinely conduct a tabletop solids dissolving experiment in the AIChE Industrial Fluid Mixing Course using a 2" diameter 6BD in a 5" translucent vessel and, at the just suspended speed, the measured dissolving time for 1/8" rock salt varies from 2 to 3 minutes. 

A thermodynamic method, more fitting to this chapter, has been proposed by Nauman et al. They claim a process for the separation of a physically mixed solid polymers by selective dissolution. They rely on the different polymer solubility characteristics. Tables of this property have been reported and are based on regular solution theory and Hildebrand solubility parameters. The core of the Nauman invention is to find suitable solvents to dissolve particular polymers under defined temperature and pressure conditions. A mixture of polymers is first added to one solvent, at a given temperature, in order to dissolve a particular polymer. The remaining polymer mixture is then treated at a higher temperature with the same solvent or with a different solvent. For clarity, two examples are taken from the patent."... 

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