Water soluble impurities

The methyl ethyl ketazine forms an immiscible upper organic layer easily removed by decantation. The lower, aqueous phase, containing acetamide and sodium phosphate, is concentrated to remove water formed in the reaction and is then recycled to the reactor after a purge of water-soluble impurities. Organic by-products are separated from the ketazine layer by distillation. The purified ketazine is then hydrolyzed under pressure (0.2—1.5 MPa (2—15 atm)) to give aqueous hydrazine and methyl ethyl ketone overhead, which is recycled (122). The aqueous hydrazine is concentrated in a final distillation column. 

Example 10.2 An organic product with a flowrate of lOOOkg-h-1 contains a water-soluble impurity with a concentration of 6% wt. A laboratory test indicates that if the product is extracted with an equal mass of water, then 90% of the impurity is extracted. Assume that water and the organic product are immiscible. 

Water soluble impurities and their effect can be easily included in equation (1-4), through which they are going to directly affect the particle nucleation rate, f(t). If one assumes a first order reaction of an active radical with a water soluble impurity (WSI) to give a stable non-reactive intermediate, then one simply has to add another term in the denominator of equation (1-4), of the form kwsr[WSI](t)-kv, and to account for the concentration of WSI with a differential equation as follows ... 

Since the above treatment would insert an additional parameter in the system (i.e. an additional piece of uncertainty), that of kwsi> and since water soluble impurities usually manifest themselves as an induction time for the polymerization reaction, the empirical treatment of (32) might be more than satisfactory. 

A toluene water wash process is shown in Figure 10-12. This process is used to clean water-soluble impurities from contaminated toluene. The separation is achieved with a Podbielniak centrifuge, or Pod, because of a difference in densities. The light phase (contaminated toluene) is fed to the periphery of the centrifuge and travels to the center. The heavy phase (water) is fed to the center and travels countercurrent to the toluene to the periphery of the centrifuge. Both phases are mixed within the centrifuge and separated countercurrently. The extraction is conducted at 190°F. 

The emulsion is separated in the centrifugal contactor (POD), which produces a stream containing water-soluble impurities and a stream of washed solvent. 

Wash cartridge with 30 column volumes deionized distilled water to remove water-soluble impurities (sugars, acids). 

Perfetti et al. (131) described a method for the determination of ethoxyquin in milk. Milk solids were precipitated by adding acetonitrile, and the water-acetonitrile supernatant was washed with hexane to remove fat. The addition of NaCl caused the water-acetonitrile solution to separate into an aqueous phase and an acetonitrile phase, thus separating ethoxyquin from most water-soluble impurities. A large volume of water was then added to the acetonitrile layer, and ethoxyquin was partitioned into hexane and removed at reduced pressure. The residue was dissolved in the mobile phase and analyzed on a 250-mm X 4.6-mm-ID. Ultrasphere ODS column using fluorescence detection with excitation of 230 nm, and emission of 418 nm, respectively. A mixture of water and acetonitrile with a diethylamine-acetic acid buffer was the mobile phase. Recoveries from milk samples fortified at 1, 5, and 10 ng/g averaged 78%, with a coefficient of variation of 5.0%. Low concentrations (less than 1 ng/g) of apparent ethoxyquin were detected in commercial milk samples analyzed by this method. 

When a sucrose- or other simple carbohydrate-based solution is mixed with yeast and oxygen in a fermenter, carbon dioxide vapour and alcohol are produced. The carbon dioxide can then be passed through a separator to remove any trace cany-over of foam. Once the foam has been removed the carbon dioxide is compressed. It is then scrubbed with water in a packed tower, removing water-soluble impurities such as alcohol, ketones and other aroma chemicals produced during fermentation. 

Various procedures for the purification of specific amine-boranes have been reported.12 Ethylenediamine-bisborane can be purified conveniently by aqueous extraction to remove water-soluble impurities. The crude product obtained from the tetrahydrofuran solution is ground to a fine powder in a mortar and added in small portions, with stirring, to about 75 ml. of water which has been cooled in an ice-water bath. Foaming may occur during this treatment. The white crystalline solid which does not dissolve is collected by filtration through a coarse-fritted-glass funnel and washed several times with small portions of cold water (about 5°C.). The final wash filtrate should be neutral toward pH paper. The product is dried by... 

The emulsion enters the desalter vessel where a high-voltage electrostatic field is applied. The electrostatic field causes the dispersed water droplets to coalesce, agglomerate, and settle to the lower portion of the vessel. The various contaminants from the crude oil concentrate in the water phase. The salts, minerals, and other water-soluble impurities are discharged from the settler to the effluent system. Clean, desalted hydrocarbon product flows from the top of the settler and is ready for the next processing step. 

The lead hydroxide is prepared by adding 1.5 1. of a 2 N solution of sodium hydroxide (3 moles) through a dropping funnel to a continuously stirred solution of 569 g. (1.5 moles) of lead acetate, (CH3C02)2l)b-3H20, in 1.35 1. of water. The precipitate is collected on a 13-cm. Buchner funnel and washed well with water in order to remove water-soluble impurities. The paste of lead hydroxide is transferred to the solution that is to be freed of chloride ions. 

In this way, constituents of the first molasses produced by solvent washing of raw sugar crystals can be separated by a second solvent. Preferably it is one that removes the less water-soluble impurities—oils, fats, waxes, aconitic acid, chlorophyl, etc.—from the sucrose and invert sugar. Hydrocarbons and chlorinated hydrocarbons, ethers, higher alcohols, and ketones have disadvantages as a solvent—e.g., they often form relatively stable emulsions. 

In all cases, the latexes were dialyzed to remove water-soluble impurities and salts. This process also removed part of the soap. The dialyzed latexes were then analyzed and reformulated to the desired level of charge with the appropriate emulsifier. 

Reslurrying can sometimes be avoided by simply changing the work-up or crystallization procedures. If reslurrying removes water-soluble impurities, including an aqueous wash during the work-up may eliminate the need to reslurry the product. Alternatively, the product may be crystallized from solvents that dissolve impurities that would otherwise be removed by reslurrying. 

Further improvement of throughput in LC-MS analysis may be achieved by step-gradient elution. This elution format is essentially an on-line solid-phase extraction (SPE) process, where the samples are loaded onto the column, washed with aqueous mobile phase to remove water soluble impurities, and compounds are eluted with a mobile phase of high organic content. The technique combines the simplicity of FIA with the benefit of the removal of impurities and buffer components before mass spectrometry detection. In this case, selectivity is achieved by mass spectrometry alone without chromatographic separation. The technique has been used for compound purity assessment and quantitation. An on-line back-flush SPE-MS technique has been used by Marshall for quality assessment of the combinatorial libraries [112]. This back-flush elution procedure provides a very effective in-line removal method... 

When adsorption is finished, one washes carbon with 15 liters of distilled water until one cannot detect any more, in the filtrate, of water soluble impurities, and then one subjects this coal to an elution with 50 liters of methanol added with 10% of concentrated ammonia. The eluate is concentrated to 1 liter under 20 torr at 30° and the acid carboxylic, which crystallized at the end of twenty-four hours, is dried under 1 torr at 80°. The recovery is 45.3 grams is 91% of the theoretical quantity. 

Lac incmstations deposited by the insects on trees are separated from the twigs by scraping. Lac, thus gathered is known as stick lac. It contains lac resin together with woody materials, sand, dust and other water-soluble impurities. This is subjected to various refining processes. The various refined forms of sticklac are seedlac, shellac, buttonlac, garnet lac, bleached lac, and decolorized lac. 

Theory. It is assumed that the absorption of water by rubbers is due to the presence of water soluble Impurities. 

The diffusion of water in natural rubber is complicated by the presence of water soluble impurities in the rubber. 

Now, working backward, the solubility of free base 2 was examined. This compound had a solubihty of approximately 37 mg/mL in the 20% water/1-butanol solvent system at room temperature. Any more water added to this solvent system formed a separate phase, rendering this solvent system an attractive option for the extractive removal of water-soluble impurities. Moreover, in an effort to minimize the number of solvents used in the process. Step 1C reaction was also attempted in 1-butanol and was shown to be extremely efficient. 

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