Alkali wash

Prepare the silver oxide by adding a dilute solution of sodium hydroxide to 10 per cent, silver nitrate solution until precipitation is just complete, avoiding an excess of alkali. Wash the precipitate several times by decantation finally, filter at the pump and wash well with water. 

Figure 15 Separation of 1,2/1,4 ketal exposed to acidic or basic conditions. Chromatographic conditions were column 25 cm x 4.6 mm Zorbax C8 (5-pm) column mobile phase 100 mM KH2P04 (pH 6.5) acetonitrile (50 50) flow rate 1.0 ml/min column temperature 35°C detector wavelength 220 nm. (A) Sample exposed to acid-washed flask. (B) Sample exposed to alkali-washed flask.

Alkali-washed material, stabilised with 0.25% of pyrogallol, was distilled at 103°C/4 mbar until slight decomposition began. The heating mantle was then removed and the still-pot temperature had fallen below its maximum value of 135°C when the residue exploded violently [1], The presence of solid alkali [2] or 5% of phenolic inhibitor is recommended, together with low-temperature high-vacuum distillation, to avoid formation of acidic decomposition products, which catalyse rapid exothermic polymerisation. 

Kulski JK, Pryce T. Preparation of mycobacterial DNA from blood culture fluids by simple alkali wash and heat lysis method for PCR detection. J. Clin. Microbiol. 1996 34 1985-1991. 

The presence of sulfur compounds, especially thiophene, in the reagents leads to low yields and a dark-colored product. A good grade of thiophene-free benzene should be used. The benzene may be dried by distillation or by allowing it to stand over calcium chloride. The benzene which is recovered in this preparation may be used in future runs after it has been extracted with alkali, washed, and dried. Small amounts of carbon tetrachloride in the benzene do not interfere, since the quantities of benzene and carbon tetrachloride used are in excess of the relative quantity of the aluminum chloride. 

Phosphates and sulfates correspond to chemical groups which are difficult to photodegrade due to the fact that they adsorb strongly on semiconductor surfaces, particularly titania, even at concentrations as low as 1 mM. In the case of phosphates, the binding with the oxide is so strong that removal with water is inefficient and alkali washing is necessary. Phosphates and sulfates may, however, display singular features as they form reactive species under UV illumination in accordance with eqns (4) and (5) ... 

The alkyl aryl sulfonates are stable to the ordinary acid and alkaline pest control chemicals used by the industry. The materials are stable in either concentrated acid or concentrated alkali washes that might be used for removing residue or skins in processing fruit being effective in such small quantities they afford one of the most practical means for cleaning and processing agricultural crops. 

TBP is a sufficiently powerful extractant for actinides that it may be used in diluted form. Dilution improves the hydrodynamic properties of the solvent, allowing more complete and rapid phase disengagement. Typically concentrations of 20-30 v/o TBP in OK are used in process flowsheets. Although TBP is relatively stable as an extractant, radiolysis does lead to the formation of some acidic phosphate esters, HDBP and H2MBP, which can impair process performance.289 An aqueous alkali wash of the recycled solvent is usually carried out to remove those by products. Radiolytic degradation of the diluent in the presence of nitric acid can result in the formation of hydroxamic acids,290 which can lead to fission product retention by the organic phase. Again the solvent wash is used to prevent the accumulation of such species. A comprehensive account of the industrial utilization of TBP has recently been published.291... 

Mercaptoacetal is sensitive to acid and oxygen. The product should be stored in a dry, alkali-washed bottle under nitrogen in a refrigerator. 

Treat the system with an appropriate acid or alkali wash, depending on the nature of the layer. 

The continuous vapor phase dehydrogenation of piperazines is effectively carried out over a prereduced 80% CuO-20% Cr2Os catalyst at 350°. In this way 2-ethyl-, 2,6-dimethyl-, and 2,3,5,6-tetramethylpiperazines have been converted into the corresponding pyrazines in 79-89% yield.126-128 Pyrazine itself is obtained from piperazine in 18% yield by the use of 5% Pt on alkali-washed firebrick catalyst.129 The catalytic deamination of diethylenetriamine over alumina-based catalysts at temperatures of 300°-400° gives good... 

Such a reaction is controlled by the rate of addition of the acid. The two-phase system is stirred throughout the reaction the heavy product layer is separated and washed thoroughly with water and alkali before distillation (Fig. 3). The alkali treatment is particularly important and serves not just to remove residual acidity but, more importandy, to remove chemically any addition compounds that may have formed. The washwater must be maintained alkaline during this procedure. With the introduction of more than one bromine atom, this alkali wash becomes more critical as there is a greater tendency for addition by-products to form in such reactions. Distillation of material containing residual addition compounds is hazardous, because traces of acid become self-catalytic, causing decomposition of the still contents and much acid gas evolution. Bromination of alkylthiophenes follows a similar pattern. 

Oxidation leads to the formation of di- and tri-nitrocresols, impurities frequently met with in TNT. Nitrocresols are mainly formed during the nitration of toluene to mononitrotoluene (Noelting and Forel [11]). If they have not been removed from mononitrotoluene by washing with alkalis, they undergo either further nitration to trinitrocresol, or oxidation to oxalic acid. Trinitrocresol may be removed from TNT by mild alkali washing (e.g. with a NaHC03 or a sodium sulphite solution). 

Refining involves the purification of triglyceride to remove impurities (phosphatides, polyethylene, chlorophyll, heavy metals, off-odors, color bodies) by a combination of acid/alkali washing, clay/activated silica bleaching, deodorization, and hydrogenation steps. 

Though the purification method of each company has not been disclosed, it is supposed that the gas generated is purified by adsorption method or the use of precision distilling columns after alkali washing and drying. 

The kerosene fraction is essentially a distillation fraction of petroleum. The quantity and quality of the kerosene vary with the type of crude oil some crude oils yield excellent kerosene but others produce kerosene that requires substantial refining. Kerosene is a very stable product, and additives are not required to improve the quality. Apart from the removal of excessive quantities of aromatics, kerosene fractions may need only a lye (alkali) wash if hydrogen sulfide is present. 

Gae maek abaorbent only (1) Alkali Wash eyes with boric acid wash skin with warm sodium carbonate solution Projectiles snd grenades 2 green bands BA gas... 

The dehydrogenation of piperazines to pyrazine was first achieved by Stoehr (32), who heated piperazine (87) or its hydrochloride with zinc dust or, better, zinc dust and lime to give a yield of approximately 10% pyrazine (88). Since that time a number of publications and patents has described the conversion of piperazines to pyrazines by heating at elevated temperatures with various catalysts usually containing copper chromite (464) but also with palladium-charcoal (465) and platinum on alkali-washed firebrick (466), and also with other reagents. Some of these preparations are summarized in Table II.11 (464-475). 

Acid/Alkali wash. To remove mineral scales and metal salt precipitates from the membrane surface, washing with a 1.0% solution of citric acid (or hydrochloric acid) prepared in 25 L of DM water was carried out at a pressure of 10 bar for a 10 min... 

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