Acetic acid dissolution

Acetates. Anhydrous iron(II) acetate [3094-87-9J, Ee(C2H202)2, can be prepared by dissolving iron scraps or turnings in anhydrous acetic acid ( 2% acetic anhydride) under an inert atmosphere. It is a colorless compound that can be recrystaUized from water to afford hydrated species. Iron(II) acetate is used in the preparation of dark shades of inks (qv) and dyes and is used as a mordant in dyeing (see Dyes and dye intermediates). An iron acetate salt [2140-52-5] that is a mixture of indefinite proportions of iron(II) and iron(III) can be obtained by concentration of the black Hquors obtained by dissolution of scrap iron in acetic acid. It is used as a catalyst of acetylation and carbonylation reactions. 

Titanium Silicides. The titanium—silicon system includes Ti Si, Ti Si, TiSi, and TiSi (154). Physical properties are summarized in Table 18. Direct synthesis by heating the elements in vacuo or in a protective atmosphere is possible. In the latter case, it is convenient to use titanium hydride instead of titanium metal. Other preparative methods include high temperature electrolysis of molten salt baths containing titanium dioxide and alkalifluorosiUcate (155) reaction of TiCl, SiCl, and H2 at ca 1150°C, using appropriate reactant quantities for both TiSi and TiSi2 (156) and, for Ti Si, reaction between titanium dioxide and calcium siUcide at ca 1200°C, followed by dissolution of excess lime and calcium siUcate in acetic acid. 

These can be prepared as for the benzoates using either acetic anhydride with 3N NaOH or acetyl chloride in pyridine. They are hydrolysed as described for the benzoates. This hydrolysis can also be carried out with aqueous 10% NaOH solution, completion of hydrolysis being indicated by the complete dissolution of the acetate in the aqueous alkaline solution. On steam distillation, acetic acid also distils off but in these cases the phenols (see above) are invariably solids which can be filtered off and recrystallised. 

Acids that are solids can be purified in this way, except that distillation is replaced by repeated crystallisation (preferable from at least two different solvents such as water, alcohol or aqueous alcohol, toluene, toluene/petroleum ether or acetic acid.) Water-insoluble acids can be partially purified by dissolution in N sodium hydroxide solution and precipitation with dilute mineral acid. If the acid is required to be free from sodium ions, then it is better to dissolve the acid in hot N ammonia, heat to ca 80°, adding slightly more than an equal volume of N formic acid and allowing to cool slowly for crystallisation. Any ammonia, formic acid or ammonium formate that adhere to the acid are removed when the acid is dried in a vacuum — they are volatile. The separation and purification of naturally occurring fatty acids, based on distillation, salt solubility and low temperature crystallisation, are described by K.S.Markley (Ed.), Fatty Acids, 2nd Edn, part 3, Chap. 20, Interscience, New York, 1964. 

Cyano-3 -hydroxy-5a-pregnan-20-one A suspension of 5a-pregnane-3, 20-dione (2 g) in ethanol (90 ml) is treated with acetone cyanohydrin (4 ml) and three drops of triethylamine and stirred at room temperature until complete dissolution. After 3 hr, the solution is diluted with 200 ml of water, acidified with acetic acid and the crystalline precipitate is thoroughly washed with water and dried under vacuum to give 2.1 g (97%) of product mp 172-178° (dec). A sample recrystallized from ethyl acetate melts at 176-179° (dec) [a]p 86° (ethyl acetate). 

To the cooled (room temperature) reaction mixture, glacial acetic acid (15 ml) is added dropwise with stirring (formation of pasty solid), followed by 50 ml of ice-cold water (dissolution of the solid). The benzene layer is separated, the aqueous layer is extracted three times with 25-ml portions of benzene, and the combined benzene extracts are washed three times with 25-ml portions of cold water. Benzene is removed by distillation at atmospheric pressure, and excess diethyl carbonate is removed by distillation under aspirator pressure. The residue is distilled under vacuum, affording 2-carbethoxycyclooctanone, bp 85-8770.1 mm, 1.4795-1,4800, about 14 g (94%). 

In addition to the basic corrosion mechanism of attack by acetic acid, it is well established that differential oxygen concentration cells are set up along metals embedded in wood. The gap between a nail and the wood into which it is embedded resembles the ideal crevice or deep, narrow pit. It is expected, therefore, that the cathodic reaction (oxygen reduction) should take place on the exposed head and that metal dissolution should occur on the shank in the wood. 

In a 250-ml., three-necked flask fitted with a mechanical stirrer, a thermometer, and a 25-ml., graduated, pressure-equalizing dropping funnel are placed 7.60 g. (0.050 mole) of phenoxyacetic acid [Acetic acid, phenoxy-] (Note 1), 5.40 g. (0.050 mole) of 1,4-benzoquinone [2,5-Cyclohexadiene-l,4-dioneJ (Note 2), 1 g. (0.006 mole) of silver nitrate [Nitric acid silver(l +) salt] (Note 3), and 125 ml. of water (Note 4). The mixture is then stirred and heated to 60-65° by means of a heating mantle until dissolution is complete. The resulting solution is stirred... 

Reaction (II) could be the neutralization of acetic acid by potassium hydroxide, yielding potassium acetate which can be isolated in the crystalline state. On dissolution in water the K+ cation is only hydrated in solution but does not participate in a protolytic reaction. In this way, the weak base CH3COO is quantitatively introduced into solution in the absence of an equilibrium amount of the conjugate weak acid CH3COOH. Thus... 

Figure 20 Time course of, 3C DDMAS (left panel) and CPMAS (right panel) of [1-13C] Phe22, [3-BC] Ala-label led hCT dissolved in 0.015M acetic acid solution at the concentration of 80 mg/mL pH of the solution was 33. Acquisition was started after 6 h from dissolution by accumulating 1000 scans for DDMAS and 2000 scans for CPMAS experiments (A) 12 h, (B) 26.4 h, and (C) 179.2 h after dissolution. From Ref. 163 with permission.

Szabolcs determined the active principle in preparations based on miconazole and clotrimazole [15]. The two drugs were determined in ointments by extraction with chloroform, evaporation of the solvent, dissolution of the residue in acetic acid, and titration with 0.1 N perchloric acid in the presence of Gentian Violet. 

Dissolve an oligosaccharide or glycan having a reducing end to be modified in 2 1 pyri-dine/glacial acetic acid (vol/vol) with a total reaction volume of 10-100 pi. If the carbohydrate initially is insoluble in the reaction solution, a prior dissolution in a minimal amount of DMSO or water can be done and then an aliquot transferred to the reaction medium. 

Polymer solutions were prepared by dispersing the polymer powder in a saline solution prepared with distilled deionized water. Following complete dispersion in the vortex of the fluid the samples were agitated under mild conditions (< 100 RPM) until the solution was homogeneous. For some solutions the dissolution was so rapid that the agitation step could be eliminated. The polymer viscosities were then measured using a Ubbelohde viscometer. The pH of the polymer solutions was adjusted using dilute acetic acid and sodium hydroxide. Some polymers were supplied as liquids and were subsequently diluted with distilled deionized water to the appropriate concentration. 

Ti/Zr reaction time Acetic acid amount Acetic acid reaction time Solution Concentration Pb dissolution temperature Refluxing... 

Additional Acetic Acid Added Post-Dissolution Water volume... 

The freeze-dried sediments were subjected to both a total dissolution and a selective extraction. The latter, as described in Chester Hughes (1967), is carried out in a hydroxylamine hydrochloride and acetic acid (HA) solution and designed to isolate reactive phases. With the exception of total Se, extracted metals were determined by the method described for porewaters. Total solid Se concentrations were measured by AAS with HG-FIAS (analysis ongoing). 

Sample preparation requires only dissolution of the sample to a suitable concentration in a mixture of water and organic solvent, commonly methanol, isopropanol, or acetonitrile. A trace of formic acid or acetic acid is often added to aid protonation of the analyte molecules in the positive ionization mode. In negative ionization mode ammonia solution or a volatile amine is added to aid deprotonation of the analyte molecules. 

In order to manufacture a diarylide yellow pigment, the diamine, dissolved in hydrochloric acid or sulfuric acid, is bisdiazotized with an aqueous sodium nitrite solution. The resulting diazonium compound is subsequently coupled onto two equivalents of acetoacetarylide. Since a material with a very fine particle size is needed for a fast and complete coupling reaction, the coupling component is prepared by dissolution in an alkaline medium and reprecipitation with an acid, such as acetic acid or hydrochloric acid. Dichlorobenzidine cannot be diazotized stepwise. A lack of sodium nitrite does not produce the monodiazonium compound, but an excess of 3,3 -dichlorodiaminodiphenyl remains. 

Pigment synthesis follows the typical route to azo pigment lakes the aniline derivative or the aniline sulfonic acid is diazotized with sodium nitrite in an acidic medium (hydrochloric acid), followed by coupling on the Naphthol AS derivative, which is initially dissolved in an alkaline solution and then precipitated by adding inorganic or acetic acid. If a Naphthol AS sulfonic acid is used as a coupling component, it must be neutralized with alkali for dissolution and coupled directly. 

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