Hydroxylamine hydrochloride determination

Dissolve 5 g. of hydroxylamine hydrochloride in 10 ml. of water in a small conical flask and add a solution of 3 g. of sodium hydroxide in 10 ml. of water. Cool the solution in cold or ice water, and add 6 g. (7-6 ml.) of acetone slowly. Cool the flask, shake well, and leave overnight, during which time the oxime may crystallise out. If no crystals appear, cork the flask and shake vigorously when the acetoxime usually separates as colourless crystals. Filter the crystals at the pump, dry rapidly between filter paper (yield 2- 6 g.) and determine the m.p. (59°). Extract the filtrate with two 20 ml. portions of ether, and remove the solvent a further 0 - 5 g. of acetoxime (m.p. 60°) is obtained. Recrystallise from light petroleum, b.p. 40-60° CAUTION inflammable) to obtain the pure acetoxime, m.p. 60°. Acetoxime sublimes when left exposed to the air. 

The purity of a synthetic preparation of methylethyl ketone (C4H8O) can be determined by reacting the ketone with hydroxylamine hydrochloride, liberating HCl (see Table 9.10). In a typical analysis, a 3.00-mL sample was diluted to 50.00 ml and treated with an excess of hydroxylamine hydrochloride. The liberated HCl was titrated with 0.9989 M NaOH, requiring 32.68 ml to reach the end point. Report the percent purity of the sample, given that the density of methylethyl ketone is 0.805 g/mL. 

The assay method involves the reaction of benzaldehyde with hydroxylamine hydrochloride in an alcohoHc solution. Benzaldehyde oxime, water, and hydrochloric acid are the products of the reaction. The hydrochloric acid formed is then titrated with standard caustic solution to determine the benzaldehyde assay. 

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). 

Analytical methods for determining traces of various other impurities, such as chlorides (ASTM D2384), are known to be in use. The presence of acetylenes in rehnery gases, although unlikely, must still be considered. Acetylenes can be determined using a chemical test method, while carbonyls are determined by the classical hydroxylamine hydrochloride reaction (ASTM D1089). 

Urea-formaldehyde resins are generally prepared by condensation in aqueous basic medium. Depending on the intended application, a 50-100% excess of formaldehyde is used. All bases are suitable as catalysts provided they are partially soluble in water. The most commonly used catalysts are the alkali hydroxides. The pH value of the alkaline solution should not exceed 8-9, on account of the possible Cannizzaro reaction of formaldehyde. Since the alkalinity of the solution drops in the course of the reaction, it is necessary either to use a buffer solution or to keep the pH constant by repeated additions of aqueous alkali hydroxide. Under these conditions the reaction time is about 10-20 min at 50-60 C. The course of the condensation can be monitored by titration of the unused formaldehyde with sodium hydrogen sulfite or hydroxylamine hydrochloride. These determinations must, however, be carried out quickly and at as low temperature as possible (10-15 °C), otherwise elimination of formaldehyde from the hydroxymethyl compounds already formed can falsify the analysis. The isolation of the soluble condensation products is not possible without special precautions, on account of the facile back-reaction it can be done by pumping off the water in vacuum below 60 °C imder weakly alkaline conditions, or better by careful freeze-drying. However, the further condensation to crosslinked products is nearly always performed with the original aqueous solution. 

Determine (a) the pH of a 0.0240 m hydroxyl-ammonium chloride (more commonly called hydroxylamine hydrochloride) solution (b) the pH of 0.010 M Na2C03(aq). 

The hydroxylamine hydrochloride used was the crude material prepared as described in Org. Syn. 3, 61. Preliminary experiments showed that this reagent must be present in considerable excess. Equally good results were obtained by using a solution of crude hydroxylamine sulfate which also contained sodium sulfate and ammonium sulfate with a little excess sulfuric acid. The hydroxylamine content was determined in this solution by titration with potassium permanganate solution. When this crude solution is used, the addition of sodium sulfate is not always necessary. 

The mesomeric quinonemethides and 0-quinonemethides described above are somewhat more stable than the simple p-quinonemethides whose properties are already well known even from classical studies. The o-quinonemethides XX and XVII do not add on water even in solution in aqueous organic solvents their solution in dioxane/water is stable for months. They do not add on methanol or higher alcohols and react only slowly with phenols and organic acids. The addition of water is not catalyzed by mild alkalies the red color of the phenoxide ion (XVIII) prevails for weeks in soda solution. Addition of water occurs more rapidly in strongly alkaline solution. The addition of mineral acids and reduction by sodium borohydride are instantaneous. The addition of HC1 is rapid even at pH 4.0, the conditions used for determining the carbonyl content of lignin by the hydroxylamine hydrochloride reaction 13). 

The chelation-extraction method determines chromium metal in hexavalent state. In order to determine total chromium, the metal must be oxidized with KMn04 under boiling and the excess KMn04 is destroyed by hydroxylamine hydrochloride prior to chelation and extraction. 

Procedure Transfer 100 mL of Standard Solution to a 300-mL mercury analysis reaction vessel, add 2 drops of a 1 20 potassium permanganate solution, and mix (the solution should be purple add additional permanganate solution, drop-wise, if necessary). Add 5 mL of 11 A nitric acid, stir, and allow to stand for not less than 15 s. Add 5 mL of 18 A sulfuric acid, stir, and allow to stand for not less than 45 s. Add 5 mL of a 3 200 hydroxylamine hydrochloride solution, stir, and allow to stand until the solution turns light yellow or colorless. Add 5 mL of a 1 10 stannous chloride solution, immediately insert the aerator connected to an air pump, and determine the maximum absorbance of the treated Standard Solution at the mercury resonance line of 253.65 nm, with a suitable atomic absorption spectrophotometer equipped with a mercury hollow-cathode lamp and an absorption cell that permits the flameless detection of mercury. 

Lead Determine as directed under Lead Limit Test, Appendix IIIB, using 25 mL of the following solution Mix 1 g of sample with 3 mL of 1 2 nitric acid and 10 mL of water, and boil until brown fumes evolve. Add 10 mL of water, boil for 2 min, cool, and dilute to 100 mL with water. Use 100 mL of Ammonium Citrate Solution, 1 mL of Potassium Cyanide Solution, 0.5 mL of Hydroxylamine Hydrochloride Solution, and 4 xg of lead (Pb) ion in the control. 

Assay Transfer about 4 g of sample, accurately weighed, into a 250-mL volumetric flask, dissolve in and dilute to volume with water, and mix. Transfer a 25.0-mL portion of this solution into a 400-mL beaker, and add 10 mL of 1 10 hydroxylamine hydrochloride solution, 25 mL of 0.05 M disodium EDTA measured from a buret, 25 mL of ammonia-ammonium chloride buffer TS, and 5 drops of eriochrome black TS. Heat the solution to between 55° and 65°, and titrate from the buret to a blue endpoint. Each milliliter of 0.05 M disodium EDTA is equivalent to 8.450 mg of MnS04H20. Arsenic Determine as directed under Arsenic Limit Test, Appendix IIIB, using a solution of 1 g of sample in 35 mL of water. 

Aldehydes Determine as directed in the Hydroxylatnine/ Tert-Butyl Alcohol Method under Aldehydes and Ketones, Appendix VI, using about 10 g of sample, accurately weighed, and 78.13 as the equivalence factor (e) in the calculation. Allow the samples and the blank to stand at room temperature for 30 min after adding the hydroxylamine hydrochloride solution. 

Procedure Transfer the Sample Solution, prepared as directed in the individual monograph, into a separator, and unless otherwise directed, add 6 mL of Ammonium Citrate Solution and 2 mL of Hydroxylamine Hydrochloride Solution. (Use 10 mL of the citrate solution when determining lead in iron salts.) Add 2 drops of phenol red TS to the separator, and make the solution just alkaline (red in color) by the addition of ammonium hydroxide. Cool the solution, if necessary, under a stream of tap water, then add 2 mL of Potassium Cyanide Solution. Immediately extract the solution with 5-mL portions of Dithizone Extraction Solution, draining each extract into another separator, until the dithizone solution retains its green color. Shake the combined dithizone solutions for 30 s with 20 mL of 1 100 nitric acid discard the chloroform layer add 5.0 mL of Standard Dithizone Solution and 4 mL of Ammonia-Cyanide Solution to the acid solution and shake for 30 s. The purple hue in the chloroform solution of the sample caused by any lead dithizonate present does not exceed that in a control, containing the volume of Diluted Standard Lead Solution equivalent to the amount of lead specified in the monograph, when treated in the same manner as the sample. 

Determination of Total Carbonyl Content of Lignins by Reaction with Hydroxylamine Hydrochloride (Gierer and Soderberg 1959, Gierer and Lenz 1965)... 

Sample Treatments. Blood (1 ml) and fecal samples (1 g dry-matter) were ashed on hot plates by sequential treatment with concentrated nitric acid and 30% hydrogen peroxide. The white residue of each sample was dissolved in 3-5 ml of 6 N HCl, and the final volume was brought up to 25 ml with 6 N HCl. Several 0.1 ml aliquots were transferred to test tubes, and iron concentrations were determined by a colorimetric method using the Batho-reagent (17) which contains hydroxylamine hydrochloride (10%), sodium acetate (1.5 M), and bathophenan-throline disulfonate (0.5 mM). The analytical precision of iron quantification was evaluated by measuring the iron concentrations of 13 replicates of one imenriched fecal sample. The mean of these measurements was 365.7 ug per gram of dry feces, with a relative standard deviation of 2. 8%. 

Hydroxylamine hydrochloride was used as an indicator for the determination of Co(acac)2. The absorbance of the resulting colored solution was measured at 590 nm . Iridium -diketonates were fluorinated oxidatively with BrFs in Freon 113, followed by decomposition in 6M HCl to IrCle and spectrophotometric determination at 488 nm. ... 

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