Chloride combustion analysis

Treatment of a benzene solution of VI with an excess of nickel chloride in methanol resulted in the precipitation of a yellow powder. This was recrystallized from methanol to give air-stable yellow-orange crystals (60%) with the stoichiometry (VI) NiCl2 -3MeOH (by combustion analysis). When this recrystallized complex was treated with excess aqueous sodium cyanide in the presence of CgDg at room temperature for 10 min VI was regenerated, but now the 3 3P NMR absorptions at 6 -58.1 and -64.0 ppm were in an area ratio of 95 5. Similar treatment of VII with nickel chloride led to a dark oily precipitate which required considerable manipulation to partially purify it. Treatment with sodium cyanide as above led to the regeneration of VII also enriched in the major isomer (85 15). 

In the case of peraksine [RP-5 (27)] it was shown to have the formula C19H22N2O2, a fact not readily derived from combustion analysis since the free base crystallized from alcohol in a hydrated form (27). It has also been observed that this water of solvation could be displaced by chloroform (20). Peraksine has UV-absorption typical of a 2,3-disub-stituted indole and reacted with benzoyl chloride to form an 0-benzoyl derivative. The second oxygen was apparently present as a cyclic ether when it was found that although peraksine did not react with hydrazine derivatives, it was reducible with sodium borohydride to furnish a diol (mp 290°-291° [a]j) - -41° in Py diacetate, mp 103°-105°). This diol readily lost the elements of water upon acid treatment to afford a new ether, deoxyperaksine, 230° change in crystalline form (mp 255°-257°). Because of these properties peraksine was considered to possess a cyclic hemiacetal moiety. 

Analysis of Reagent Purity mp, NMR, combustion analysis. Preparative Methods )V-cyclohexylbenzenesulfonamide can be prepared by addition of benzenesulfonyl chloride to a solution of cyclohexylamine in pyridine and purified by recrystallization from ethanol. TV-Chlorination is accomplished by treating a solution of TV-cyclohexylbenzenesulfonamide in dichloromethane with NaOCl solution at 0°C followed by dropwise addition of glacial acetic acid. Alternatively, a suspension of W cyclohexylbenzenesulfonamide in acetic... 

Preparation. The PS-TsA (eq 1) is prepared in one step from poly styrene-supported benzenesulfonyl chloride (100-200 mesh, 1.5-2.0 mmol/g). Typically, 1.5 mmol of resin is swollen in DMF and then treated with 3.0 mmol of NaNs dissolved in H2O (1.0 mL) and diluted with DMF (7 mL). After 16 h the resin is washed with H2O (5x5 mL), DMF (5x5 mL), and finally with CH2CI2 (3x5 mL) and dried under vacuum at 40 °C. The loading of PS-TsA was determined to be 1.0-1.5 mmol/g by combustion analysis of two different batches. The resin is stored at rt and appears to be stable over an indefinite period of time. FTIR of the resin shows a strong band for the azide functionality at 2130 cm-. ... 

The side-chain chlorine contents of benzyl chloride, benzal chloride, and benzotrichlorides are determined by hydrolysis with methanolic sodium hydroxide followed by titration with silver nitrate. Total chlorine determination, including ring chlorine, is made by standard combustion methods (55). Several procedures for the gas chromatographic analysis of chlorotoluene mixtures have been described (56,57). Proton and nuclear magnetic resonance shifts, characteristic iafrared absorption bands, and principal mass spectral peaks have been summarized including sources of reference spectra (58). Procedures for measuring trace benzyl chloride ia air (59) and ia water (60) have been described. 

The chloride ion is one of the most frequently analysed by IC, e.g. following up combustion of polymers [854,855] similar analyses were reported for the bromide ion [854,855] and nitrite [855]. Analysis of polyester resins for halogens or phosphorous components may be carried out via conversion to halides and phosphates, respectively. 

When HPLC is used as part of the analysis, the mobile phase is typically a mixture of methanol and methyl-tert-butyl ether (i.e., 50 50, v/v), although other HPLC solvents for LC/MS using APCI (e.g., water, tetrahydrofuran) can be used. It is important to note that if combustible nonaqueous solvent systems are used, water or a halogenated solvent such as methylene chloride or chloroform should be added to the mobile phase postcolumn to suppress ignition in the ion source. In addition, the APCI source must be vented outside the laboratory and should not allow air into the ionization chamber. A scan range of m/z 300 to 1000 will include the known carotenoids and their most common esters. 

The four important areas of application of carbon steels are (i) atmospheric corrosion (ii) corrosion in fresh water (iii) corrosion in seawater and (iv) corrosion in soils. The atmospheric corrosion of steel is caused by major environmental factors such as (i) time of wetness as defined by ISO 9223-1992 (ii) sulfur dioxide in the atmosphere due to the combustion of fossil fuels and (iii) chloride carried by the wind from sea. The equations for corrosion rates of carbon steel by multiple regression analysis have been obtained.1... 

Such methods are wet oxidation of pulp followed by estimation of sulfate by precipitation of barium sulfate (Canadian Pulp and Paper Association Standard G28 1970), X-ray fluorescence spectroscopy (Rivington 1988, Kibblewhite et al. 1987), and combustion of pulp followed by analysis of sulfur as sulfur dioxide or as sulfate. The sulfur dioxide evolved is determined by iodometric titration (Canadian Pulp and Paper Association useful method G.7U, March 1959). Sulfate can be determined by titration with barium chloride (Ora 1960), back-titration with sulfuric acid after addition of barium perchlorate (Aldrich 1974), potentiometric titration with lead perchlorate using an ion-selective electrode (Ross and Frant 1969), or ion chromatography (Douek and Ing 1989). 

Problem 2.7 Calculate the percentage composition and then the empirical formula for each of the following compounds (a) Combustion of a 3.02-mg sample of a compound gave 8.86 mg of carbon dioxide and 5.43 mg of water, (b) Combustion of an 8.23-mg sample of a compound gave 9.62 mg of carbon dioxide and 3.94 mg of water. Analysis of a 5.32-mg sample of the same compound by the Carius method gave 13.49 mg of silver chloride. 

Elemental analysis of duplicate samples of econazole nitrate was performed using a Perkin-Elmer 2400 CBN analyser. Approximately 3-mg quantities of material were combusted and measured against an acetanilide standard. The chlorine determination was based on oxygen flask combustion followed by titration against mercuric perchlorate which had been standardized against sodium chloride and chlorobenzoic acid. The oxygen content of the samples was calculated by difference. 

In the inductively coupled argon plasma emission spectrometer method, nickel, iron, and vanadium content of gas oil samples in the range from 0.1 to 100 mg/kg. Thus a 10-g sample of gas oil is charred with sulfuric acid and subsequently combusted to leave the ash residue. The resulting sulfates are then converted to their corresponding chloride salts to ensure complete solubility. A barium internal standard is added to the sample before analysis. In addition, the use of the ICAP method for the analysis of nickel, vanadium, and iron present counteracts the two basic issues arising from metals analysis. The most serious issue is the fact that these metals are partly or totally in the form of volatile, chemically stable porphyrin complexes and extreme conditions are needed to destroy the complexes without losing the metal through volatilization of the complex. The... 

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