Analyses, lithium concentrates, product

With diphenylhexyllithium 121) (the product of addition of butyl-lithium to 1,1-diphenylethylene) kinetic results are the same as found for fluorenyllithium initiation in the presence of moderate amounts of ether. Even in pure toluene, the rates are first order with respect to initiator concentration and monomer concentration. This simple behaviour is caused by a constant fraction of the initiator forming low molecular weight polymer. If butyllithium is used as initiator, the kinetic behaviour is too complex for analysis. 

To trimethylsilylacetylene (20.4 mmol) dissolved in 80 ml THF at —5°C was added n-butyl lithium (20.4 mmol) followed by the dropwise addition of 3-isobutyl-9,10-dimethoxy-l,3,4,6,7,llb-hexahydro-2H-benzo[a]quinolizidin-2-one dissolved in 30ml THF. The mixture was stirred at -5 °C one hour, slowly warmed to 20 °C, stirred 2 hours, and then quenched with NH4CI solution. THF was removed, the aqueous component extracted 3 times with 100 ml EtOAc, washed with water, brine, and concentrated. The residue was dissolved in 30 ml methyl alcohol containing 5 ml 5 M KOH, heated to 65 °C 30 minutes, then cooled and quenched with NH4CI solution. The solution was concentrated, extracted 3 times with 50 ml EtOAc, washed, dried, and the product isolated in 53.7% yield as a slightly brown solid. Elemental analysis data supplied. 

Once chain initiation is complete, the monomer consumption rate is determined only by the chain propagation step. With the less efficient lithium alkyl initiators in hexane or cyclohexane, rather large amounts of monomer are needed to complete chain initiation. The appearance of a first order decay in monomer concentration, invariably obtained in these experiments, is not a very sensitive indication of the complete absence of initiator. Analysis of trial samples for hydrolysis products of lithium alkyls or spectroscopic determination that the polymer anion concentration has reached a plateau are preferable. A seeding technique is often used [32, 59] where the real initiator is a pre-formed active polymer... 

To a solution of the ketone (20.4 g, 46.9 mmol) in THF (500 mL) at 0 °C was added lithium tri-tert-butoxyaluminohydride l.iAIH(O/-Bu)3l (61.0 mL of a 1.0 M solution in THF, 61.0 mmol). The resulting reaction mixture was stirred for 30 min at 0 °C and then for 30 min at 25 °C. After the reaction was complete, as established by TLC analysis, it was quenched by the addition of saturated ammonium chloride (200 mL) followed by addition of EtOAc (300 mL). The mixture was stirred at 25 °C for 2 h, followed by extraction with EtOAc (3 x 300 mL). The combined extracts were washed with brine, dried over magnesium sulfate, and concentrated to give the crude product, which was purified by flash chromatography (silica gel, 25% EtOAc in hexanes) to afford 19.4 g (95%) of the alcohol as a white sohd. 

ABSTRACT A rapid and precise X-ray fluorescence method has been developed for the multielement analysis of gypsum and gypsum products. Gypsum specimens are calcined at IOOO°C and then fused with sodium tetraborate flux into flat and transparent disks. The choice of a suitable flux system for the specimen preparation is critical because of a rapid decomposition of anhydrite. CaSO,. in lithium ba fluxes at temperatures above 95O C. This decomposition causes not only visible imperfections in the didi surface but also alters considerably the concentrations of the major elements, calcium and sulfur. The procedure used for a fast setup of ten element analysis of gypsum on the Philips PW-1400 spectrometer utilizing synthetic standards and off-line calculated alpha coefficients is presented. Calibrations carried out with chemically analyzed specimens and their mixtures are compared lo those performed with synthetic standards prepared by blending pure chemicals and anhydrite into the flux. 

The analytical measurement of elemental concentrations is important for the analysis of the major and minor constituents of pharmaceutical products. The use of atomic spectroscopy in this regard has been the subject of several reviews (2,3,35,36). Metals are major constituents of several pharmaceuticals such as dialysis solutions, lithium carbonate tablets, antacids, and multivitamin-mineral tablets. For these substances, spectroscopic analysis is an important tool. It is indispensable for the determination of trace-metal impurities in pharmaceutical products and the qualitative and quantitative analysis of metals, essential and toxic, in biological fluids and tissues (37). Beyond this, several drugs which do... 

A 25-mL flame-dried Schlenk tube flushed with argon is charged with ethyl 4-iodobenzoate (2.9 mmol, 773 mg), 1,2-dimethoxyethane (dme) (5 mL) and cooled to -20 °C. Isopropylmagnesium chloride (2.9 mmol, 1.33 mL of a 2.1-M solution in tetrahydrofuran) is then slowly added and the reaction mixture is stirred at -20 °C until GC analysis of reaction aliquots indicates complete exchange. Subsequently, a solution of copper(I) cyanide di(lithium chloride) (2.8 mmol, 2.8 mL of a 1-M solution in tetrahydrofuran) is added and the reaction mixture is stirred for 20 min. A solution of (2,2-diphenylvinyl)trifluoromethanesulfonate (330 mg, 1 mmol) and tris(acetylacetonato)iron (38 mg, 0.1 mmol) in 1,2-dimethoxyethane (3 mL) is added at once at -20 °C and the reaction mixture is stirred at room temperature for 1 h. The reaction is quenched with sat. aq. ammonium chloride and extracted several times with diethyl ether. The combined organic layers are washed with a 2 1 mixture of aq. ammonia and aq. ammonium chloride, and sat. brine, and are dried over magnesium sulfate and concentrated under reduced pressure. Purification by column chromatography (pentane-diethyl ether, 99 1) affords the product as a yellow oil 254 mg (77%). 

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