Potassium absorption spectra

In determining the values of Ka use is made of the pronounced shift of the UV-vis absorption spectrum of 2.4 upon coordination to the catalytically active ions as is illustrated in Figure 2.4 ". The occurrence of an isosbestic point can be regarded as an indication that there are only two species in solution that contribute to the absorption spectrum free and coordinated dienophile. The exact method of determination of the equilibrium constants is described extensively in reference 75 and is summarised in the experimental section. Since equilibrium constants and rate constants depend on the ionic strength, from this point onward, all measurements have been performed at constant ionic strength of 2.00 M usir potassium nitrate as background electrolyte . 

Alkaloid A. This forms a chloride, [CjoHjaONjJ+Cl", HjO, isomeric with the chlorides of toxiferine, C-eurarine I and C-curarine III the picrate has m.p. 269° (dec.). The chloride differs from the isomerides named, in potency, colour reactions and ultra-violet absorption spectrum. The chloride in 2N-sulphuric acid gives a carmine-red colour with potassium dichromate. 

Fig. 1.4 Absorption spectrum of a spent luminescence solution of firefly luciferin containing luciferase-oxyluciferin after dialysis in 0.1 M potassium phosphate, pH 7.8. Replotted from the data of Gates and DeLuca, 1975, with permission from Elsevier.

Test 1. Carry out the infrared test according to the general procedure <197 K>. The infrared absorption spectrum of a potassium bromide dispersion of it, previously dried, exhibits maxima only at the same wavelength as that of a similar preparation of USP miconazole RS. 

Transfer a portion of topical powder, equivalent to about 100 mg of miconazole nitrate to a 50 mL beaker, disperse in 40 mL of methanol, and mix for a minimum of 5 min. Allow to settle for 5-10 min, and filter into 100-mL beaker. Evaporate on a steam bath to dryness. Dry the residue at 105 °C for 10 minutes the infrared absorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Miconazole Nitrate RS. 

The spectrum exhibits maxima at 281 and 223 nm with molar absorptivities of 4,768 and 14,400, respectively. When aqueous potassium hydroxide is added to the methanolic solution of dobutamine hydrochloride the maxima at 281 and 223 shift to 293 (e=6,100) and 240 nm, respectively. These shifts are reversible by addition of hydrochloric acid. When the absorption spectrum of the drug is recorded in water rather than methanol, slight shifts in peak positions and intensities are observed ... 

Figure 2. Infrared Absorption Spectrum of Hydralazine Base, Potassium Bromide Pellet and Mull.

The 2,5-dihydro-l,2,3,5-thiatriazole 1-oxides react with phosphorous pentachloride (or penta-bromide) in chloroform to give yellow 2/f-l,2,3,5-thiatriazol-l-ium salts (16). The salts are very sensitive to moisture and hydrolyze back to the starting material. The structure is determined by x-ray crystallography. The yellow color is due to the extended delocalization of the cation which gives rise to a broad band system in the 300 nm to 450 nm range in the absorption spectrum. Upon treatment with sodium or potassium in 1,2-dimethoxyethane a 2,5-dihydro-l,2,3,5-thiatriazol-5-yl... 

The infi red absorption spectrum of benzoic acid was obtained in a potassium bromide disc (using approximately 2 mg of benzoic acid dispersed in 200 mg KBr), and recorded on a Jasco 5300 FTIR spectrophotometer. The spectrum thusly obtained is shown in Figure 6, and the assignment of the characteristic bands is given in Table 3. 

Figure 6. Absorption spectrum of potassium amide in liquid ammonia (

Atkinson and Cossey148 reported that the reduction of 2-methyl-5,6-diphenyltriazinium iodide (141) with potassium borohydride in methanol led to a tetrahydro-2-methyl-5,6-diphenyl-l,2,4-triazine. The ultraviolet absorption spectrum of this tetrahydro-l,2,4-triazine showed a maximum at 297 mfi (loge = 4.06). A similar reduction of l-methyl-3,5,6-triphenyl-l,2,4-triazinium iodide (142) gave a dihydro-1,2,4-triazine, the ultraviolet spectrum of which had maxima at 273 mft (loge = 4.46) and 410-420 m/x (loge = 3.62). No assignment of... 

Fig. 11. Absorption spectrum of the 3 1 ferropyrimine complex at pH 4.0 in potassium phthalate buffer. 0.05m See Reference (119).

An interesting case of selective oxidation in solution is given hy Jones,2 who has studied the absorption spectrum of a solution of uranous bromide in a mixture of water and methyl alcohol. Addition of potassium perchlorate effects an alteration in the absorption bands m such a manner as to show that the portion of the uranous salt combined with the methyl alcohol has undergone no change, whilst that united with the water has become oxidised. 

A. The infrared absorption spectrum of a potassium bromide dispersion of the sample exhibits relative maxima at the... 

Identification The infrared absorption spectrum of a melted sample on a potassium bromide plate exhibits relative maxima at the same wavelengths as those of a typical spectrum as shown in the section on Infrared Spectra, using the same test conditions as specified therein. 

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