Nitrate absorption spectrum

Figure 2.4. UV-vis absorption spectrum of 2.4e in water at concentrations of copper(Il)nitrate varying between 0 and 10 mM.

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 . 

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

The ultraviolet absorption spectrum of miconazole nitrate in methanol (0.0104%) shown in Fig. 3 was recorded using a Shimadzu Ultraviolet-visible spectrophotometer 1601 PC. The compound exhibited three maxima at 264, 272, and 280 nm. Clarke reported the following Methanol 264 and 272 nm = 17a), 282 nm [2]. 

The infrared absorption spectrum of miconazole nitrate was obtained in a KBr pellet using a Perkin-Elmer infrared spectrophotometer. The IR spectrum is shown in Fig. 4, where the principal peaks were observed at 3140, 3070, 2995, 2920, 1566, 1525, 1445, 1385, 1310, 1070, and 710 cm-1. Assignments for the major infrared absorption band are provided in Table 2. Clarke reported principal peaks at 1085, 1319, 827, 1302, 1038, and 812 cm-1 (miconazole nitrate, KBr disc) [2]. 

Fig. 4. Infrared absorption spectrum of miconazole nitrate (KBr pellet).

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

Furthermore, the preparation and reactions of 2-methoxythiophene were studied by Sice (70). This compound was obtained by a copper catalysed Williamson synthesis. It was also found that iodothiophene reacted readily with sodium alkoxides, whereas bromothiophene reacted slowly and chlorothiophene did not react at all. Sodium iodide accelerated the reaction of bromothiophene. The ortho, para orienting alkoxy group on carbon atom 2 increased the directive influence of the sulphur atom to the 5 position but competed with it to induce some attack on the 3 position by electrophilic reagents (nitration, acylation). The acylation of 2-methoxythiophene with stannic chloride at low temperatures furnished a mixture of two isomers. The 5-methoxy-2-acetothienone was obtained in higher yield and was identified by its ultraviolet absorption spectrum. 

For our purposes, it is interesting to note that the perovskite ErAlo.9Cro.1O3 emits the continuous spectrum of Cr(III) without the red and green Er(III) bands in spite of the fact that the aqueous solution has e of erbium(III) at 5230 A equal to 3.2 to be compared with a-tenth of e, 1.3 of chromium(III) at 5750 A. The absorption spectrum of the nitrate solution is even more striking in a spectroscope, because the transitions of Er(III) are so much narrower. Quite generally, Cr(III) seems to be very effective to prevent narrow band luminescence of the lanthanides. 

Another transient aminoxyl radical has been generated , and employed in H-abstraction reactivity determinations" . Precursor 1-hydroxybenzotriazole (HBT, Table 2) has been oxidized by cyclic voltammetry (CV) to the corresponding >N—O species, dubbed BTNO (Scheme 9). A redox potential comparable to that of the HPI —PINO oxidation, i.e. E° 1.08 V/NHE, has been obtained in 0.01 M sodium acetate buffered solution at pH 4.7, containing 4% MeCN". Oxidation of HBT by either Pb(OAc)4 in AcOH, or cerium(IV) ammonium nitrate (CAN E° 1.35 V/NHE) in MeCN, has been monitored by spectrophotometry , providing a broad UV-Vis absorption band with A-max at 474 nm and e = 1840 M cm. As in the case of PINO from HPI, the absorption spectrum of aminoxyl radical BTNO is not stable, but decays faster (half-life of 110 s at [HBT] = 0.5 mM) than that of PINO . An EPR spectrum consistent with the structure of BTNO was obtained from equimolar amounts of CAN and HBT in MeCN solution . Finally, laser flash photolysis (LFP) of an Ar-saturated MeCN solution of dicumyl peroxide and HBT at 355 nm gave rise to a species whose absorption spectrum, recorded 1.4 ms after the laser pulse, had the same absorption maximum (ca 474 nm) of the spectrum recorded by conventional spectrophotometry (Scheme 9)59- 54... 

Figure 4.21 shows the absorption spectrum of some simple alkyl nitrates and Tables 4.18, 4.19, and 4.20 give some typical absorption cross sections (Roberts and Fajer, 1989 Turberg et al., 1990 Clemitshaw et al.,... 

Leonard Katzin My first point refers to the question of the nitrate absorption spectrum. If one goes back a decade or more in the literature, there are observations on this peak of a nitrate in nonaqueous solutions of inorganic salts, and I don t believe that the wave length stays fixed. It shifts toward shorter wave lengths—not a great deal, but perceptibly (5). 

The absorption spectrum of nitrocellulose solutions has been examined (Rassow and Aehnelt [135]). It has been established that the capacity to absorb light differs with the origin of the nitrated cellulose. Thus nitrocellulose made from wood pulp gives a slightly different absorption spectrum from that of nitrocotton. 

Reaction of disodium tartrate with silver nitrate at pH S.6 was followed by the change in the absorption spectrum at 216-250 nm. Two complex ions were proposed, Ag(C4H4Oe)- and Ag(C4H406)2, with formation constants log j8i = 2.29 and log / 2 = 4.21 respectively.266... 

Hantzsch opposed the theory of N205 existing in the nitrating mixture HN03 + + H2S04 Due to the importance of the Hantzsch theory in the development of our views on the nature of the nitration process, we shall discuss it in detail. In a number of works Hantzsch [21-23] developed a theory based on Schafer s experiments [24] on the absorption spectrum in ultra-violet light. Schafer s chief observation was, that the spectrum of anhydrous nitric acid in a non-aqueous solvent (hexane, sulphuric acid, etc.) is analogous with the spectra of nitric acid esters,... 

The similarity between the ultra-violet absorption spectrum of nitric acid Mid that of ethyl nitrate in sulphuric acid confirms this conception. 

Ultra-violet absorption spectrum. The first investigations into the ultra-violet absorption spectra of nitric acid, containing certain quantities of water, were carried out by Hartley [55]. He observed that the band at about 302 mp characteristic for the nitrate ion disappears gradually with increase in concentration of nitric acid. 

Kortum and Finckh [167] found the absorption spectrum of the yellow solution was similar to that of the nitrate ion, showing however some difference. 

The reaction between Mo(H20)63+, prepared and purified following the procedure of Bowen and Taube (18), and nitrate was followed spec-trophotometrically under strict anaerobic conditions with nitrate in excess. The absorption spectrum of nitrite in 1.0M HPTS (p-toluene sulfonic acid) exhibits a multicomponent band (vibrational fine structure) between 350 and 400 nm which is attributable to the xBi <— 1A1 electronic transition. Purified Mo(H20)63+ in 1.0M HPTS has a low absorption at 293 nm, indicating the purity of the preparation (18). When Mo(H20)63+ is mixed with nitrate (constant concentration in large excess) and the reaction is allowed to go to completion, the nitrite fine structure appears between 350 and 400, concomitant with an increase in absorbance at 293 nm. The molybdenum species resulting from the oxidation of... 

The triacetate uranyl complex (24) is structurally similar to the trinitrate uranyl complex (6) (three bidentate ligands arranged equa-torially around the uranyl O—U—O axis). It was expected that the visible, near ultraviolet spectrum of the triacetate uranyl complex would be similar to the spectrum of U02(N03)3 as are the spectra of 1102(804)3, 1102(003)3 , and other uranyl complexes which apparently have the same structure (17). The absorption spectrum of uranyl acetate extracted into tri-n-octylamine in xylene from dilute acetic acid is different from the trinitrato uranyl spectrum. This indicates that the triacetate uranyl complex is probably not the species involved. By analogy to the uranyl nitrate system 14), formation of a tetraacetate uranyl complex might be expected. The purpose of this work is to determine the nature of the anionic hexavalent actinide acetate complexes and to identify the species involved in the amine extraction and anion exchange of the hexavalent actinides from acetate systems. 

The electronic absorption spectrum of 69 has been obtained by Shida et al ° and accounted for in MO terms. ESR spectra have also been measured and assigned for nitrated derivatives of 69. ... 

---