Aqueous spectra

Further evidence indicating the presence of methoxyquinone as a product is shown by the neutral aqueous spectra of the eluted compounds... 

Metallic Pu and Am, PuCl3 and Am02 were dissolved in SbF5-HF and in SbF5-HS03F and UV-vis spectra recorded in each solution [29]. Comparison with the known aqueous spectra for Pu(III) and Am(III) indicated the presence in both superacid media of and Pu3+lv) and Am3+lv). Am(IV) in Am02 was reduced to Am(III) in the superacids. 

Gaseous NdBr.3 and Ndls. The spectra of gaseous NdBrs and Ndls appear in Figure 2 together with a comparison of the aqueous spectra, while the observed oscillator strengths and matrix elements appear... 

The development of the theory, taking into account a leading role of the hydrogen bond, is the key problem in the molecular description of aqueous spectra—in particular, of spectra of such important fluids as ice and water [1,2]. Describing water/ice spectra and the method of their calculation represents the objective of this work. 

The n.m.r. spectrum (220 MHz) of N-deuteriated [Pt(en)3] shows small chemical shift differences which were attributed to incomplete conformational averaging. The possibility that these differences may arise from inherent magnetic non-equivalence was excluded on the basis of observed differences in Pt—H coupling constants. Comparison of the aqueous spectrum of... 

Each spectrum is compared with tlie aqueous dilute acid spectrum taken from Sjoblom and Hindman 10) and Waggoner (13). The absorption spectrum of Np(VI) is characterized by a single peak at 1.46jn. It also exhibits the characteristic large absorption in the ultraviolet region, but it does not show any vibrational fine structure. The spectrum of Np(V) is similar to the aqueous spectrum, with the peaks usually smaller in intensity. The major Np(V) peak at 0.983jn, c = 370, is shifted to 1.004/x and reduced in intensity to a molar absorptivity of 104. The Np(IV) spectrum is similar to the aqueous spectrum, showing many sharp peaks. 

Only the IV state of uranium is soluble in saturated KF. Its spectrum, shown in Figure 4, is quite similar to the aqueous spectrum (6). In contrast, the spectrum of the UF2 ion (11) is diflFerent, the sharp peaks no longer being present. 

A study of the chemistry of americium in saturated KF solution has just been started. It is interesting that Am (III) is soluble. The spectrum of Am (III), shown in Figure 5, is surprisingly similar to the normal aqueous spectrum. The major peak at 0.5012jn has a molar absorptivity of 170. Since neither U(III) nor Np(III) is suflBciently soluble for spectral measurements, it will be of interest to try Pu(III). No attempt has been made to oxidize the Am (III) ion, and attempts to reduce Am (III) were unsuccessful. 

Figure Bl.22.8. Sum-frequency generation (SFG) spectra in the C N stretching region from the air/aqueous acetonitrile interfaces of two solutions with different concentrations. The solid curve is the IR transmission spectrum of neat bulk CH CN, provided here for reference. The polar acetonitrile molecules adopt a specific orientation in the air/water interface with a tilt angle that changes with changing concentration, from 40° from the surface nonnal in dilute solutions (molar fractions less than 0.07) to 70° at higher concentrations. This change is manifested here by the shift in the C N stretching frequency seen by SFG [ ]. SFG is one of the very few teclnhques capable of probing liquid/gas, liquid/liquid, and even liquid/solid interfaces.

All the cations of Group I produce a characteristic colour in a flame (lithium, red sodium, yellow potassium, violet rubidium, dark red caesium, blue). The test may be applied quantitatively by atomising an aqueous solution containing Group I cations into a flame and determining the intensities of emission over the visible spectrum with a spectrophotometer Jlame photometry). 

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 aromatic shifts that are induced by 5.1c, 5.If and S.lg on the H-NMR spectrum of SDS, CTAB and Zn(DS)2 have been determined. Zn(DS)2 is used as a model system for Cu(DS)2, which is paramagnetic. The cjkcs and counterion binding for Cu(DS)2 and Zn(DS)2 are similar and it has been demonstrated in Chapter 2 that Zn(II) ions are also capable of coordinating to 5.1, albeit somewhat less efficiently than copper ions. Figure 5.7 shows the results of the shift measurements. For comparison purposes also the data for chalcone (5.4) have been added. This compound has almost no tendency to coordinate to transition-metal ions in aqueous solutions. From Figure 5.7 a number of conclusions can be drawn. (1) The shifts induced by 5.1c on the NMR signals of SDS and CTAB... 

The state of aqueous solutions of nitric acid In strongly acidic solutions water is a weaker base than its behaviour in dilute solutions would predict, for it is almost unprotonated in concentrated nitric acid, and only partially protonated in concentrated sulphuric acid. The addition of water to nitric acid affects the equilibrium leading to the formation of the nitronium and nitrate ions ( 2.2.1). The intensity of the peak in the Raman spectrum associated with the nitronium ion decreases with the progressive addition of water, and the peak is absent from the spectrum of solutions containing more than about 5% of water a similar effect has been observed in the infra-red spectrum. ... 

In equimolar mixtures of nitric acid and water a monohydrate is formed whose Raman spectrum has been observed. There is no evidence for the existence of appreciable concentrations of the nitric acidium ion in aqueous nitric acid. 

In aqueous solutions of sulphuric (< 50%) and perchloric acid (< 45 %) nitrous acid is present predominantly in the molecular form, although some dehydration to dinitrogen trioxide does occur.In solutions contairdng more than 60 % and 65 % of perchloric and sulphuric acid respectively, the stoichiometric concentration of nitrous acid is present entirely as the nitrosonium ion (see the discussion of dinitrogen trioxide 4.1). Evidence for the formation of this ion comes from the occurrence of an absorption band in the Raman spectrum almost identical with the relevant absorption observed in crystalline nitrosonium perchlorate. Under conditions in which molecular nitrous... 

The ultraviolet absorption spectrum of thiazole was first determined in 1955 in ethanolic solution by Leandri et al. (172), then in 1957 by Sheinker et al. (173), and in 1967 by Coltbourne et al. (174). Albert in 1957 gave the spectrum in aqueous solution at pH 5 and in acidic solution (NHCl) (175). Nonhydroxylic solvents were employed (176, 177), and the vapor-phase spectrum was also determined (123). The results summarized in Table 1-15 are homogeneous except for the first data of Leandri (172). Both bands A and B have a red shift of about 3 nm when thiazole is dissolved in hydrocarbon solvents. This red shift of band A increases when the solvent is hydroxylic and, in the case of water, especially when the solution becomes acidic and the extinction coefficient increases simultaneously. 

Hydrolysis of a compound A in dilute aqueous hydrochlonc acid gave (along with methanol) a compound B mp 164—165°C Compound B had the molecular formula CigHig04 it exhibited hydroxyl absorption in its IR spectrum at 3550 cm but had no peaks in the carbonyl region What IS a reasonable structure for compound B" ... 

Treatment of 2 butanone (1 mole) with Br2 (2 moles) in aqueous HBr gave C4HgBr20 The H NMR spectrum of the product was charactenzed by signals at 8 1 9 (doublet three protons) 4 6 (singlet two protons) and 5 2 (quartet one proton) Identify this compound... 

In many applications in mass spectrometry (MS), the sample to be analyzed is present as a solution in a solvent, such as methanol or acetonitrile, or an aqueous one, as with body fluids. The solution may be an effluent from a liquid chromatography (LC) column. In any case, a solution flows into the front end of a mass spectrometer, but before it can provide a mass spectrum, the bulk of the solvent must be removed without losing the sample (solute). If the solvent is not removed, then its vaporization as it enters the ion source would produce a large increase in pressure and stop the spectrometer from working. At the same time that the solvent is removed, the dissolved sample must be retained so that its mass spectrum can be measured. There are several means of effecting this differentiation between carrier solvent and the solute of interest, and thermospray is just one of them. Plasmaspray is a variant of thermospray in which the basic method of solvent removal is the same, but the number of ions obtained is enhanced (see below). 

A sample of the protein, horse heart myoglobin, was dissolved in acidified aqueous acetonitrile (1% formic acid in HjO/CHjCN, 1 1 v/v) at a concentration of 20 pmol/1. This sample was injected into a flow of the same solvent passing at 5 pl/min into the electrospray source to give the mass spectrum of protonated molecular ions [M + nH] shown in (a). The measured ra/z values are given in the table (b), along with the number of protons (charges n) associated with each. The mean relative molecular mass (RMM) is 16,951,09 0.3 Da. Finally, the transformed spectrum, corresponding to the true relative molecular mass, is shown in (c) the observed value is close to that calculated (16,951.4), an error of only 0.002%. 

The checkers performed this step on a smaller scale (ca. f) and noted (proton magnetic resonance spectrum) occasional contamination (up to 10%) by phthalic anhydride. This impurity causes no subsequent difiSculties. Washing of the crude reaction mixture with cold aqueous sodium hydrogen carbonate resulted in serious product loss because of its appreciable solubility in this medium and therefore should be avoided. 

Moreover, solutions of TII3 in MeOH do not show the visible absorption spectrum of I3 and, when shaken with aqueous Na2C03, give a precipitate of TI2O3, i.e. ... 

The Raman spectrum of aqueous mer-cury(I) nitrate has, in addition to lines characteristic of the N03 ion, a strong absorption at 171.7 cm which is not found in the spectra of other metal nitrates and is not active in the infrared it is therefore diagnostic of the Hg-Hg stretching vibration since homonuclear diatomic vibrations are Raman active not infrared active. Similar data have subsequently been produced for a number of other compounds in the solid state and in solution. 

According to Dobbie et the ultraviolet spectrum of cotarnine in dilute aqueous or alcoholic solution is identical with that of cotarnine chloride [(1), Ch instead of OH"], but in nonpolar solvents it is identical with that of hydrocotarnine (10a), 1-ethoxy-hydrocotarnine (10b), and cotarnine pseudocyanide (10c). This is in agreement with Decker s view of the structure of cotarnine and with the conclusions of Hantzsch and Kalb. Measurement of electrical conductivity in-... 

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