Spectra organic solvents effects

Enol imine-enaminone and phenol—quinone tautomerism in (arylazo) naphthols and in analogous Schiff bases were studied by Fabian et al. [92, 93]. In all these molecules there is a favorable N- -H- -O intramolecular hydrogen bond. Depending on the X-H sigma bond (X = N, O), there are two possible tautomers in solution. The solvent effect was calculated on the equilibrium [92], and a combined effect of the solvent and the benzene substituent was studied in [93]. While the FEP/MC simulations provided consistent organic solvent effects in accord with the experimental results [92], the wide spectrum of the solvent-effect calculation methods could predict rather diverse results for several groups of systems in [93]. 

The reaction mixture is diluted with 250 ml of water, the mixture is transferred to a 2 liter flask using methanol as a wash liquid, and the organic solvents are distilled at 20-25 mm using a rotary vacuum evaporator. The product separates as a solid and distillation is continued until most of the residual toluene has been removed. The solid is collected on a 90 cm, medium porosity, fritted glass Buchner funnel and washed well with cold water. After the material has been sucked dry, it is covered with a little cold methanol, the mixture is stirred to break up lumps, and the slurry is kept for 5 min. The vacuum is reapplied, the solid is rinsed with a little methanol followed by ether, and the material is air-dried to give 9.1 g (85%), mp 207-213° after sintering at ca. 198°. Reported mp 212-213°. The crude material contains 1.0-1.5% of unreduced starting material as shown by the UV spectrum. Further purification may be effected by crystallization from methanol. 

The interpretation of these effects as the formation of a proton addition complex was further supported by Plattner et al. (1952) by means of spectroscopic and conductimetric investigations. In these interactions the change of the absorption spectrum is characteristic, since the blue colour of the azulene in organic solvents is changed to a yellow colour in... 

Figure9.8 The absorbance of 1.05 x 10 M pinacyanol chloride at 610.0 min pH 9.59 sodium borate buffer (I = 0.1) at 50 °C vs. dodecanoate concentration. The absorption spectrum of pinacyanol chloride in aqueous solution of anionic soaps changes sharply to one characteristic of its solutions in organic solvents within a small range of soap concentration (X ax 610 nm). This effect is attributed to the formation of micelles, in whose hydrocarbon-like layers or cores the dye is solubilized. The concentration of soap at which this spectral change occurs is taken as the cmc. The use of dyes for the determination of cmc values may lead to micelle formation at a concentration below the true cmc. In practice, the method gives only a rough approximation of the cmc. (Adapted, with some modifications, from Corrin et al., 1946.)...

The compound (Me3tacn)Cr(CN)3 is a yellow microcrystalhne solid that is air-and moisture-stable at room temperature. It is soluble in polar solvents such as water, methanol, acetonitrile, dimethylformamide, and dimethylsulfoxide. It is insoluble in common organic solvents such as ether, dichloromethane, and acetone. Its IR spectrum shows j/cn as a sharp but very weak band at 2132 cm. Its UV-visible absorption spectrum (H2O) shows maxima (e) at 339 (52) and 425 (43) run. At 295 K, the compound exhibits an effective magnetic moment... 

The systems studied were pyrene in SCF CO2, ethylene and CHF3 and naphthalene, dibenzofuran and carbazole in SCF C02 The spectra yield information on both solute/solvent and solute/ solute interactions. A typical spectrum of a dilute pyrene sample is shown in the lower half of Figure 7. Pyrene was chosen for the initial experiments because it has been extremely well investigated in organic liquids and the solvent effect on the spectra is well documented (29). 

Trimethyltin fluoride exists in the crystal as a polymer with a structure close to A. The Mc ,Sn units are planar, and the non-linear Sn-F-Sn bridges are somewhat asymmetric, with Sn-F distances ca. 210 and 220-260 pm, respectively.57 This structure is not easily disrupted, and trimethyltin fluoride, like the the other lower trialkyltin fluorides, is insoluble in unreactive organic solvents. The solid state 119Sn NMR spectrum shows effectively equal coupling to the two adjacent fluorine atoms with (SnF) 1300 Hz.58... 

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