Ethanol, proton magnetic resonance

Towner RA, Reinke LA, Janzen EG, et al. 1991. Enhancement of carbon tetrachloride-induced liver injury by a single dose of ethanol proton magnetic resonance imaging (MRI) studies In vivo. Acta Biochem Biophys 1096 222- 230. 

The submitters obtained 59.6-64.1 g. (65-70%) of product melting at 36-37° after recrystallization from ethanol. Reported melting points for bis(phenylthio)methane are 34-35°, 38-40°, and 39.5-40.5°." The proton magnetic resonance spectrum of the product in carbon tetrachloride exhibits a two-proton singlet at 8 4.30 and a 10-proton multiplet at 8 7.10-7.56. 

The ethanolic filtrate can be concentrated to 10-15 ml. imder reduced pressure to obtain 0.3 g. (7%) of crude product, m.p. 187-202°. Unchanged starting material, if present, is concentrated in this second fraction and may be detected by the furan resonance at 8 5.86 in the proton magnetic resonance spectrum or by a sharp infrared absorption... 

The material is normally utilized directly without further purification. If the solid is very gray, it may be recrystallized. For the recrystallization the salt is dissolved in hot 95% ethanol (approximately 350 ml. per 100 g. of salt) containing decolorizing carbon, filtered rapidly, and the clear supernatant liquid is allowed to cool in a freezer (—20°). In this way, white crystals, m.p. 106-107°, may be obtained with nearly quantitative recovery. The checkers obtained the purified material of m.p. 108-109° with 95% recovery and used this material for the next step. The purified material has the following spectral data ultraviolet (95% ethanol) nm. max (e) 236 shoulder (13,200), 262 (2200), 268 (2680), 275 (1010) infrared (Nujol) cm-1 3090 weak, 3060 weak (aromatic CH), 1580 weak (C=C) proton magnetic resonance (CDCla), first-order analysis, 6 in p.p.m. 7.5-8.2 (multiplet 10H, Ha), 4.3 (poorly resolved triplet 2H, Hb), 3.75 (triplet 2H, Hd), 2-2.5 (multiplet 2H, He) coupling constant J in Hz. Jbc — 8, Jcd = 6.5. 

Fig. 3.67 Proton magnetic resonance spectrum of pure ethanol sweep width 500 Hz.

The boron cation is stable in acidic aqueous solution, somewhat less stable in water, but decomposes in alkaline solution. The proton magnetic resonance spectrum in D20 relative to external TMS shows three bands —8.60 (broad), - —8.19 (doublet, J = 7 Hz.), and —2.85 (singlet), with the expected intensities corresponding to the a- and /6-ring hydrogen atoms and the methyl group, respectively. The bromide is very soluble in cold water and hot ethanol but insoluble in acetone. The hexafluorophosphate is slightly soluble in cold water but very insoluble in acetone. 

Using proton magnetic resonance spectroscopy, Cristol and Jarvis showed that chloro-sulphone (238) epimerises in ethanol containing sodium ethoxide at room temperature, the equilibrium slightly favouring (239). When the solution is heated under reflux, a rapid gamma-elimination occurs to yield (240). 

Fig. 12.16. Analysis of the proton magnetic resonance spectrum for the liquid ethanol. (a ) The NMR experimental spectrum. From the right side the tetramethylsilane (TMSl signal the reference chemical shift taken as 5 = 0, at 5 = ] ppm the triplet signal from the protons of the CH3 group, at about 3.5 ppm a multiplet from the CH2 group, at 5 5.3 ppm there is a triplet...

More recently, Perez-Mayoral et al. reported the acetalation/ketalation of carbonyl compounds catalyzed by acid- or basic-aluminated mesoporous SBA-15 under solvent-free conditions and thermal activation in the presence of ethanol and/or triethyl orthoformate [47]. The procedure therein reported was applied to the preparation of key intermediate compounds in the symthesis of a pH indicator 8 for Proton Magnetic Resonance Spectroscopic Imaging (Scheme 5). 

FIGURE 18.7 Comparison of the proton magnetic resonance spectra of ethanol, diethyl ether, and polyfvinyl ethyl ether). (Data from Slichter, W. P., 7. Chem. Educ., 45,10 1968.)... 

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