Proton magnetic resonance

1 Experimental Aspects. A number of reviews which include discussion of the experimental aspects of NMR methods have been published (e.g., see 2159, 847, 1864, 1684, 1659a). The excellent book by Pople, Schneider, and Bernstein has a complete and authoritative chapter on H bonding, and furnishes valuable supplemental reading on all aspects of this topic (1659a). [Pg.143]

Chemical shifts are often reported in terms of the dimensionless quantity 5 [Pg.144]

H = resonance field of the compound of interest Hr = resonance field of a reference compound [Pg.144]

The reference substance varies cyclohexane is a good choice. Water is often used but may prove to be a poor reference because of temperature sensitivity of its H bonding structure. [Pg.144]

To provide an idea of magnitudes, two values can be mentioned of 5 referred to a bare proton, a proton with no magnetic shielding by electrons for cyclohexane, 5 is +27.0, and for molecular hydrogen, 5 is +27.5 (848). [Pg.144]

The principal methods for deterrnination of the deuterium content of hydrogen and water are based upon measurements of density, mass, or infrared spectra. Other methods are based on proton magnetic resonance techniques (77,78), F nuclear magnetic resonance (79), interferometry (80), osmometry (81), nuclear reaction (82), combustion (83), and falling drop methods (84). [Pg.8]

Lanosterol [79-63-0] M 426.7, m 138-140", [a] d +<52.0" (c 1, CHCI3). Recrystd from anhydrous MeOH. Dried in vacuo over P2O5 for 3h at 90°. Purity checked by proton magnetic resonance. [Pg.277]

The product can be examined for purity by proton magnetic resonance or by gas chromatography. The submitters have used XF-1150 columns successfully. Columns with polar sites will strip silyloxy groups from the bis(silyloxy) compounds and are unsatisfactory. [Pg.5]

MHz proton magnetic resonance spectrum in the region of overlapping triplets near B 3.6. [Pg.29]

The proton magnetic resonance spectrum (carbon tetrachloride) exhibits only a singlet at S 3.56. [Pg.33]

The infrared spectrum (chloroform) shows bands at 2230 (medium strong), 1348, and 940 (medium) cm. The proton magnetic resonance spectrum (chloroform-d) shows absorption at 3 5.73 and 7.33 (AA XX pattern). [Pg.35]

The yield is determined by weighing the cold trap before and after distillation of methylenecyclopropane. Any small amounts of tetra-hydrofuran carried into the methylenecyclopropane trap are eliminated in a subsequent distillation. By proton magnetic resonance analysis the checkers found that no tetrahydrofuran reached the cold traps the spectrum (dichloromethane) shows a triplet at S 1.00 and a quintuplet at S 5.35 in the ratio 4 2. [Pg.39]

A short-path distillation apparatus is used, the distillate (oxa-spiropentane plus dichloromethane) being trapped in a reeeiver placed in a methanol-dry ice bath cooled to — 80°. The checkers found it useful to drive out last traces of product by adding several milliliters of dichloromethane to the residual thick paste and distilling. The proton magnetic resonance spectrum (dichloromethane) shows an oetet at 8 0.85 and a singlet at S 3.00 in the ratio 4 2. [Pg.39]

The purity of cyclobutanone was checked by gas chromatography on a 3.6-m. column containing 20% silicone SE 30 on chromosorb W at 65°. The infrared spectrum (neat) shows carbonyl absorption at 1779 cm. - the proton magnetic resonance spectrum (carbon tetrachloride) shows a multiplet at 8 2.00 and a triplet at S 3.05 in the ratio 1 2. [Pg.39]

Proton magnetic resonance (carbon tetrachloride) B (number of, protons, multiplicity) 3.63 (2, singlet), 3.48 (2, singlet), 3.27 (6, singlet). The infrared and mass spectra are also as reported. ... [Pg.43]

The progress of this reaction may be followed either by observing the disappearance of the band at 1845 cm. in the infrared or by following the replacement of the reactant proton magnetic resonance peak (carbon tetrachloride) at S 1.55 b the product peak at S 1.50. [Pg.49]

The submitters report that this product solidifies when cooled and melts at 21-22 and that the product is stable when stored in a refrigerator. The product exhibits infrared absorption (carbon tetrachloride) attributable to C=0 stretching at 1810 and 1765 cm. and a proton magnetic resonance singlet at B 1.50 (carbon tetrachloride). The mass spectrum of the product exhibits the following relatively abundant fragment peaks m/e (relative intensity), 60(10), 59(99), 57(34), 56(86), 55(47), 50(21), 44(100), 43(30), 41(91), 40(27), and 39(61). [Pg.49]

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. [Pg.57]

The proton magnetic resonance spectrum (carbon tetrachloride) consists of a broad methine signal centered at S 2.55 and a methyl singlet at 8 1.53 superimposed upon a methylene absorption at 8 1.25-1.85. Vapor phase chromatographic analysis denoted a purity of >98%. [Pg.58]

For twice-distilled material infrared (liquid film) cm." 1745 strong, 1565 strong, 1430 medium strong proton magnetic resonance (chloro-form-d) (number of protons, multiplicity, coupling constant J in Hz) 3.14-3.45 (1, multiplet), 3.76 (3, singlet), 3,86 (3, singlet), 5.6 (1, doublet of doublets, J = 6 and 8). [Pg.62]

The mixture was characterized as follows infrared (liquid film) cm. 1745 strong (shoulder at 1720), 1640 medium strong, 1440 medium strong proton magnetic resonance (chloroform-d) B (multiplicity, number of protons) 3.75 (singlet, 6), 4.12 (singlet, 2), 6.21 and 6.30 (two singlets, 1). [Pg.65]

Proton magnetic resonance (carbon tetrachloride) 8 (multiplicity,... [Pg.70]

The ethanolie filtrate can be concentrated to 10-15 ml. under 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 5.85 in the proton magnetic resonance spectrum or by a sharp infrared absorption... [Pg.76]

The solid tenaciously holds a small amount of chloroform which can be detected by proton magnetic resonance (S 7.25). Vacuum drying overnight at 60 removes this impurity. [Pg.77]

The product has the following spectral properties infrared (chloroform) cm. 1652, 1597 proton magnetic resonance (chloroform-d) 3 1.33, 6.56. [Pg.79]

Proton magnetic resonance (carbon tetrachloride) S 3.75 (singlet with fine structure) infrared (neat) cm. 2985, 2273, 1667, 1527, 1515 fluorine magnetic resonance (carbon tetrachloride) p.p.m. (CFCI3 internal standard) 142.4 (symmetrical multiplet, 2 ortho F), 153.8 (triplet with flne structure, 1 para P, J = 20 Hz), 161.7 (multiplet, 2 meta F). [Pg.82]

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