Resonant spectrum

MHz proton magnetic resonance spectrum in the region of overlapping triplets near B 3.6. 

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

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). 

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. 

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. 

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. 

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%. 

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... 

The product is a mixture of at least two diasteriomers as indicated by its proton magnetic resonance spectrum (carbon tetrachloride) showing eight singlets at S 0.9-1.22 for a total of twelve methyl protons. Its ir spectrum (neat) exhibits absorption bands at 3440 and 1695 cm. 

Fig. 2. The proton magnetic resonance spectrum of 5-nitrobenzofuroxan, in acetone at — Sl C. The bands marked by arrows arise from the 5-nitro tautomer.

This formulation is supported by the proton resonance spectrum of the trifluoromethyl compound 101 which shows that it exists in the CH form shownd However, strong electron-withdrawing groups in the 4-position apparently lead to enolization, and compound 102, for example, gives an intense color with ferric chloride, - Other 4-acylated oxazol-5-ones are often formulated as 103 (see, e.g, reference 113). Tautomerism of the type illustrated by the equilibrium 104 103 has been discussed (see reference 115 for further references). 

C Nuclear magnetic resonance spectrum, acetaldehyde, 732 acetophenone, 732 anisole, 672 benzaldehyde, 732 benzoic acid, 771 p-bromoacetophenone, 449 2-butanone, 449, 732 crotonic acid. 771 cyclohexanol, 634 cyclohexanone, 732 ethyl benzoate, 477 methyl acetate, 443 methyl propanoate, 450 methyl propyl ether, 672... 

Nuclear magnetic resonance spectrum, acetaldehyde, 731 anethole, 683 bromoethane, 460... 

Mathematical models are the link between what is observed experimentally and what is thought to occur at the molecular level. In physical sciences, such as chemistry, there is a direct correspondence between the experimental observation and the molecular world (i.e., a nuclear magnetic resonance spectrum directly reflects the interaction of hydrogen atoms on a molecule). In pharmacology the observations are much more indirect, leaving a much wider gap between the physical chemistry involved in drug-receptor interaction and what the cell does in response to those interactions (through the cellular veil ). Hence, models become uniquely important. 

Figure 7-34. 2-PADMK specify of 10 mol% C(1 DOO-PPV, measured al the peak of Ihc spin-1/2 signal (polarons) or the broad resonant spectrum (polaron pairs). The H-PADMR spectrum is inset.

Vervoort, J., et al. (1986). Identification of the true carbon-13 nuclear magnetic resonance spectrum of the stable intermediate II in bacterial luciferase. Biochemistry 25 8062-8067. 

Figure 1. Nuclear magnetic resonance spectrum of abscisin II in CDCh...

Vinylacetio acid is available from Toltyokasei Company, Ltd., Japan or from Fluka AG, Buchs, Switzerland. Commercial material, which shows about 3% of crotonic acid [2-Butenoic acid, (A)-] in its proton magnetic resonance spectrum, was distilled at 90-92° (40-43 mm.) prior to use. 

Gas chromatographic analysis of the product showed two major peaks (relative intensity, 5 1), and the mass spectrum of each peak revealed a molecular ion at i/e 210. The proton magnetic resonance spectrum of the mixture showed that the two products were geometrically isomeric esters. 

Spectra. The UV spectra in w, acid, and base are given in Ref 5. The proton nuclear magnetic resonance spectrum shows a sharp singlet at 3.90ppm from te tram ethyl silane (Ref 15)... 

The proton magnetic resonance spectrum (benzene-d6) indicated the presence of less than 5% p-benzoquinone. This material darkens upon standing even in a refrigerator recrystallization should be performed as soon as possible. 

The pure adduct had the following proton magnetic resonance spectrum (chloroform-d) <5, multiplicity, number of protons, assignment 6.75 (singlet, 2, cyclohexene vinyl protons), 6.20 (multiplet, 2, cyclobutene vinyl protons), 3.5 (broad multiplet, 4, cyolobutane protons). 

A 100 MHz. proton magnetic resonance spectrum (chloroform d) of the amine in the presence of an equal amount of the chiral shift reagent, tris[3-(trifluoromethylhydroxymethylene)-d-camphorato]euro-pium(III)4 (submitters), or in the presence of an equal amount of tris[3-(heptafluoropropylhydroxymethylene)-d-camphorato]europium-(III) (checkers), revealed that the product contained no detectable enantiomeric isomer. 

The a-plienylcinnamonitrile (Note 4) present in the distillation flask can be recovered. The residue is broken up with 75 ml. of methanol, the mixture stirred and cooled, and the product recovered by filtration. Recrystallization from methanol gives 17-20 g. of crystalline material, m.p. 86-88°. The proton magnetic resonance spectrum (chloroform-d) shows complex multiplets at 5 7.20-8.00. 

The distilled product has the following proton magnetic resonance spectrum (chloroform- ) (5, number of protons, assignment ... 

Fig. 5. Solid-state i C nuclear magnetic resonance spectrum of corn cob xylan.

Fig. 6. The electron-paramagnetic resonance spectrum of Kpl in frozen solution at 10 K.

Estimated from the proton magnetic resonance spectrum. 

The checkers obtained 12.8-13.0 g. (52-53%), m.p. 84-86°, in the first crop and 2.7-3.4 g. (11-14%), m.p. 52-62°, in the second crop. Recrystallization of the former from methanol gave 11.5 g. of crystals, m.p. 84-86°, suggesting that the first crop is a pure single isomer. A proton magnetic resonance spectrum in chloroform-d of the second crop shows two singlets at 8 1.62 and 1.64 for the terf-butyl groups. Thus this material is a mixture of syn and anti isomers. Both the first and second crops proved equally useful for tcrf-butoxycarbonylation of an amino acid. 

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