Tetramethylsilane , reference

If all the pentane is removed before pyrolysis, the bicyclo [2.1.0]pentane shows no impurities on vapor phase chromatography with a 20% Dow 710 on 50/60 U Anaprep column. Analysis by n.m.r. also revealed the absence of any traces of cyclo-pentene in the spectrum consisting of three complex multiplets at 0.3-0.8, 1.1-1.7, and 1.9-2.4 p.p.m. (downfield from internal tetramethylsilane reference). 

No attempt was made to further purify this compound, which had a very characteristic n.m.r. spectrum (deuterio-chloroform solution, external tetramethylsilane reference) 1.22 (doublet, J = 7.5 Hz., 3H), 1.37 (doublet, J = 7.5 Hz., 3H),... 

Nuclear magnetic resonance spectrum (deuteriochloroform-solvent, internal tetramethylsilane reference) multiplet at... 

The n.m.r. spectrum (carbon tetrachloride solution, tetramethylsilane reference) shows a broad singlet centered at... 

The simplest and most accurate way to determine the composition of the product is by proton n.m.r. spectroscopy. The ratio of the oxirane hydrogen atoms cis 4.48 p.p.m. and trans 3.97 p.p.m. downfield from internal tetramethylsilane reference, determined in carbon tetrachloride or deuteriochloro-form solution)3 gives directly the ratio of the isomers. Infrared... 

The submitters found that analysis of the final product by gas chromatography indicated a 15% contaminant of the by-product, cyclohexenylacetaldehyde. The analysis was conducted on a column packed with 5% XE-60 on Chromosorb W at 120°. The retention times for cyclohexenylacetaldehyde and cyclohexylideneacetaldehyde were 1.3 and 3.3 minutes, respectively. The checkers found that the product contained 10-15% of cyclohexenylacetaldehyde by gas chromatographic analysis and 12-16% by n.m.r. spectral analysis (deuteriochloro-form solution, tetramethylsilane reference), using the relative intensity of two signals (8 9.53 and 9.97) due to the aldehydic protons of the two compounds. Reported physical constants are b.p. 58-62° (16 mm.) for cyclohexenylacetaldehyde and b.p. 80-85° (16 mm.) for cyclohexylideneacetaldehyde.4... 

Fig. ]3. NMR spectra of methyl methacrylate polymers prepared with (a) benzoyl peroxide in toluene at 100° and (i6J w-butyllithhim in toluene at —62°. The spectra are run on 15% solutions of the polymers in chloroform with 1% tetramethylsilane reference (r)...

The complexes (l,5-cyclooctadiene)(2,4-pentanedionato)-palladium(II) and platinum(II) tetrafluoroborate are air-stable solids, soluble in polar organic solvents such as chloroform, methylene chloride, acetonitrile, acetone, or methanol but insoluble in nonpolar solvents such as alkanes, benzene, or ether. Their solutions in acetone have conductivities typical of 1 1 electrolytes. Their proton magnetic resonance spectra (in CDC13 solutions, internal tetramethylsilane reference at 60 MHz.) show peaks due to coordinated cyclooctadiene at 3.78 and 6.7-7.4r (Pd) and at 4.25 and 6.9-7.6r (Pt) and due to the chelated /3-diketone at 4.39 and 7.88r (Pd) and at 4.15 and 7.81r (Pt) with the expected area ratios. In the spectrum of the platinum compound coupling with the 95Pt isotope (33 %... 

Chloro(l,5-cyclooctadiene) (triphenylarsine)platinum(II) tetrafluoroborate is a white, air-stable solid. It is sparingly soluble in polar organic solvents and insoluble in nonpolar ones. A 10-3 M solution in acetone shows a conductivity characteristic of a 1 1 electrolyte.1 Its proton magnetic resonance spectrum (in liquid sulfur dioxide solution, at 60 MHz., with internal tetramethylsilane reference) shows bands due to the coordinated olefin at 3.59 [two protons 55 Hz.], 5.01 [two... 

FIG. 2. Temperature dependence of the C NMR frequency in K3C40 and RbsCw, reported as the shift relative to a tetramethylsilane reference signal. 

Fig. 2 shows the proton magnetic resonance spectrum of halothane. This spectrum was obtained on a carbon tetrachloride solution, using a Varian HA-100 instrument, with a tetramethylsilane reference. The quartet centered at 5.76 p.p.m. is assigned to CH adjacent to a CFo group (4). 

Fig. 2. Nuclear magnetic resonance spectrum of halothane in carbon tetrachloride, tetramethylsilane reference (courtesy of Dr. J. M. Pryce).

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