Tetramethylsilane , nuclear magnetic

Tris(dimethylamino)arsine (d2o 1.1248 nd 1.4848)3 is a colorless liquid which is readily hydrolyzed to form arsenic (III) oxide and dimethylamine when brought into contact with water. The compound is soluble in ethers and hydrocarbons. The product is at least 99.5% pure (with respect to hydrogen-containing impurities) as evidenced by the single sharp peak at —2.533 p.p.m. (relative to tetramethylsilane) seen in the proton nuclear magnetic resonance spectrum of the neat liquid. 

The nuclear magnetic resonance spectrum of sodium valproate as shown in Figure 3 was obtained on a Varian Associates T-60 NMR Spectrometer in deuterium oxide containing tetramethylsilane as the internal standard. The spectral peak assignments (2) are presented in Table I. 

Since the product slowly darkens on exposure to air, it should be stored under nitrogen in a refrigerator. The compound solidifies on cooling m.p. 16.0-16.5°. Nuclear magnetic resonance spectrum (neat, tetramethylsilane internal standard) singlets at d 7.00 (aromatic protons), 3.93 (CH2), and 2.24 p.p.m. (NH). 

Infrared (IR) spectra were measured on a Beckmann Microlab 600 model spectrophotometer. Nuclear magnetic resonance (NMR) spectra were measured on a Varian EM360 spectrometer, with 19F-spectra collected using trifluoroacetic acid as a standard, or with H-spectra collected using tetramethylsilane as a standard. 

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

The H nuclear magnetic resonance spectrum of chlorpromazine hydrochloride in CDCI3 is shown in Figure 5 [13]. The data were recorded on a Varian XL 200 MHz spectrometer using tetramethylsilane as the internal reference. Assignments for the observed resonance bands are presented in Table 3. 

All NMR spectra were recorded on a Varian A-60 spectrometer at room temperature by Nuclear Magnetic Resonance Specialties, Inc., New Kensington, Pa. Benzene soluble fractions were recorded in deuterated chloroform solution (CDCls) while dimethyl sulfoxide-dc (DMSO-dr.) was the solvent employed for other fractions. (Deuterated chloroform with enrichment of 99.8% was purchased from Bio-Rad Laboratories and dimethyl sulfoxide-dr, with enrichment of 99.6% from Merck, Sharp, and Dohme of Canada.) The internal standard used with the CDCla solutions was tetramethvlsilane and hexamethyl-disiloxane (chemical shift 7 c.p.s.) with DMSO-d . Prior to preparation for NMR recording, the samples were thoroughly dried in a vacuum at 110°C. The NMR tubes were sealed to minimize the absorption of atmospheric moisture. The chemical shifts given in c.p.s. are referred to tetramethylsilane. 

H NMR spectrum The proton nuclear magnetic resonance (1H NMR) spectrum of omeprazole were obtained using a Bruker Instrument operating at 300,400, or 500 MHz. Standard Bruker Software was used to execute the recording of DEPT, COSY, and HETCOR spectra. The sample was dissolved DMSO-d6 and all resonance bands were referenced to tetramethylsilane (TMS) as internal standard. The H NMR spectra of omeprazole are shown in Figs. 4.9-4.12 and the COSY H NMR is... 

Nuclear magnetic resonance (NMR) spectrometry [4] Both the 1H NMR and 13C NMR spectra of zaleplon have been obtained in DMSO- as a solvent and using tetramethylsilane as the internal standard (IS). The assignments for both the 1H and 13C NMR spectra make use of the following numbering scheme ... 

The following tables give the region of the expected nuclear magnetic resonance absorptions of major chemical families. These absorptions are reported in the dimensionless units of parts per million (ppm) vs. the standard compound tetramethylsilane (TMS), which is recorded as 0.0 ppm ... 

The FI and 13C nuclear magnetic resonance spectra of aspartame are shown in Figures 6 and 7, respectively. These spectra were obtained from a d6-DMSO solution (7.5 mg/mL) using a Bruker Avance DRX-500 spectrometer. All spectra were referenced to tetramethylsilane, and assignments for the H-NMR and 13C-NMR spectra are found in Tables 2 and 3, respectively. 

Nuclear Magnetic Resonance Spectroscopy. Nmr is a most valuable technique for structure determination in thiophene chemistry, especially because spectral interpretation is much easier in the thiophene series compared to benzene derivatives. Chemical shifts in proton nmr are well documented for thiophene (CDC13), 6 = H2 7.12, H3 7.34, H4 7.34, and H5 7.12 ppm. Coupling constants occur in well-defined ranges J2 3 = 4.9-5.8 J3 4 = 3.45-4.35 J2 4 = 1.25-1.7 and J2 5 = 3.2-3.65 Hz. The technique can be used quantitatively by comparison with standard spectra of materials of known purity. 13C-nmr spectroscopy of thiophene and thiophene derivatives is also a valuable technique that shows well-defined patterns of spectra. 13C chemical shifts for thiophene, from tetramethylsilane (TMS), are C2 127.6, C3 125.9, C4 125.9, and C5 127.6 ppm. 

Fig. 3. —Nuclear Magnetic Resonance Spectrum of Methyl 5-Acetamido-5-deoxy-2,3,4-tri-O-methyl-a-D-xylopyranoside (210). [Taken at 100 MHz in tetiachloroethane at 35°, lower curve at 110°, upper curve tetramethylsilane as internal standard.]...

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 tetramethylsilane (Ref 15)... 

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

The nuclear magnetic resonance (NMR) spectrum (Fig. 2) was obtained by preparing a saturated solution of meperidine hydrochloride, U.S.P. (Wyeth Lot No. F-665901) in deutero chloroform containing tetramethylsilane as internal reference. The only exchangeable proton is the hydrogen associated with HC1. The NMR proton spectral assignments are given in Table II. 

Three techniques were used to determine the structure of each chemical made. For each new analog, an H NMR (nuclear magnetic resonance) analysis of a 25 mg sample was run on a Nicolet 300 MHz NMR spectrometer. The sample was dissolved in CDCI3 with tetramethylsilane (TMS) as a reference. 

Instruments Batch experiments for obtaining CL profiles were performed using a Microtec NITI-ON Lumicounter 2500 (Chiba, Japan). Proton nuclear magnetic resonance ( H-NMR) spectra were obtained on a JEOL JNM-EX270 spectrometer (Tokyo, Japan) with tetramethylsilane as an internal standard. Mass spectra (FAB-MS) were measured on a JEOL JMS-LXIOOO (Tokyo, Japan) with w-nitrobenzyl alcohol as a matrix. 

Abbreviations NMR, nuclear magnetic resonance PMR, proton magnetic resonance ppm, parts per million TMS, tetramethylsilane MW, molecular weight EPR, electron paramagnetic resonance CD, circular dichroism ORD, optical rotatory dispersion HiPISP, high potential iron-sulfur portein. 

The nuclear magnetic resonance (NMR) spectra were recorded on a Varian A-60 spectrometer, using deuterated dimethyl sulfoxide (DMSO) as solvent and tetramethylsilane as internal standard. IR spectra were obtained on a Perkin-Elmer 237B IR spectrophotometer. 

Nuclear magnetic resonance analysis with double and triple resonance was used to elucidate the structure as 3, 4 -dideoxykanamycin B 2"-adenylate. The spectrum of the inactivated 3, 4 -dideoxykanamycin B in deuterium oxide at pH 8.0, with tetramethylsilane as the external reference standard (8 =0), showed signals at 8 8.63 and 8.85 attributable to the adenine-ring protons, and at 8 6.53, 5.28, 4.98, 4.83 and 4.6 (H-2) the latter were assigned to the D-ribose-ring protons by successive doubleresonance experiments, and by comparison with disodium 5 -adenylate in deuterium oxide. Therefore, these observations confirmed the presence of one molecular proportion of 5 -adenylic acid in the molecule. Irradiation at 8 5.45 (7 3.6, H-1") caused the complex signal at 8 4.3 (H-2")... 

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