Tubes Wilmad

NMR instrument Norell sample tube Wilmad sample tube... 

In a typical experiment 0.8 mL portions of solutions made from 0.029 g (p-pdt)[Fe(CO)2(PMe3)]2 in 1 mL CH2C12 were placed in medium-pressure NMR sample tubes (Wilmad, 528 -PV-7) together with 2 pL H20. The tubes were degassed, pressurized with 10 bar D2 and exposed to sunlight as shown in Fig. 2. 2H NMR spectra were taken at time intervals to follow the formation of HOD. 

Sample oreDaration. Zeolite H-ZSM-11 (Si/AI=25) was prepared by ammonium-exchange of Na-ZSM-11 and calcination at 823 K in air. The powdered samples (0.09 0.01 g) were packed into NMR tubes (Wilmad, 5 mm o.d. or 5.6 mm o.d. with constrictions). After 8 h heating at 573 K the catalysts were evacuated to a final pressure of 6-10 Torr and cooled down to room temperature before adsorption. 

Organometallic samples for NMR spectroscopic measurements were prepared in the glove box by use of J. Young valve NMR tubes (Wilmad 528-JY). H and NMR spectra were recorded on a Bruker-400 spectrometer (FT, 400 MHz for H 100 MHz for or a JEOL-AL300 spectrometer (FT, 300 MHz for H 75 MHz for at room temperamre, unless otherwise noted. High-resolution mass spectra (HRMS) were recorded on a Bruker Apex IV FTMS mass spectrometer using ESI (electrospray ionization). Microelemental analyses were performed on an Elemental Analyzer Vario EL apparatus. 

NMR tubes 5 mm OD NMR tubes (Wilmad-LabGlass) in 96-tube rack. 

The normal Fourier transformed proton decoupled spectra of the solid elastomers were obtained on a Broker HX-90-E/SXP spectrometer with a 15-inch magnet. The solid samples were cut into small pieces and placed into the inner portion of a 7 mm ID Wilmad coaxial tube. The upper portion of the inner coaxial tube was 9 mm ID and fits precisely inside a standard 10 mm Wilmad tube which contained the high temperature lock compound. Depending on the desired temperature, either D2O, DMSO-de or 1,4-dibromotetra-deuterobenzene was used as the lock. Ninety degree pulse widths of less than 15 ps were used with a five second repetition time,... 

Data provided by the NMR sample tube producers Wilmad and Norell. 

ESR spectrometer (a relatively inexpensive teaching instrument is available from Micro-Now Instruments, Skokie, IL) 2.5-mm-OD ESR tube (or special ESR tube for aqueous samples) (Wilmad) 5-mL syringe five 10-mL beakers. 

The samples for NMR spectroscopy were prepared in Wilmad 528-PP 5 mm Pyrex NMR tubes using deuterochloroform as solvent (0.7 mL). The NMR spectra ( H-NMR, C-NMR, DEPT-135) were acquired on a Broker AM-360 spectrometer equipped with a quadrinuclear 5 mm probe head, at 360.13 MHz for H and at 90.03 MHz for C under standard conditions 12). All chemical shifts are cited in ppm relative to the solvent signal. 

We have found that Wilmad (507 pp) NMR tubes provide adequate resolution for routine high field NMR spectra. 

We use the highest quality NMR tube we can afford. We match the diameter of the sample tube to the coil diameter of the NMR probe in the magnet. We do not put a 5 mm tube in a 10 mm probe unless we have no choice, and we NEVER use an NMR tube with a diameter larger than that the probe is designed to accommodate For most organic samples comparable to those whose spectra are found in this book, a Wilmad 528-pp or similar tube suffices. Cheap tubes contain regions where the tube wall thickness varies, and this variation makes our sample not just difficult, but nearly impossible, to shim well. Variations in concentricity, camber, and diameter all limit data quality. Those interested in saving a little on tubes should examine Equation 2.1 where t is time and is money and do the math for themselves—we can spend an extra 10 on our tube or we can shim for an hour. Consider that tubes are reusable and that the extra cost associated with the purchase of a quality NMR tube can be amortized easily over the course of several years. 

NMR tubes can be tested for camber and concentricity by using an NMR tube checker. These tube checkers are available from Wilmad and other vendors. 

The [(CAAC)AuClj complex (15 mg) and the appropriate amount of an alkyne or an allene were loaded into a Wilmad quick pressure valve (QPV) thick-walled (1.4mm) NMR tube. CgDg (0.4ml) and the internal standard, benzyl methyl ether (5 mg), were added to the mixture. For experiments with a low catalyst loading (0.1 mol%), 3 mg of the catalyst and 0.1 ml of C5D5 were used. The NMR tube was connected to a high-vacuum manifold, and excess NHj (typically 3-6equiv.) was carefully condensed at —60°C. The tube was sealed, placed in an oil bath behind a blast shield, and heated at the specified temperature. (Caution Sealed NMR tubes containing NHj and/or 1,2-propadiene are under high pressure and pose an explosion hazard. Only new tubes with a wall thickness of at least 1.4 mm should be used). 

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