Polypropylene vessels

HF, CH3CN. In certain sensitive substrates it may be advisable to run this reaction in a polypropylene vessel, as was the case in Schreiber s synthesis of FK-506, where the yield increased from 35% to 73% after switching from the standard glass vessel. This is presumably because of the products formed when HF reacts with glass. 

The reaction vessels were removed from the reaction module, placed in a shaker rack and treated with 1.00 mL of 9.3 mM HMDS in TFA/CDC13 (1 1). After shaking for 1 h, the contents of the vessels were transferred to 15 mL polypropylene vessels equipped with a filter frit, and the filtrate was collected in 4 mL analytical vials. The cleaved resins were washed three times with... 

MPA (450 mg, 1.2 mmol) in DMSO (13 mL) was added. After adjusting the pH again to 7, 52 mL of horse liver S9 preparation was added. The reaction mixture was distributed into nine polypropylene vessels in equal portions ( 29 mL) and incubated under gentle magnetic stirring in a temperature-controlled incubator at 25 °C for 20 h. 

M. R. Masson, Cahbration of Plastic Laboratory Ware, Talanta, 28 (1981) 781. Tables for use in calibration of polypropylene vessels are presented. 

Synthesis of the incorporated phthalocyanine Ludox As 40 (92.5 g), tetraethylammonium hydroxide (92.5 g of a 20 wt.% solution in water) and deionized water (75 g) were placed in a polypropylene vessel and stirred at room temperature for 22 h. A mixture of CTAC (5 g of a 25 wt.% solution in water) and one of the phthalocyanines ( 300 mg, -0.25 mol) was added slowly (5 mL min ) to gel (10.4 g) with stirring. This mixture was stirred for 15 min and aged overnight at room temperature. The composition of the final gel mixture was 9.61% SiOz, 4.8% TEAOH, 77.47% H2O and 8.12% CTAC. The mixture was reacted without stirring for 40 h at 100 °C in a polypropylene autoclave. The resulting green product was recovered by filtration and washed intensively with water and hot ethanol. The MCM-41 structure was proven by X-ray diffraction. The content of the phthalocyanine in the molecular sieve is -10 mol g. ... 

CHAPTER TWENTY-FIVE Failure of a Polypropylene Vessel... 

Failure in a polypropylene vessel, 295-304 bubble collapse, 303 failure incident, 297 fracture calculations, 299-304 investigation of failure, 298 plant layout, 295 Family moulds, 14 Fibre reinforcement, 160 Fibreglass Ltd, 128 Fibrelam aircraft flooring, 211-20... 

Preparation of Maleimide- (M) and Peptide- (or L-Cysteine-) Modified (P) Samples. Twenty silanized titaniiun samples (A) were placed in a self-fabricated polypropylene vessel with 2 mL of acetonitrile (CH3CN) containing 5.0 mM cross-hnkers. After incubation at 20 °C for 30 min, with 30 s of sonication every 10 min, the excess cross-linker solution was removed and the samples were washed extensively with acetonitrile, acetone, and hexane. After they were dried with N2, the samples were subject to the next chemical step. Twenty maleimide-grafted substrates were incubated at 20 for 1 h in... 

Fep2 was first prepared by the action of gaseous hydrogen fluoride over FeCl2 ia an iron boat (2). The reaction of anhydrous FeCl2, FeCl2 4H20, or FeSO and anhydrous HF in plastic reaction vessels such as vessels of polyethylene, polypropylene, or Teflon results in quantitative yields of very... 

Hydrofluoric acid [7664-39-3] M 20.0, b 112.2"(aq azeotrope, 38.2% HF), d 1.15 (47-53% HF), pK 3.21. Freed from lead (Pb ca 0.002ppm) by co-precipitation with Srp2, by addition of lOmL of 10% SrCl2 soln per kilogram of the cone acid. After the ppte has settled, the supernatant is decanted through a filter in a hard-rubber or paraffin lined-glass vessel [Rosenqvist Am J Sci 240 358 1942. Pure aqueous HF solutions (up to 25M) can be prepared by isothermal distn in polyethylene, polypropylene or platinum apparatus [Kwestroo and Visser Analyst 90 297 7965]. HIGHLY TOXIC. 

A cylindrical polypropylene pressure vessel of 150 mm outside diameter is to be pressurised to 0.5 MN/m for 6 hours each day for a projected service life of 1 year. If the material can be described by an equation of the form s(t) = At" where A and n are constants and the maximum strain in the material is not to exceed 1.5% estimate a suitable wall thickness for the vessel on the assumption that it is loaded for 6 hours and unloaded for 18 hours each day. Estimate the material saved compared with a design in which it is assumed that the pressure is constant at 0.5 MN/m throughout the service life. The creep curves in Fig. 2.5 may be used. 

A powder was emptied down a metal duct into a plant vessel. The duct was replaced by a rubber hose, as shown in Figure 15-2. The flow of powder down the hose caused a charge to collect on it. Although the hose was reinforced with metal wire and was therefore conducting, it was connected to the plant at each end by short polypropylene pipes that were nonconducting. A charge therefore accumulated on the hose, a spark occurred, the dust exploded, and a man was killed. 

The high-purity water thus produced typically has a conductance of about 0.5 x 10-6fi-1cm-1 (0.5juScm-1) and is suitable for use under the most stringent requirements. It will meet the purity required for trace-element determinations and for operations such as ion chromatography. It must however be borne in mind that such water can readily become contaminated from the vessels in which it is stored, and also by exposure to the atmosphere. For the determination of organic compounds the water should be stored in containers made of resistant glass (e.g. Pyrex), or ideally of fused silica, whereas for inorganic determinations the water is best stored in containers made from polythene or from polypropylene. 

In 2003, the microwave-assisted coupUng of aryl hahdes with acetylenes using a palladium catalyst were carried out employing a modified Smith Process vial [49]. These vessels, equipped with a polypropylene frit and screw cap at the bottom, and sealed with an aluminum crimp cap fitted with a silicon septum at the top (Fig. 8), faciUtated the processing of approximately 1 g of solid support. Notably, they are compatible with stirring of the reaction mixture and monitoring of the temperature and pressure. 

The biberty (Fig. 10), a monomode microwave reactor for automated SPPS, was recently introduced by the CEM Corporation [153]. Although this instrument was originally developed for SPPS, it also allows for a broader scale of solid-phase applications. The solid-phase vial is equipped with a polypropylene frit and cap at one end (the entire assembly fitting into the standard 10 mb CEM reaction vessel) to allow the processing of 0.1 to 1.0 mmol quantities of resin attached substrates. An integrated fiber optic probe provides... 

A simple predecessor of the CEM setup for microwave-mediated SPOS was employed by Murray and Gellman in their synthesis of 14-hehcal 6-peptides [42], A 4 mL polypropylene solid-phase extraction tube was inserted into a 10 mL CEM vessel, allowing for both microwave heating and simple resin manipulation (Eig. 11). While using this setup gave reproducible results for their experiments, a discrepancy between the reactions target (set) temperatures and the actual temperatures was observed. Therefore, use... 

Concentrate the sample (remove acetone) under nitrogen to ca 20-25 mL using a TurboVap (water-bath at 50 °C). Transfer the sample into a 50-mL polypropylene centrifuge tube. Rinse the TurboVap vessel with 5 or lOmL of pFI 6 buffer solution. The amount of pH 6 buffer required depends on the matrix being analyzed and should be determined as needed. All matrices need 5 mL of the buffer solution to adjust the sample to pH 6, except for sweet corn (ears, forage, and stover), which requires 10 mL. Add the rinse buffer to the sample. Rinse the TurboVap vessel with 10 mL of hexane and add the hexane to the sample. 

Although PFE lacks a proven total concept for in-polymer analysis, as in the case of closed-vessel MAE (though limited to polyolefins), a framework for method development and optimisation is now available which is expected to be an excellent guide for a wide variety of applications, including non-polyolefinic matrices. Already, reported results refer to HDPE, LDPE, LLDPE, PP, PA6, PA6.6, PET, PBT, PMMA, PS, PVC, ABS, styrene-butadiene rubbers, while others may be added, such as the determination of oil in EPDM, the quantification of the water-insoluble fraction in nylon, as well as the determination of the isotacticity of polypropylene and of heptane insolubles. Thus PFE seems to cover a much broader polymer matrix range than MAE and appears to be quite suitable for R D samples. 

However, several articles in the area of microwave-assisted parallel synthesis have described irradiation of 96-well filter-bottom polypropylene plates in conventional household microwave ovens for high-throughput synthesis [16-19]. While some authors have not reported any difficulties associated with the use of such equipment [19], others have experienced problems in connection with the thermal instability of the polypropylene material itself [17] and with respect to the creation of temperature gradients between individual wells upon microwave heating [17, 18]. While Teflon (or similar materials such as PFA) can eliminate the problem of thermal stability, the issue of bottom-filtration reaction vessels has not yet been adequately addressed. 

An interesting article by O Shea and coworkers described the construction and use of a parallel polypropylene reactor comprising cylindrical, expandable reaction vessels with porous frits at the bottom [20], During the reaction, the piston of each... 

A prototype of a microwave reaction vessel that takes advantage of bottom filtration techniques was presented by Erdelyi and Gogoll in a more recent publication. Therein, the authors described the use of a modified reaction vessel (Fig. 7.2) for the Emrys instruments (see Section 3.5.1) with a polypropylene frit, suitable for the filtration /cleavage steps in their microwave-mediated solid-phase Sonogashira coupling (see Scheme 7.19) [21]. 

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