Pyrex reaction vessels

One disadvantage to using external light sources is that for irradiations using 2537-A light, a Pyrex reaction vessel cannot be used since Pyrex absorbs strongly at wavelengths less than 3000 A. Therefore more expensive quartz vessels must be used. 

In relation to sample preparation, Raman spectra can be obtained from pure complexes in the bulk state, seeing that for better performance the careful grinding of samples is required. Contrary to FTIR spectroscopy, where samples are mixed with mineral oil (Nujol) or KBr pellets, in Raman spectroscopy a pure substance is used. For this reason, the Raman spectroscopy is called a nondestructive measurement method. Additionally, analysis can be carried out through many containers such as glass, Pyrex reaction vessels, plastic containers, and so on. 

A. 3-(l-Hyivoxybutyl)-l-methyl-pyrvole (1). A photochemical quartz immersion well (220 mu length) (Note 1) equipped with 450-watt Hanovla medium pressure mercury lamp and a Vycor filter, cooled with water, 1s used. To a 125-mL Pyrex reaction vessel (230 mn long, 64 mm i.d.) equipped with a gas inlet and outlet, is added 60 rriL (55 g, 0.676 mol) of 1-methylpyrrole (Note 2)... 

Measurements by Lewis and von Elbe [23] of initial reaction rates at 530 °C in a KCl coated Pyrex reaction vessel of diameter 7.4 cm are shown in Fig. 6. For constant total pressure, the rate varies little in hydrogen-rich mixtures but diminishes when the oxygen content increases. The reaction seems more sensitive to the total pressure than it is to mixture composition. The rate diminishes with pressure until the neighbourhood of the second explosion limit is reached. At the limit itself the rate becomes infinite, and very near the limit, within a few torr, Lewis... 

Effect of inert gases on the second ignition limits of 2C0 + O2 containing small amount of hydrogen [369]. (Pyrex reaction vessel, 27.0 mm. diameter concentration of 2C0 + 02 = 50.0 torr concentration of hydrogen = 2.0 torr.)... 

Fig, 61. Effect of added hydrogen on the ignition limits of 2CO + O2 in a flow system (after Buckler and Norrish [368]). Pyrex reaction vessel, diameter 27.0 mm. (By courtesy of The Royal Society.)... 

A more direct study of the reaction between CO and NO2 was made by Brown and Crist [485], who used a KCl coated Pyrex reaction vessel fitted with a greaseless valve to avoid decomposition of the NO2. In order also to avoid complications due to gas phase dissociation of the NO2, its pressure was kept very low (<0.5 torr), and the reaction times were kept comparatively short. Amounts of reaction were measured by freezing and then analyzing for the product CO2 by vacuum sublimation from the nitrogen oxides. In order to obtain measurable amounts of reaction under the conditions stated, it was necessary to employ high concentrations of CO. Even then the partial pressures of CO2 in the products were less than 30 microns, and often as little as 5 microns, so that good experimental technique was required. It was confirmed that the reaction was second order over some two- to three-fold variation of the partial pressures of CO and NO2. Mean rate coefficients between 500 and 563 K are given in Table 57. 

Fig. 8. The temperature—pressure ignition diagram for mixtures of 3-ethylpentane and oxygen in the molar ratio 1 2. Cylindrical pyrex reaction vessel, volume 280 cm . (From ref. 85.)...

Temp. (°C) n-Pentane oxygen Pyrex reaction vessel 250 3 4 Untreated 250 2 1 Untreated 257 2 1 HF treated... 

Fig. 33. Propane—oxygen. Molar ratio 1 1 cylindrical pyrex reaction vessel, volume 150 cm. (From ref. 119.)...

Molar ratio 3 4 spherical pyrex reaction vessel, volume... 

Fig. 41. Neopentane—oxygen. Molar ratio l 2 spherical pyrex reaction vessel, volume 450 cm. The dotted curves are contours of equal rate of pressure rise at the cool flame. (From ref. 55.)...

The ignition di am for diethyl ether—oxygen mixtures has been determined [68] and the slow combustion has been studied in some detail. The low temperature oxidation becomes appreciable at 120 °C and Lemay and Ouellet [69], working at 160—175 °C which was below the lower limit of cool flame for in their pyrex reaction vessel, observed an initial pressure drop during which oxygen was consumed by a zero-order process with an activation energy of about 50 kcal. mole. Peroxides... 

The most satisfactory method, which can also be used to prepare gram quantities, is to heat the vacuum-dried hydrous oxide in a sealed, evacuated Pyrex reaction vessel with thionyl chloride vapor at 350°-500°C, the volatile, yellow pentachloride (m.p. 306°C) being obtained in better than 95% yield (47). Thermal decomposition of SO(PaCl6)2 is less satisfactory (15) and only gives a partial yield of the pentachloride, leaving an unidentified black residue. 

This compound has been photolyzed in the gas phase with a Pyrex reaction vessel and a medium pressure mercury arc without the use of any filters. Under these conditions the effective radiation is that emitted between 290 and 334 ray in the mercury spectrum with the major contribution from the lines at 313 m,u. The volatile products produced were ethylene, acetylene, hydrogen, and nitrogen. To explain the relative yields of these compounds the following mechanism was suggested ... 

Walker and coworkers have used gas chromatographic (GC) end-product analysis to investigate initiation in propene [2] and formaldehyde [3] oxidation, systems in which, for different reasons, rapid chain oxidation can be prevented. The experimental technique is deceptively simple, consisting of a heated pyrex reaction vessel, coated with aged boric acid, from which samples can be taken for GC analysis. For the initiation of propene/oxygen mixtures in the temperature range 673-793 K, the major hydrocarbon product is hexa-1,5-diene (HDE) and the reaction scheme can simply be written as. 

Prior use the 5 L Pyrex reaction vessel is cleaned (cone. 

It is very unusual that a polymer obtained tinder such mild conditions in the absence of initiator should exhibit a spin density as high as lO to 10 9 spin/g. The spin concentration for polyphenylacetylene is about 1.5 x 101 spin/g in the high-temperature limit (22) while the maximum radical concentration of carbonaceous materials obtained under the optimum conditions with an optimum heat treatment temperature of 550°C is 6 x 1019 spins/g (23). The polymer samples were prepared under contamination free conditions, i.e. pure monomer introduced under high vacuum in the absence of initiator to a pyrex reaction vessel. 

Emrys Optimizer 2-5 mL pyrex reaction vessel equipped with a stir bar and purged under argon... 

To an Emrys Optimizer 2-5 mL pyrex reaction vessel Ni/C (67.3 mg, 0.04 mmol) was added under argon at room temperature. Tetrahydrofuran (1 mL) was added followed by n-BuLi (31 pL, 2.55 M in hexanes, 0.08 mmol). 

The condensation reactions used either one ketone or a mixture of two ketones (a total of 10 separate reactions). A dry zinc dust melt caused the condensation (10). A mixture of ketone, zinc dust (J. T. Baker), sodium chloride (Leslie Salt), and zinc chloride (Mallinckrodt) (1 1 1 5 by weight, respectively) was ground, thoroughly mixed, and placed in a 50-mL flat-bottomed borosilicate glass (Pyrex) reaction vessel. 

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