Quartz irradiation

Fig. 10. Ge(Li) gamma-ray spectrum for a thermal neutron irradiated tektite. A major portion of the la4Sb activity in this spectrum is due to antimony contamination in the quartz irradiation vial...

Fig. 1 Irradiation setup for pulse radiolysis consisting of a solution reservoir, a peristaltic pump, and a quartz irradiation cell. Prior and during irradiation, the polymer solution is continuously saturated with argon...

A solution of anisole and cyclopentene in cyclohexane (2 M in each solute) was introduced into a cylindrical quartz irradiation tube. The tube was placed in a Rayonet PRP-208 reactor equipped with four 253.7 nm lamps (Hg), and sealed with a rubber serum cap to allow removal of sample with a syringe. The part of the tube void of solution was covered with aluminum foil to prevent reactions in the gas phase. The irradiation was continued without degassing until product formation (as monitored by GC) slowed down to a negligible rate. After irradiation, the solution was transferred to a round-bottom flask and the volatile materials removed at reduced pressure while heating on a water bath (< 80 °C). The residue was distilled bulb-to-bulb using a Nj trap to separate the adduct from polymeric material. Only the e/jrfo-isomer was thus obtained yield 85%. 

Especially for the synthesis of nanogels (e.g. by intramolecular cross-linking of polymer molecules with high molecular weights), the method of pulse irradiation is useful, see Fig. 10. The polymer is dissolved and the solution, flowing through a quartz irradiation cell (effective volume about 1 ml), is pulse-irradiated with electrons of several MeV (in our experiments 6 MeV) generated by a linear accelerator (ELU-6, Eksma, Russia). Pulse frequency of 5.0 Hz and pulse duration of 3 ps were applied at a flow rate of 5.0 ml/s. 

The apparatus consists of a xenon flash lamp, a mercury ultraviolet lamp, a Suprasil quartz irradiation cell, a tungsten lamp, optical system, red filters, photomultiplier, and an oscilloscope. A block diagram of the apparatus is shown in Figure 1. 

Add about 105 ml of sample to a quartz irradiation tube after first rinsing the tube with a little sample. Add 1-2 drops of hydrogen peroxide, mix, and irradiate for 1-1.5 hr (Note a). Cool the tube and contents to room temperature. 

A solution of 7-bromo-2-(fV-methylanilino)hept-2-enenitrile (145 mg, 0.52 mmol) in cyclohexane (60 ml) was placed in a quartz tube and purged with oxygen. The sample was irradiated for 8h in a Rayonet Model RPR-100 Reactor using 254 nm light. An oxygen atmosphere was maintained during... 

Quartz. When colorless, quart2 [14808-60-7] is also known as rock crystal. When irradiated, it becomes smoky from a color center associated with a ubiquitous Al impurity at about the 0.01% level. The name citrine [14832-92-9] is used when quart2 is colored by Fe, and irradiation of this can produce the purple-colored amethyst [14832-91-8] under certain circumstances (2). Although not signiftcandy lower priced than the natural materials, synthetic citrine and amethyst ate used in jewelry because of the abiUty to provide matched sets of stones from large, up to 7-kg, hydrothermaHy grown crystals. 

Color Changes in Quartz. AH quart2 contains small amounts of substitutional Al, typically 0.01%, as well as similar amounts of interstitial hydrogen or alkah metal ions. When an Al " replaces a one positive charge is missing and electroneutraUty is maintained by or Na", etc. Irradiation ejects one of a pair of electrons on an O adjacent to an Al ... 

A -Bridgehead compounds have been obtained from the photochemical cyclization of cfi-1-styrylimidazoles. For example, irradiation of the imidazole (532) in methanol in the presence of I2 resulted in cyclization at the 2-position of the imidazole ring with the formation of an imidazo[2,l-a]isoquinoline (533) (76JCS(Pl)75). Isomerization of the trans-to the c/i-styrylimidazole was followed by photodehydrocyclization, trans- 1-Styrylbenzimidazole (534) was isomerized under Pyrex-filtered light in the presence of one molar equivalent of I2. The resulting cis isomer on irradiation through quartz gave the benzimidazo[2,l-a]isoquinoline (535) in 53% yield. 

Size requirements are limited by packaging considerations for neutron irradiation. Typically, polyethylene or quartz containers are used to contain the sample in the reactor core. For example. Si wafers are cleaved into smaller pieces and dame sealed... 

The photochemical addition of trifiuoroiodomethane to unsaturated systems has been thoroughly investigated by Haszeldine. Little use has been made of this reaction in the steroid field. Irradiation of the enol ether (64) in trifiuoroiodomethane containing pyridine in a quartz vessel furnishes in 60 %... 

A solution of 500 mg 3 -acetoxypregn-5-en-20-one-[17a,16a-c]-A -pyrazoline in 100 ml of anhydrous dioxane is stirred with a magnetic stirrer and irradiated in a water-cooled quartz reactor with a high pressure Biosol Philips 250 W quartz lamp for 1 hr. The solvent is removed at reduced pressure and the residue is chromatographed on alumina (activity III). Elution with petroleum ether-benzene (3 1) gives 0.2 g (42%) of 3 -acetoxy-16a,17a-methylene-pregn-5-en-20-one mp 193-193.5° after two recrystallizations from methylene dichloride-ethyl acetate. 

Note 7. The irradiation is performed in a cylindrical container with a central water cooled quartz finger and an 80 Watt Hg-Hochdruckbrenner Q 81 (Quarzlampen G.m.b.H., Hanau). 

A solution of 0.17 g (51) in 160 ml benzene is stirred magnetically and irradiated for 6 hr with a Hanau NK 6/20 low-pressure mercury lamp (main emission at 2537 A) placed in a central water-cooled quartz tube. Cyrstalliza-tion of the crude product gives 0.15 g (52) (88%). 

With 2537 k-Light. 1 g (140) in 140 ml anhydrous dioxane is irradiated for 20 hr at room temperature with a Hanau NK 6/20 low-pressure mercury lamp placed in a central water-cooled quartz finger. 0.19 g of (141) crystallize from the crude reaction mixture as described above. Chromatography of the residual material on silica gel with benzene-ethyl acetate (4 1) gives 0.29 g of B-nortestosterone acetate [(142) 28.5 %] and starting material (140). 

Benzylenol ethers rearrange in an apparently similar fashion via photolytic fission of the benzyl-oxygen bond and subsequent recombination steps. Irradiation in quartz of a cyclohexane solution of 3-benzyloxycholesta-3,5-diene (250) leads to 23% (251), 13% (252) [presumably formed from (251) during workup] and 10% (253). ... 

Acridine-9-carbonitrile 10-oxide (la 3.00g, 13.6 mmol) in benzene (1.8 L) in a quartz immersion well was irradiated for 3 h with a Hanovia high-pressure 450-W Hg lamp equipped with a Pyrex filter. The resulting solution was evaporated under reduced pressure and the residue was extracted with pentane (3 x 50 mL). The combined extracts were evaporated under reduced pressure at 20 C to give orange crystals yield 1.8 g (60%) mp 105-109 C (Et20/pentane). 

Phenyl-2-oxa-3-azabicyclo[3.2.0]hepta-3,6-diene (11 0.200 g, 1.17 mmol) in hexane was irradiated in a quartz vessel using a Rayonet photoreactor to give the product as a yellow oil yield 0.160 g (SO %). The compound can be distilled below 100 C at 10 4Torr. It gradually resinifies when kept in air at 20 C. 

It is prepd by heating a mixt of N trifluoride, Sb pentafluoride, and F in a Monel tube reactor at 200° for 2.5 days (Ref 1) or by irradiating the same reagents with UV radiation in a quartz bulb (Ref 9) ... 

While still slightly warm from the drying oven, the photolysis vessel with a water-jacketed quartz immersion well (Note 1) (section A of Figure 2) is charged with 500 ml. of anhydrous tetrahydrofuran (Note 2) and 10 ml. (8.05 g., 0.122 mole) of cyclopentadiene (Note 3). The solution is cooled in an ice bath and purged with dry nitrogen for 2 minutes. Then the vessel is sealed, the lamp inserted, and the solution irradiated at 0° for 30 minutes. During this period, sections B and C... 

Considering the formation of saturated five-membered heterocycles with two heteroatoms, it is worth to note the possibility to prepare 1,3-dioxolanes, dithiane, oxathianes 148 [93] and dioxolanones 149 [94] by condensation of the corresponding carbonyl compounds under microwave irradiation in acid medium (Scheme 52). The reaction, which is very useful for the protection of carbonyl compounds or for the preparation of useful synthetic intermediates, has also been carried out under batch conditions over Montmorillonite KIO clay in more than 150 g scale, using a 1 L quartz reactor [95]. 

Benzene, benzene-t/i, CFCI3 and CF3CCI3 were obtained commercially and were not further purified. Solutions of c a 0.3 - 1 volume % of benzene in CFCI3 were prepared in suprasil quartz tubes of 4 mm outer diameter on a vacuum line. The samples were degassed and sealed under vacuum (< 10-4 -porr). Polycrystalline samples were prepared by rapid freezing in liquid nitrogen. The samples were irradiated at 77 K for 5 minutes at an approximate dose rate of 250 G/min. using the radiation from an X-ray tube with a W anode operated at 70 kV and 20 mA. 

UV irradiation of this bacterial cells using a broadband mercury-quartz lamp through an interference filter (bandwith 254 nm), provided preferential DNA damage with minimal effects on other subcellular structures. The exposure time ranged from 0 to 180 minutes in increments of 60 minutes, which gave total dose of UV exposure 1.21, 2.43 and 3.64 J/ m. ... 

The apparatus is dried in an oven at 140° overnight and cooled under nitrogen or argon prior to the irradiation. A Vycor filter sleeve and a 450-watt medium-pressure mercury lamp are placed in the immersion well. The Vycor filter, the quartz immersion well (catlog No. 19434), the 450-watt mercury lamp (catalog No. 679A36), and the requisite transformer are all available from Hanovia Lamp Division, Canrad-Hanovia Inc., 100 Chestnut Street, Newark, New Jersey 07105. 

C. tert-Butyl fi-(l-ethoxycyclopropyl)carbamate. A three-necked, cylindrical irradiation vessel is equipped with a magnetic stirring bar, a water-jacketed quartz immersion well, an inert gas inlet,... 

It seems that deep-seated cleavage of the dioxin nucleus must accompany dechlorination in methanol. When pure dibenzo-p-dioxin (II) was irradiated in cyclohexane solution in a quartz cuvette, it darkened in color, and a precipitate of intractable dark brown material was collected and was insoluble in the common solvents except for methanol. 

Besides thermolysis, the photochemical decomposition of solid trihalo-methylmercury compounds RHgCCli, CF3HgOCOCF3 and Hg(OCOCF3)2 has been studied (Scheme 2). The irradiation of samples placed in an evacuated quartz tube, which was connected to a helium cryostat, was carried out at -50 to +10°C. Thus, a desorption into the gas phase of the primary products of the photolysis occurred, and consequent low-temperature matrix stabilization of them was made. As a result, the formation of only the radicals CCI3 (1 3 898 cm" ) and CF3 (vi 1084, V2 702, P2+ V4 1205, r>3 1249 cm ) or of products of their secondary reactions was observed (Mal tsev et al., 1974, 1975, 1977b). 

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