Vessels irradiation

Two recent examples of Diels-Alder cydoadditions performed by microwave dielectric heating are described in Scheme 11.3. In both reactions diene and dien-ophile were employed neat, i.e. without the addition of solvent. The reaction described by Trost and Crawley between compounds 7 and 8 (irradiation for 20 min at 165 °C or for 60 min at 150 °C) produced the cycloadduct 9 in nearly quantitative yield [42]. In the process reported by de la Hoz et al., open-vessel irradiation of 3-(2-arylethenyl)chromones 10 with maleimides 11 at 160-200 °C for 30 min furnished tetracyclic adducts of type 12 with minor amounts of other diastereoisomers [43]. 

Integral reactor layout, minimization of through-vessel penetrations and their location at the upper part of the reactor vessel, large coolant volume (up to 150 m ) above the core, and low reactor vessel irradiation (fluence 5. 10 n/cm ). 

EVANS, J.C., et al., Long-Lived Activation Products in Light-Water Reactor Construction Materials Implications for Decommissioning, Radioactive Waste Management and the Nuclear Fuel Cycle 1988, Vol. 11(1), pp. 1-39. WASASTJERNA, F., User s Manual for REPVICS (Reactor Pressure Vessel Irradiation Calculation System), Technical Research Centre of Finland, Nuclear Engineering Laboratory, Technical Report REP-16/83 (1983). 

In 1959, an American Society for Testing and Materials task group made recommendations on test procedures for evaluating radiation effects on materials, which led to recommended practices for surveillance tests on structural materials in nuclear reactors. As part of their safety analysis review, the AEG ensured that each plant conducted a reactor vessel irradiation surveillance program per American Society for Testing and Materials standards to evaluate the shift in RTnot over the plant life, especially in the beltline region opposite the core midplane where the reactor vessel sees the largest neutron flux. 

Equilibrium geometry calculated using PM3 (PC Spartan Pro). Reactions conducted at 0.4 g/1 enediyne in 2-propanol in a quartz vessel, irradiated using a 450 W (Hanovia) lamp. 

Radiation-Density Gauges Gamma radiation may be used to measure the density of material inside a pipe or process vessel. The equipment is basically the same as for level measurement, except that here the pipe or vessel must be filled over the effective, irradiated sample volume. The source is mounted on one side of the pipe or vessel and the detector on the other side with appropriate safety radiation shielding surrounding the installation. Cesium 137 is used as the radi-... 

Mager, T. R. and Marschall, C. W. 1984 Development of Crack Arrest Data Bank Irradiated Reactor Vessel Steels. 2, EPRI NP-3616, Palo Alto, CA, July. 

The HFBR at Brookhaven National Laboratory is a heavy water moderated and cooled reactor designed to provide an intense beam of neutrons to the experimental area. In addition using thimbles i oiitaincd within the vessel, it provides isotopic production, neutron activation analysis, ami muiemi irradiations. It began operation in 1965 at a power of 40 MW to be upgraded to 60 MW m 19S2. 

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 %... 

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. 

Phenylquinoline 1-oxide (10.0 g, 45.2 mmol) in acetone (1.25 L) was irradiated for 12 h with a Hanovia Q-700 medium-pressure Hg lamp, equipped with a Pyrex cooling mantle placed in the center of the reaction vessel, when TLC showed the absence of starting material. The solution was evaporated in vacuo and the residue was extracted with boiling hexane. The extract was evaporated under reduced pressure and the residue was crystallized (pentane) yield 9.0 g (90%) mp 65-66 C. 

A solution of quinoline 1-oxide (0.29 g, 2 mmol) in cyclohexane (1 L) was dehydrated by azeotropic distillation in the reaction vessel. The solution was purged with dry N2 and irradiated with a Hanau high-pressure Hg lamp. The resulting solution was evaporated and the residue was extracted with a little cyclohexane. The insoluble part contained carbostyril (3). The cyclohexane extract was evaporated and the residue purified by short-path distillation at 50°C/0.1 Torr yield 0.174g (60%) moisture-sensitive oil. 

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... 

Our experimental techniques have been described extensively in earlier papers (2, 13). The gamma ray irradiations were carried out in a 50,000-curie source located at the bottom of a pool. The photoionization experiments were carried out by krypton and argon resonance lamps of high purity. The krypton resonance lamp was provided with a CaF2 window which transmits only the 1236 A. (10 e.v.) line while the radiation from the argon resonance lamp passed through a thin ( 0.3 mm.) LiF window. In the latter case, the resonance lines at 1067 and 1048 A. are transmitted. The intensity of 1048-A. line was about 75% of that of the 1067-A. line. The number of ions produced in both the radiolysis and photoionization experiments was determined by measuring the saturation current across two electrodes. In the radiolysis, the outer wall of a cylindrical stainless steel reaction vessel served as a cathode while a centrally located rod was used as anode. The photoionization apparatus was provided with two parallel plate nickel electrodes which were located at equal distances from the window of the resonance lamp. 

Irradiation Procedure. Reaction mixtures were prepared at room temperature by transferring desired quantities of reactants from their storage bulbs to the reaction vessel, a 500-cc. spherical borosilicate glass flask attached to the vacuum line by a section of glass capillary tubing and a 4-mm. bore threaded glass valve with a Teflon plug (Fischer and Porter 795-609). Prior to each experiment this vessel was baked under vacuum at 500°C. for 12 or more hours. 

Benzothiazepines belong to the three classes of calcium channel blockers which are important cardiovascular drugs in the management of angina pectoris and hypertension. A diastereoselective one-pot synthesis of the trans-and ds-3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-l,5-benzothiazepin-4-one nucleus, a key intermediate in the preparation of the calcium channel blocker Diltiazem, was carried out under microwave irradiation in an open vessel (Scheme 25). Control of the diastereoselectivity was achieved by vary-... 

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