Compound pressure vessels

Sulfurization of unsaturated compounds and meicaptans is normally carried out at atmospheric pressure, in a mild or stainless steel, batch-reaction vessel equipped with an overhead condenser, nitrogen atmosphere, an agitator, heating media capable of 120—215°C temperatures and a scmbber (typically caustic bleach or diethanolamine) capable of handling hydrogen sulfide. If the reaction iavolves the use of H2S as a reactant or the olefin or mercaptan is a low boiling material, a stainless steel pressurized vessel is recommended. 

Sulfurchlorination of unsaturated compounds or mercaptans is normally carried out at atmospheric pressure in a glass-lined reaction vessel because of the potential to Hberate HCl during the reaction. The sulfurchlorination vessel is equipped with a cooling jacket or coils (very exothermic reaction), a nitrogen or dry air sparging system, an overhead condenser, and a caustic or bleach scmbber. If one of the reactants (olefin or mercaptan) is alow boiling material, ie, isobutylene, a glass-lined pressure vessel is recommended. 

HGSystem offers the most rigorous treatments of HF source-term and dispersion analysis a ailable for a public domain code. It provides modeling capabilities to other chemical species with complex thermodynamic behavior. It treats aerosols and multi-component mixtures, spillage of a liquid non-reactive compound from a pressurized vessel, efficient simulations of time-dependent... 

Most static-bomb calorimeters used are of the isoperibol type, such as the one in figure 7.1. Here, the bomb A is a pressure vessel of 300 cm3 internal volume. Combustion bombs are usually made of stainless steel and frequently have an internal platinum lining to prevent corrosion. In a typical high-precision experiment, the platinum ignition wire B connects the two electrodes C, which are affixed to the bomb head. A cotton thread fuse D (other materials such as polyethene are also used), of known energy of combustion, is weighed to a precision of 10-5 — 10-6 g and tied to the platinum wire. A pellet E of the compound... 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

Fixed-Roof Tanks. The effect of internal pressure on plate structures, including tanks and pressure vessels, is important to tank design. If a flat plate is subjected to pressure on one side, it must be made quite thick to resist bending or deformation. A shallow cone-roof deck on a tank approximates a flat surface and is typically built of 3/ 16-in. (4.76-mm) thick steel (Fig. 4a). This is unable to withstand more than a few inches of water column pressure. The larger the tank, the more severe the effect of pressure on the structure. As pressure increases, the practicality of fabrication practice and costs force the tank builder to use shapes more suitable for internal pressure. The cylinder is an economic and easily fabricated shape for pressure containment. Indeed, almost all large tanks are cylindrical. The problem, however, is that the ends must be closed. The relatively flat roofs and bottoms or closures of tanks do not lend themselves to much internal pressure. As internal pressure increases, tank builders use roof domes or spheres. The spherical tank is the most economic shape for internal pressure storage in terms of required thickness, but it is generally more difficult to fabricate than a dome- or umbrella-roof tank because of its compound curvature. 

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Our initial foray into microwave chemistry was with a reaction that had proven inaccessible using traditional thermal techniques. The reaction was a simple [3 + 2] cycloaddition reaction between a di-substituted maleimide and a simple azomethine ylide generated in situ (Scheme 8.1)13. The reaction with the unsubstituted maleimide had yielded excellent results for a variety of dipoles however, even simple methyl substitution had dramatic reductions in product yield (Table 8.1). The interest in our group was in generating novel three-dimensional scaffolds for library generation and the di-substituted maleimides would be a key entry point into these compounds, so the need for the products had us attempt these reactions in sealed pressure vessels. While we were pleased to obtain some of the desired product, the extremely low yield had eliminated this class of compounds from consideration. 

After reviewing the literature, the scientist set out on optimization of the first key step, a SnAt reaction. Typical SnAt reaction conditions were initially attempted, examples of which can be seen in Table 8.4. Typical reflux heating in solvents such as DMF and DMSO provided poor yields of the desired products even after prolonged heating. Only with the use of a pressurized vessel were the satisfactory levels of the desired product obtained. However, it should be pointed out that under typical library production conditions, sealed tubes could not be used to produce the desired compounds, and in all actuality the use of refluxing DMSO would also be problematic. After examining... 

If the alcoholysis of the foregoing p-bromobenzenesulfonate esters is carried out with higher alcohols under reflux or with any alcohol in a pressure vessel at temperatures above 120°, partial isomerization at carbon atom 3 takes place, and mixtures of 3-normal- and 3-iso- 18-epi ethers are obtained. Of special interest is the alcoholysis effected with glycol monomethyl ether where separation of the mixture proved to be possible, as it is in many other cases. The 18-epi compound (XXXII) was antihypertensive, whereas the 3-iso-18-epi ether (XXXIII) had a stimulant activity. This was actually the first compound from any of the 3-iso series possessing any pharmacological activity. 

Isolation of Processes To minimize cross-contamination and microbiological contamination, the manufacturer may develop special procedures for the isolation of processes. The level of facilities isolation depends on the types of products to be manufactured. For instance, steroids and sulfas require more isolation than over-the-counter (OTC) oral products [6], To minimize exposure of personnel to drug aerosols and loss of product, a sealed pressure vessel must be used to compound aerosol suspensions and emulsions [21], An example of cross-contamination with steroids was the controversial case of a topical drug manufactured for the treatment of skin diseases. Fligh-performance liquid chromatography/ultraviolet and mass spectrometry (FIPLC/UV, FIPLC/MS) techniques were used by the FDA for the detection of clobetasol propionate, a class 1 superpotent steroid, as an undeclared steroid in zinc pyrithione formulations. The product was forbidden and a warning was widely published [22],... 

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