Cooling reactive

In a more recent study [15], Westerterp and Molga introduced a set of dimensionless numbers (cooling, reactivity, and exothermicity numbers) characterizing the stability of heterogeneous slow liquid-liquid reactions in the semi-batch reactor. They demonstrated that the key parameter is the cooling number Co ... 

The reactivity of size-selected transition-metal cluster ions has been studied witli various types of mass spectrometric teclmiques [1 ]. Fourier-transfonn ion cyclotron resonance (FT-ICR) is a particularly powerful teclmique in which a cluster ion can be stored and cooled before experimentation. Thus, multiple reaction steps can be followed in FT-ICR, in addition to its high sensitivity and mass resolution. Many chemical reaction studies of transition-metal clusters witli simple reactants and hydrocarbons have been carried out using FT-ICR [49, 58]. 

Some less reactive tertiary amines can be mixed with an excess of methyl toluene-/)-sulphonate, m.p. 28 , and the mixture (without a solvent) heated to a much higher temperature. The mixture is allowed to cool, but before solidification occurs, it is thoroughly stirred with ether to extract unused sulphonate, and the insoluble quaternary metho-toluene-/)-sulphonate may then crystallise. If ciystallisation does not occur, dissolve this residue in ethanol and treat one portion with ethanolic picric acid (to precipitate the methopicrate) and another portion with cold concentrated ethanolic sodium iodide (to precipitate the methiodide). (M.ps. of the siilphon.ates, pp. 553 -554.)... 

Some industrial processes produce predorninately latent air conditioning loads. Others dictate very low humidities and when the dew point falls below 0°C, free2ing becomes a major concern. Dehydration equipment, using soHd sorbents such as siUca gel and activated alurnina, or Hquid sorbents such as lithium chloride brine and triethylene glycol, may be used. The process is exothermic and may require cooling the exiting air stream to meet space requirements. Heat is also required for reactivation of the sorbent material. 

Cooling is routinely appHed, either with ambient process water if THF is the solvent or with chilled brine if diethyl ether is used. Since Grignard reagents are particularly reactive with water, Hquid hydrocarbon coolants may be preferred, to eliminate the risk that could arise from a cooling-system leak. 

The next step is to apply a number of loss control credit factors such as process control (emergency power, cooling, explosion control, emergency shutdown, computer control, inert gas, operating procedures, reactive chemical reviews), material isolation (remote control valves, blowdown, drainage, interlocks) and fire protection (leak detection, buried tanks, fire water supply, sprinkler systems, water curtains, foam, cable protection). The credit factors are combined and appHed to the fire and explosion index value to result in a net index. 

Steam generation. The char (product) is cooled by circulation of product gas. The char reactivity increases with time and must be stored carefully. 

Thermal Process. In the manufacture of phosphoric acid from elemental phosphoms, white (yellow) phosphoms is burned in excess air, the resulting phosphoms pentoxide is hydrated, heats of combustion and hydration are removed, and the phosphoric acid mist collected. Within limits, the concentration of the product acid is controlled by the quantity of water added and the cooling capabiUties. Various process schemes deal with the problems of high combustion-zone temperatures, the reactivity of hot phosphoms pentoxide, the corrosive nature of hot phosphoric acid, and the difficulty of collecting fine phosphoric acid mist. The principal process types (Fig. 3) include the wetted-waH, water-cooled, or air-cooled combustion chamber, depending on the method used to protect the combustion chamber wall. 

Flame retardants (qv) are incorporated into the formulations in amounts necessary to satisfy existing requirements. Reactive-type diols, such as A/ A/-bis(2-hydroxyethyl)aminomethylphosphonate (Fyrol 6), are preferred, but nonreactive phosphates (Fyrol CEF, Fyrol PCF) are also used. Often, the necessary results are achieved using mineral fillers, such as alumina trihydrate or melamine. Melamine melts away from the flame and forms both a nonflammable gaseous environment and a molten barrier that helps to isolate the combustible polyurethane foam from the flame. Alumina trihydrate releases water of hydration to cool the flame, forming a noncombustible inorganic protective char at the flame front. Flame-resistant upholstery fabric or liners are also used (27). 

Reactivity. Bromine is nonflammable but may ignite combustibles, such as dry grass, on contact. Handling bromine in a wet atmosphere, extreme heat, and temperatures low enough to cause bromine to soHdify (—6° C) should be avoided. Bromine should be stored in a cool, dry area away from heat. Materials that should not be permitted to contact bromine include combustibles, Hquid ammonia, aluminum, titanium, mercury, sodium, potassium, and magnesium. Bromine attacks some forms of plastics, mbber, and coatings (62). 

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