Chlorination process

Propylene oxide [75-56-9] is manufactured by either the chlorohydrin process or the peroxidation (coproduct) process. In the chlorohydrin process, chlorine, propylene, and water are combined to make propylene chlorohydrin, which then reacts with inorganic base to yield the oxide. The peroxidation process converts either isobutane or ethylbenzene direcdy to an alkyl hydroperoxide which then reacts with propylene to make propylene oxide, and /-butyl alcohol or methylbenzyl alcohol, respectively. Table 1 Hsts producers of propylene glycols in the United States. 

In the general process, chlorine dioxide gas is absorbed into a cooled (15—20°C) circulating solution containing sodium hydroxide and hydrogen peroxide. The predominant reaction is (141,142) ... 

Refractory metals Zirconium Hafnium Titanium Kroll process, chlorination, and magnesium reduction Chlorine, chlorides, SiCli Wet scrubbers... 

One of the concerns that exists in thermally processing chlorinated organics is that the by-products of combustion that are formed may be more harmful than the initial... 

There are three basic terms used in the chlorination process chlorine demand, chlorine dosage and chlorine residual. Chlorine demand is the amount of chlorine which will reduced or consumed in the process of oxidizing impurities in the water. Chlorine dosage is the amount of chlorine fed into the water. Chlorine residual is the amount of chlorine still remaining in water after oxidation takes place. For example, if a water has 2.0 ppm chlorine demand and is fed into the water in a chlorine dosage of 5.0 ppm, the chlorine residual would be 3.0 ppm. 

In chlorinations either a substitution or an addition process can occur with the ultimate reaction pathway(s) determined by a combination of factors, which include the reaction conditions, the positions and natures of any substituents present, and the catalyst used. Uncatalyzed chlorination of benzothiadiazole is an exothermic reaction that gives rise to a mixture of isomeric tetrachloro addition products. These are converted in basic medium into 4,7-dichloro-2,1,3-benzothiadiazole (70RCR923). When an iron(III) catalyst is present 4- and 7-chloro substitution becomes the dominant process. Chlorination of a number of 4-substituted 2,1,3-benzothiadiazoles (43) using an oxidative process gave a combination of chlorinated and oxidized products. The 4-hydroxy, 4-amino-, 4-methyl-amino, and 4-acetoxy derivatives of 43 all formed the chloroquinones (44) (40-61% yields). With the 4-aIkoxy substrates both 44 and some 5,7-dichlorinated product were obtained (88CHE96). 

Another important factor to be considered is the effect of temperature in the washing process. Chlorine has its maximum solubility at 4 °C, but it has been shown that the chlorinated washing water should ideally have a temperature that is at least 10 °C higher than that of the product. Results from a study by Zhuang et al. (1995) showed that a significantly higher number of Salmonella cells was taken up by the core tissue when tomatoes at a temperature of 25 °C were dipped in a chlorine solution held at 10 °C. 

BMS A process for removing mercury from the effluent from the Castner-Kellner process. Chlorine is used to oxidize metallic mercury to the mercuric ion, and this is then adsorbed on activated carbon impregnated with proprietary sulfur compounds. Developed by Billingsfors Bruks, Sweden. 

These protocols were applied to pyridines, quinolines, and naphthyridines. They are compatible with other functional groups, for instance, acid derivatives. Dehydration can be effected by a chemical process (chlorinating agents), or simply by heating. Method A3 generally required harsh conditions, since in most examples no base was added for HC1 consumption, therefore lowering the reactivity of the pyridine nitrogen, present as its hydrochloride salt. 

Thus, by the operation of the process, chlorine is produced in the end compartments, and caustic soda and hydrogen in the centre one. 

This process seems much simpler than the Ziegler process, and you may wonder why it has not crowded Ziegler out. The problem is the olefin feed. Where do you get a ready supply of olefins the right size to feed to the process The answer is you have to malce them, and therein lies the rub. Normal paraffins from petroleum waxes or other chemical processes provide the feedstock to a two-step process, chlorination and dehydrochlorination, which produces an olefin corresponding to the paraffin. 

Nomad Press is committed to preserving ancient forests and natural resources. We elected to Amazing Kitchen Chemistry Projects on 30% postconsumer recycled paper, processed chlorine free. As a result, for this printing, we have saved ... 

Table 5-1 lists the facilities in each state that manufacture or process chlorine dioxide, the intended use, and the range of maximum amounts of chlorine dioxide that are stored on-site. There are 107 facilities that produce or process chlorine dioxide in the United States. Current estimates for the amounts of chlorine dioxide stored on-site as a by-product or impurity range from 99 to 9,999,999 pounds/year (45-4,539,510 kg/year) (TRIOO 2002). The data from the Toxics Release Inventory (TRI) listed in... 

The base-catalyzed decomposition (BCD) technology is a chemical dechlorination technology for the ex situ treatment of soils, sludges, and liquids contaminated with PCBs and other chlorinated compounds. In the two-step process, chlorine atoms on chlorinated molecules are removed and replaced by hydrogen atoms, using heat and commonly available chemicals in the presence of a catalyst. 

Figure 19-3 shows an electrolj ic cell using molten sodium chloride. A redox reaction between sodium and chlorine won t happen spontaneously, but the electrical energy produced by the battery provides the additional energy needed to fuel the reaction. In the process, chlorine anions cire oxidized at the anode, creating chlorine gas, and sodium is reduced at the cathode and is deposited onto it as sodium metal. 

Side-Chain Chlorination of Toluene. Benzyl chloride, used mainly in the manufacture of plasticizers, may be prepared by the thermal or photochemical chlorination of toluene.191,192 In the thermal process chlorine is passed through toluene at 65-100°C. To minimize the formation of benzal chloride and benzotrichloride, the conversion is limited to about 50%. Since the density of the reaction mixture increases linearly with the formation of benzyl chloride,145 measurement of density is used to monitor the progress of the reaction. The overall yield based on toluene is about 90%, and the maximum conversion to benzyl chloride is above 70%. Higher yields in photochemical chlorination may be achieved. 

In the mercury cell process chlorine is liberated from a brine solution at Ihe anodes which are. today, typically melal anodes (Dimensionally Stable Anodes or DSAl. Collection and processing of the chlorine is similar lo Ihe techniques employed when diaphragm cells are used. However. Ihe cathode is a flowing bed or mercury. When sodium is released by electrolysis it is immediately amalgamated with the mercury The inereury amalgam is then decomposed in a separate cell 10 form sodium hydroxide and Ihe mercury is returned for reuse. 

A quantum chemistry study of the reaction of chloroprene with CI2 has revealed two transition states for substitutive chlorination, which is consistent with two consecutive processes chlorination to give a carbocation followed by abstraction of the originally allylic proton. On the other hand, a single transition state was observed for additive chlorination. The potential barriers for the former process lay below that for the latter102. 

In the process, chlorine is fed in below the surface of the aluminum, and the product sublimes and is collected by condensing. These air-cooled condensers are thin-walled, vertical steel cylinders with conical bottoms. Aluminum chloride crystals form on the condenser walls and are periodically removed, crushed, screened, and packaged in steel containers. 

As chlorine may affect the catalytic behavior of rhodium, it is important to know how residual chlorine from the preparation is affected by the reduction process. Chlorine contents down to about 1% are easily determined by XPS, but in order to detect lower concentrations then SIMS is the best choice. 

We used the radical relay process, chlorinating C-9 and then generating the 9(11) double bond, in a synthesis of cortisone 91 [158]. This is a substitute for manufacturing processes in which C-9 or C-ll are hydroxylated by biological fermentation. Also, with templates that directed the chlorination to C-17 of 3a-cholestanol, such as that in 90, we were able to remove the steroid sidechain [159-162]. Using an electrochemical oxidation process, we could direct chlorination by simple chloride ion with an iodo-phenyl template [163]. A general review of the processes with iodophenyl templates has been published [164]. 

In the Columbia process chlorine diluted with air and carbon dioxide is passed through solid sodium carbonate or bicarbonate. In the reaction chlorine monoxide is formed according to the equation ... 

Summary Bleach can be made using an electrochemical process whereby pickling salt is electrolyzed. During the process, chlorine gas is evolved at the anode, and sodium hydroxide is liberated at the cathode. As the process proceeds, the chlorine reacts with the sodium hydroxide forming sodium hypochlorite (bleach). Some chlorine gas does escape, so use proper ventilation when carrying out this operation. 

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