Chlorinated additives

Chlorinated Additive Flame Retardants. Table 7 is a general listing of chlotinated compounds used as additive flame retardants. 

Chlorine Addition. Chlorine addition and some chlorine substitution occurs at normal or slightly elevated temperatures in the absence of catalysts. The chlorination of molten naphthalene under such conditions yields a mixture of naphthalene tetrachlorides, a monochloronaphthalene tetrachloride, and a dichloronaphthalene tetrachloride, as well as mono- and dichloronaphthalenes (35). Sunlight or uv radiation initiates the addition reaction of chlorine and naphthalene resulting in the production of the di- and tetrachlorides (36). These addition products are relatively unstable and, at ca 40—50°C, they decompose to form the mono- and dichloronaphthalenes. 

Direct Chlorination of Ethylene. Direct chlorination of ethylene is generally conducted in Hquid EDC in a bubble column reactor. Ethylene and chlorine dissolve in the Hquid phase and combine in a homogeneous catalytic reaction to form EDC. Under typical process conditions, the reaction rate is controlled by mass transfer, with absorption of ethylene as the limiting factor (77). Ferric chloride is a highly selective and efficient catalyst for this reaction, and is widely used commercially (78). Ferric chloride and sodium chloride [7647-14-5] mixtures have also been utilized for the catalyst (79), as have tetrachloroferrate compounds, eg, ammonium tetrachloroferrate [24411-12-9] NH FeCl (80). The reaction most likely proceeds through an electrophilic addition mechanism, in which the catalyst first polarizes chlorine, as shown in equation 5. The polarized chlorine molecule then acts as an electrophilic reagent to attack the double bond of ethylene, thereby faciHtating chlorine addition (eq. 6) ... 

With aluminum sulfate, optimum coagulation efficiency and minimum floe solubiUty normally occur at pH 6.0—7.0. Iron coagulants can be used successfully over the much broader pH range of 5.0—11.0. If ferrous compounds are used, oxidation to ferric iron is needed for complete precipitation. This may require either chlorine addition or pH adjustment. 

The dkect high temperature chlorination of propylene continues to be the primary route for the commercial production of aHyl chloride. The reaction results in aHyl chloride selectivities of 75—80% from propylene and about 75% from chlorine. Additionally, a significant by-product of this reaction, 1,3-dichloropropene, finds commercial use as an effective nematocide when used in soil fumigation. Overall efficiency of propylene and chlorine use thus is significantly increased. Remaining by-products include 1,2-dichloropropane, 2-chloropropene, and 2-chloropropane. 

The piincipal by-pioducts aie the result of direct chlorine addition to give 1,2-dichlotoptopane [78-87-5] and ether formation. The ether product is dichloropropyl ether [108-60-1] or 2,2 -oxybis(l-chloropropane). 

These values assume chlorination in carbon tetrachloride solution under homogeneous conditions favoring random distribution of chlorine atoms along the chain. Viscous reaction conditions, faster chlorine addition rates, lower temperature conditions, etc, can lead to higher AH at equivalent chlorine levels because of more blocky chlorine distribution on the polymer chain. 

D. 3,3-Diahlarothietane 1,1-dioxide. Thietane 1,1-dioxide (5.0 g, 0.047 mol) Is placed In a 500-mL, three-necked, round-bottomed flask equipped with a reflux condenser, magnetic stirrer, and chlorine gas bubbler. Carbon tetrachloride (350 mL) Is added and the solution Is irradiated with a 250-watt sunlamp (Note 5) while chlorine Is bubbled through the stirred mixture for 1 hr (Note 9). Irradiation and chlorine addition are stopped and the reaction mixture is allowed to cool to room temperature. The product Is collected by filtration as a white solid (4.0-4.4 g, 49-53%), mp 156-158°C (Note 10). The product can be used without further purification or It can be recrystallized from chloroform. 

The control of the reaction was based on the assumption that stopping the flow of chlorine would stop all reaction this was true on the pilot unit but not on the full-scale plant. On the pilot unit, there was no stirrer, as the incoming chlorine gave sufficient mixing. When chlorine addition stopped, mixing also stopped and so did the reaction. On the full-scale plant, a stiirer was necessary, and this continued in operation after chlorine addition stopped. In addition, on the pilot unit the cooling was sufficient to hide any continuing reaction that did occur. 

Chlorine addition may be a prerequisite to sanitize the RO RW supply line and oxidize any organics (followed by dechlorination using sodium bisulfite after the MM filtration stage). Where chlorine is required, it is usual to provide a 20- to 25-minute contact period by means of a temporary storage tank. This is followed by a repressurization pump system. 

Chlorinated hydrocarbons, in cleaning formulations 650 Chlorine addition, for RO pretreatment 367... 

Gaseous chlorine, under room temperature, was bubbled into liquid bromine maintained at -5°C. Excess chlorine left the reactor through a vent into an absorption column. The chlorine addition rate was adjusted to the reactor s cooling capacity, to prevent the temperature from rising above 0°C. 

The HCl produced in this reaction is used in an oxychlorination reaction to chlorinate additional ethylene ... 

Example 14.1 Consider again the chlorination reaction in Example 7.3. This was examined as a continuous process. Now assume it is carried out in batch or semibatch mode. The same reactor model will be used as in Example 7.3. The liquid feed of butanoic acid is 13.3 kmol. The butanoic acid and chlorine addition rates and the temperature profile need to be optimized simultaneously through the batch, and the batch time optimized. The reaction takes place isobarically at 10 bar. The upper and lower temperature bounds are 50°C and 150°C respectively. Assume the reactor vessel to be perfectly mixed and assume that the batch operation can be modeled as a series of mixed-flow reactors. The objective is to maximize the fractional yield of a-monochlorobutanoic acid with respect to butanoic acid. Specialized software is required to perform the calculations, in this case using simulated annealing3. 

The most straightforward way to operate such a process is to maintain a constant chlorine addition rate and a constant temperature. However, both the constant value of the chlorine addition rate and the fixed temperature should be optimized. The temperature of the reaction system is allowed to vary within the set temperature range, but kept constant throughout a batch cycle. The batch time is divided into twenty time... 

The optimization is now constrained to be at a fixed (optimized) chlorine addition rate, but the temperature profile optimized. Profile optimization is used for the temperature, as discussed in Chapter 3. The batch cycle time required is 1.42 h. The resulting fractional yield of MBA from BA now reaches 92.7%. 

The final option is to allow both the chlorine addition profile and temperature profile to be varied through the batch. The optimization shows a further improvement of the objective to 99.8%. It requires 1.35 h of batch cycle time and 75.0 kmol of chlorine. The optimized profiles for reaction temperature and feed addition rate of chlorine are shown in Figure 14.5. 

Dining chlorination of hydrocarbons with Lewis acid catalysis, the catalyst must be premixed with the hydrocarbon before admission of chlorine. Addition of catalyst to the chlorine-hydrocarbon mixture is very hazardous, causing instantaneous release of large volumes of hydrogen chloride. 

It was noted in Section V,B that the chlorophenyl carbene complex 85 can be prepared by chlorine addition to carbyne complex 80. Treatment of 85 with one equivalent of PhLi does not afford 80, suggesting that the reaction sequence is reduction/substitution rather than substitution/reduc-tion. The recent report (127) of a nucleophilic displacement reaction of the molybdenum chlorocarbyne complex 87 with PhLi to generate phenylcar-byne complex 88 suggests that the intermediacy of the chlorocarbyne complex 86 in the above mechanism is not unreasonable. 

A typical polarographic recording is shown in Fig. 2.1 curve (a) is the po-larogram obtained for chlorinated seawater analysed immediately after chlorination. Identical traces were observed for non-chlorinated seawater and for chlorinated seawater kept in the dark for periods up to 24 h at temperatures up to 40 °C, which indicates a lack of bromate formation under these conditions (BrC>3 < 10 7 M, less than 0.5% conversion of chlorine). Addition of copper sulfate to give a cupric ion concentration in the seawater of 100 parts per billion did not induce measurable bromate production in the dark. Curve (b) was obtained from a chlorinated (4.9 mg/1) seawater solution that was exposed to full sunlight for 70 min. Curve (c), which is offset by 0.4 pA with respect to curves (a) and (b), shows the presence of 1.0 x 10 5 M sodium bromate in seawater. 

Chlorinated additive flame retardants, 11 468-470, 471-473t Chlorinated aromatics, 6 242 decomposition using microwaves, 16 555 Chlorinated butyl rubber, 4 436 development of, 4 434 manufacture, 4 400, 442-444 Chlorinated ethanes... 

Flame retardants, 11 447-454, 459-479. See also Fire retardant entries Halogenated flame retardants Phosphorus flame retardants antimony compounds in, 3 54 brominated and chlorinated additive, 11 461-470... 

Other anomeric-oxygen exchange reactions have been recently investigated quite extensively. Closely related to the Koenigs-Knorr method is the introduction offluorine as the leaving group (Scheme 1, path B) (6,9-13). Because of the difference in halophilicity of this element as compared with bromine and chlorine, additional promoter systems besides silver salts were found useful as activators for glycosylation reactions (14-16). However,... 

Even less expected, perhaps, are the reactions involving gas-solid addition of HBr, Cl2, and Br2 to a, 3-unsaturated acid guest species in a- and P-cyclodextrin inclusion complexes (242). Although the chemical yields are not high, the optical yields in some cases are extraordinary. Thus, chlorine addition to methacrylic acid in a-cyclodextrin yields (- )-2,3-dichloro-2-methylpropanoic acid in nearly quantitative optical yield. The 3-cyclodextrin methacrylic acid clathrate undergoes chlorine addition to yield preferentially the enantiomeric (+ )-product, with an e.e. of 80%. 

Fig. 3.68. Analytical HPLC chromatograms with detection of diode array of 4.7 x 10"5mol/l of R3R dye curve (1) before and curve (2) after 180 min of photoelectrocatalysis on the Ti02 thin-film electrode biased at +1.0 V in NajSCT, 0.025 mol/l. Curve (4) before and curve (3) after photoelectrocatalysis in NaCl 0.022 mol/l and curve (5) after bleaching of 4.7 X 10-5 mol/l of R3R dye submitted to a chemical treatment by active chlorine addition. The mobile phase was methanol-water 80 20 per cent with a flow rate of 1 ml/min and controlled temperature at 30°C. The column was a Shimpack (Shimadzu) CLC-ODS, 5 /an (250 mm X 4.6 mm). Reprinted with permission from P. A. Cameiro el al. [138].

The first studies of chlorine addition to the simplest diene, 1,3-butadiene, carried out in solvents of various polarity, showed58 that the reaction always led to mixtures of 1,2- and 1,4-addition products, in ratios almost independent of the solvent polarity. Furthermore, the addition of CI2 in acetic acid gave, besides the 1,2- and 1,4-dichlorides, 3-acetoxy-4-chloro-l-butene and l-acetoxy-4-chloro-2-butene arising from solvent incorporation (equation 27). By comparison of these data with those related to Br2 addition... 

However, a later investigation of the chlorination of the same substrate has shown59b that the product distribution observed immediately after the end of the chlorine addition was markedly different. Small amounts (5%) of the kinetically favored 1,2-dichloride were detected. Furthermore, although the yields of 1,4-dichloro adducts from the two experiments were the same, the yield of the monochloride was much lower in the latter experiment in which detectable amounts of trichlorides were also found. 

According to this mechanism, the first formed ion pair is 19a. Owing to dispersal of charge in the allylic system, the bond between halogen and C(2) is weakened so that an open carbenium ion (19c) readily forms, allowing for the possibility of front-side attack by the anion with the resulting formation of syn 1,2-adducts. This intermediate explains the formation of the cis-],2-adducts by chlorine addition to cyclic systems. However, syn 1,2-dichlorides can also result from linear dienes by rotation around the C(l)—C(2) bond in 19c to produce 19d, followed by back-side attack by the anion with respect to its position in 19d. Syn 1,4-adducts should instead arise by attack of the anion on C(4) in either 19a, 19c or 19d. Formation of anti dichlorides (1,2- or 1,4-) can only occur when there is appreciable translocation in the ion pair 19a to give 19b. Attack by the anion at C(2) in 19b yields anti 1,2-dichloride and attack at C(4) yields anti 1,4-dichloride. 

More recent data61 on the chlorination of 1,3-pentadienes have confirmed that chlorine addition in 1,2-dichloroethane or carbon tetrachloride gives 4,5- and 1,4-dichloro-2-pentenes as main products, besides smaller amounts of 3,4-dichloropentenes, although chloropentenes have been detected as minor products. Furthermore, it has been shown that the yields of the latter products are reduced when the reaction is carried out in the presence of quaternary ammonium or phosphonium salts. 

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