Bromine continued

Demands for bromine continue to increase throughout the world at a rate predicted to equal to 2% per year. Such an estimate of bromine consumption growth is warranted by increasing production of antidetonators for motor fuel, flameproof plastics, pesticides, and high-density fluids for the deep borehole in the petrol industry. 

The method used by Lowig and Balard to collect bromine continues to be used today. Chlorine is added to seawater containing sodium bromide or potassium bromide. Chlorine is more active than bromine and replaces bromine in the reaction ... 

Pyronil 63, a melt processable solid flame retardant containing 63% bromine, continues under development. 

Dibromide formation. Dissolve 0 2 ml. of styrene in 0 5 ml. of CCI4 in a test-tube. Add slowly, drop by drop, a 10% solution of bromine in CCI4. Note the decolorisation of the bromine and absence of HBr fumes (therefore reaction by addition and not by substitution). Continue to add the bromine solution until a faint brown colour persists. Scratch the sides of the tube and cool it in ice-water. Filter off the crystals that separate and recrystallise the styrene dibromide from methanol m.p. 72 . 

Procedure for Bromine and Iodine Estimations. Again cover the beaker as before, but before adding the nitric acid add i g. of hydrazine sulphate and heat the solution on the water-bath until evolution of gas ceases. To ensure complete decomposition of an iodate, however, the heating should be continued for i hour. 

Dibromobutane (from 1 4-butanediol). Use 45 g. of redistilled 1 4-butanediol, 6-84 g. of purified red phosphorus and 80 g. (26 ml.) of bromine. Heat the glycol - phosphorus mixture to 100-150° and add the bromine slowly use the apparatus of Fig. Ill, 37, 1. Continue heating at 100-150° for 1 hour after all the bromine has been introduced. Allow to cool, dilute with water, add 100 ml. of ether, and remove the excess of red phosphorus by filtration. Separate the ethereal solution of the dibromide, wash it successively with 10 per cent, sodium thiosulphate solution and water, then dry over anhydrous potassium carbonate. Remove the ether on a water bath and distil the residue under diminished pressure. Collect the 1 4-dibromobutane at 83-84°/12 mm. the yield 3 73 g. 

Continue the passage of bromine vapour until the solution in A assumes a distinctly yellow colour (2-3 hours) the reaction is then complete. Filter the tribromoaniline on a Buchner funnel, wash it thoroughly with water to remove hydrobromic acid, and suck as dry as possible. Ilecr3 stallise from methylated (or rectified) spirit. The yield is 22 g. m.p. 120°. 

METHYL y-BROMOCROTONATE JV-Bromosuccinimide. Dissolve, with the aid of rapid mechanical stirring, 80 g. of pure succinimide (Section V,14) in a mixture of 150 g. of finely crushed ice and a solution of 32 g. of sodium hydroxide in 200 ml. of water contained in a litre beaker and cooled externally by ice. Immediately the imide has dissolved, continue the vigorous stirring and introduce 42 -5 ml. of bromine in one lot from a separatory funnel supported over the beaker it is essential that the bromine be instantly suspended in the solution. After stirring vigorously for 2 minutes, filter at the pump and... 

Nitrosomethylurea. Acetamide method. To a solution of 59 g. of acetamide in 88 g. (28 ml.) of bromine (1) in a 4-litre beaker add dropwise, with hand stining, a solution of 40 g. of sodium hydroxide in 160 ml. of water. Heat the resulting yellow reaction mixture on a steam bath until eflfervescence sets in (2), after which continue the heating for 2-3 minutes. CrystaUisation of the product from the yellow or red coloured solution usually commences immediately. Cool in an ice bath for 1-2 hours, collect the product by suction filtration, wash with a little ice-cold water, and dry in the air. The yield of colourless acetylmethylurea, m.p. 178-180°, is 50 g. 

To a stirred, cooled (0°C) solution of I52.15g (1.0 mol) of vanillin in 1000ml of methanol was added during 20 min 176.Og (1.1 mol) of bromine at such a rate that the temperature was kept below 20°C. The mixture was stirred at room temperature for lh, cooled to 0°C, and treated during 30 min with 500 ml of cold (5°C) water. Stirring was continued for 15 min and the product was collected by filtration. It was washed with water (4x500 ml), then with 500 ml of... 

Continual use of decabromidiphenyl oxide has been placed ia question based on the discovery that under certain laboratory conditions brominated dibenzo- -dioxias are generated (63). The condition most often employed ia such studies is pyrolysis of milligram-scale samples at 600°C. This temperature is higher than polymer processiag conditions and lower than fire temperatures, ie, the conditions are not representative of actual conditions to which flame-retardant polymers are exposed. 

Bromine Trifluoride. Bromine trifluoride is produced commercially by the reaction of fluorine with bromine ia a continuous gas-phase process where the ratio of fluorine to bromine is maintained close to 3 1. It is also produced ia a Hquid-phase batch reaction where fluorine is added to Hquid bromine at a temperature below the boiling poiat of bromine trifluoride. 

Eigure 3 is a flow diagram which gives an example of the commercial practice of the Dynamit Nobel process (73). -Xylene, air, and catalyst are fed continuously to the oxidation reactor where they are joined with recycle methyl -toluate. Typically, the catalyst is a cobalt salt, but cobalt and manganese are also used in combination. Titanium or other expensive metallurgy is not required because bromine and acetic acid are not used. The oxidation reactor is maintained at 140—180°C and 500—800 kPa (5—8 atm). The heat of reaction is removed by vaporization of water and excess -xylene these are condensed, water is separated, and -xylene is returned continuously (72,74). Cooling coils can also be used (70). 

Bromination of sulfolane by BrCl under uv irradiation gives 2-bromosulfolane [29325-66 ] which reacts further to give i7j -2,5-dibroniosulfolane [30186-52-8] (5). Continued irradiation converts the <7j -isomer to /n j -2,5-dibroniosulfolane [30186-54-0] which yields first the trans-2 4 isomer [30186-53-9] and then the trans-2 4 isomer [15091 -30-2] upon further irradiation. 

Even when their shells are closed, the animals continue to sense their environment, and as soon as the oxidant level decreases, they reopen and resume siphoning. Continuous chlorination often fails to eradicate these macrofouling creatures because of iatermptions ia the feed, which can occur for various reasons, such as chlorine tank changeover or plugging of feedlines. If the iatermption lasts long enough (1 h or possibly less), the animals have time to reoxygenate their tissues between the extended periods of chlorination. Any oxidant, such as chlorine, bromine, or ozone, eUcits the same response from these creatures. Therefore, only continuous, unintermpted appHcations are successful. 

Chlorine and bromine add to benzene in the absence of oxygen and presence of light to yield hexachloro- [27154-44-5] and hexabromocyclohexane [30105-41-0] CgHgBr. Technical benzene hexachloride is produced by either batch or continuous methods at 15—25°C in glass reactors. Five stereoisomers are produced in the reaction and these are separated by fractional crystallization. The gamma isomer (BHC), which composes 12—14% of the reaction product, was formerly used as an insecticide. Benzene hexachloride [608-73-17, C HgCl, is converted into hexachlorobenzene [118-74-17, C Clg, upon reaction with ferric chloride in chlorobenzene solution. 

The first pubHshed information on the halogenation of butyl mbber was provided by B. F. Goodrich Co. (2). Brominating agents such as /V-bromosuccinimide were used the bromination occurred ia a bulk reaction. This technology was commercialized ia 1954, but withdrawn ia 1969 (3). Exxon Chemical researchers pursued the chlorination of butyl mbber ia hexane solution usiag elemental chlorine, and a continuous process was commercialized ia 1961 (4). Currentiy, both chlorination and bromination are carried out ia continuous-solution processes. 

The alkaline solution is cooled to room temperature and, with the stirrer still in constant operation, and after inserting a thermometer, r6o g. (i mole) of bromine is added from a dropping funnel in the course of twenty to thirty minutes. During this operation the temperature is allowed to rise to 40-50Stirring is continued for one-half hour after all of the bromine has been added. The solution should still be alkaline and should contain only a small amount of suspended material. 

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