Author Topic: Ye olde preparation of bromine  (Read 921 times)

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Ye olde preparation of bromine
« on: July 26, 2003, 04:26:00 PM »
Taken from 'Chemische experimente, die gelingen', dr. Hermann Römmp, 1939  p 49-50 :


In its pure form bromine is a deep red-brown coloured liquid from which evolve at room temperature redbrown, heavy, poisonous fumes that smell sharp and chlorine-like. Bromine fumes colour (potato-)starch yellow.

Bromine is very poisonous, 0.001% bromine fumes in the air are already dangerous by inhalation for a couple of hours. It also causes serious burns on the skin.
For storage use a bottle with a tightly-closing ground-glass stopcock. Do not use cork.

It is best to prepare pure bromine when needed, what is not used can then be dissolved in water, to make bromine-water which can be stored with much less dangers.

(Small scale) preparation:

In a mortar 5 grams of potassium bromide (KBr) is grinded to a powder, and this is mixed with 10 grams of manganese dioxide (MnO2) powder. This is then carefully added through the tubus to the retort  ;D , making sure no powder adheres to the neck of the retort. 150 cc of dilute sulfuric acid (1 part H2SO4 with 5 parts water) is then also added through the tubus of the retort.

In a fume-hood or in front of an open window  8)  the retort is carefully heated, and the recieving flask is well cooled in ice. The bromine fumes cool and liquify to form a small amount of liquid bromine.
Note: better use the fume-hood, especially for larger scale experiments.

1000 cc water can dissolve 35 g Br2, to make bromine-water.
This preparation is not adviced for the beginning experimenter !

- I thought this was a nice piece of old-school inorganic chemistry, so I decided to post it. The book was written for 'everyone who wants to learn chemistry by experimenting theirselves', the authors ends his introduction with the words 'Afterall I speak out the wish, that this book may recruit many new friends for our so beautiful and interesting chemistry.'  :)

I really love those old chem books and their idealistic authors.


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Old books
« Reply #1 on: July 27, 2003, 02:39:00 AM »

I really love those old chem books and their idealistic authors.

Me too...and especially the one author who wrote the abovementioned and a lot of other interesting books, not to mention his famous work "Chemie-Lexikon" (Roempps Encyclopedia of Chemistry)  ;D
These old books can still be bought from our favorite auction site, are well worth reading and are highly recommended. Too bad that these books are not published in English  ::)


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alternate route?
« Reply #2 on: August 03, 2003, 09:21:00 AM »
hi all-
just postulating here, no stoichiometry, all eyeballing:
(all in a mayonnaise jar)ground KBr, added to a mixture of 3% H2O2 and ~31% HCl, is cooled in running cold water.


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That is a very bad idea.
« Reply #3 on: August 03, 2003, 03:17:00 PM »
That is a very bad idea. Get yourself a scale and pyrex beakers.


  • Guest
Bromine from Seawater
« Reply #4 on: August 03, 2003, 03:55:00 PM »
(from Ullmann`s) Seawater Process

The first economically successful recovery of bromine directly from the sea was carried out near Wilmington, North Carolina (USA), using an air-blowing process originally developed for brine operations by H. H. DOW [28]. The use of air rather than steam is necessary because the cost of steam to heat ocean water, with its bromine content of only about 65 mg/L, would be prohibitive. The Wilmington plant has since been abandoned, but the process is still employed, e.g., at Amlwich (Wales) and Hayle (Cornwall).
Water from the ocean is pumped to the top of blowing-out towers, with sulfuric acid and chlorine being added just above the pumps so that mixing takes place during the ascent. About 1.3 kg of 10 % sulfuric acid per ton of water is required to neutralize the natural hydrogen carbonates and bring the pH to 3.5; 15 % excess chlorine over the theoretical requirement is used [29].Air is drawn up through the towers, sweeping out a mixture of bromine and chlorine (or bromine chloride) from the descending ocean water. The air is drawn next through absorber towers in which it is scrubbed counter-currently by sodium carbonate solution. The several reactions which take place may be summarized approximately by the equation:
3 Na2CO3 + 2 Br2 + BrCl  -> NaBrO3 + 4 NaBr + NaCl + 3 CO2
To remove spray from the air, small packed chambers are interposed between the absorber towers and the fans. When the alkalinity of the scrubber solution is nearly depleted, the solution is brought first to a storage tank and then to a reactor in which it is treated with sulfuric acid and steamed to release bromine:
NaBrO3 + 5 NaBr + 3 H2SO4 --> 3 Br2 + 3 Na2SO4+ 3 H2O
The bromine is condensed and used in the manufacture of ethylene dibromide.
In a modification of the process [30] , [31] , which was used for a number of years at Freeport, Texas, halogens blown from the ocean water are reduced with sulfur dioxide and absorbed in a water spray:
Br2 + SO2 + 2 H2O --> 2 HBr + H2SO4
BrCl + SO2 + 2 H2O --> HBr + HCl + H2SO4
The resulting aqueous solution of mixed acids is treated with chlorine in a conventional steam-out tower and the bromine is recovered. The mixture of hydrochloric and sulfuric acid remaining is used for acidifying the raw ocean water.
The SO2 process has been described [32]; further details of its operation at Freeport and the automatic controls employed there are available [33]. Normal flow of incoming gulf water is 568 m3/min; the rubber-lined riser pipe is about 12 m tall and 2.1 m in diameter. A glass electrode at the top of the riser measures the pH to within 0.02 unit and controls "butterfly" valves in a return line on the acid supply pumps. Oxidation potential is controlled at about 970 mV with a platinum electrode and a saturated calomel reference electrode, regulating the addition of chlorine. Oxidation potential measurements are also used to control the mixing of sulfur dioxide with the free halogen vapor stream and the chlorination of the reduced acid mixture.
Analytical methods used for bromide in brines and ocean water have been described [34]. Usually the van der Meulen method [35] or one of its various modifications is employed. Economic factors important in the location of seawater bromine plants, especially as they were related to the siting of the Amlwich operation, have been discussed [36]; temperature of the water has a significant effect on the efficiency of the blowing-out process [32].
Because of the large volume of ocean water processed, the bromine-depleted stream must be discharged at some distance from the intake and in a favorable location from the standpoint of prevailing currents, to avoid dilution. Aside from this, waste disposal is not a problem since both the acidity and the free halogen content of the outgoing water are very low. In contrast, the waste stream from a strong brine process requires neutralization and, in some instances, reduction. In most cases, spent well brine is returned to the ground via disposal wells to maintain hydrostatic pressure within the formation. Acidity or free halogens should be absent to minimize corrosion of the system. Lime or caustic soda are customarily used for neutralizing acidity. The use of semiburnt dolomite with sodium thiosulfate has been recommended [37].

[28]  Dow Chemical, US 460370 (1891).
[29]  L. C. Stewart, Ind. Eng. Chem. 26 (1934) 361.
[30]  Dow Chemical, US 2143223, 1939.
[31]  Dow Chemical, US 2143224, 1939.
[32]  C. M. Shigley, J. Metals 3 (January, 1951) 25.
[33]  P. Hart, Bull. Agric. Mech. Coll. Tex. 5 (3) (1947) no. 2, 59;Instruments 20 (1947) 956.
[34]  J. Haslam, G. Moses et al., Analyst. (London) 75 (1950) 343, 352, 357, 371, 383.
[35]  J. H.van der Meulen, Chem. Weekbl. 28 (1931) 238.
[36]  H. Fossett, Chem. Ind. (London) 1971 no. 41, 1161.
[37]  H. Kloth, B. Peter, Bergakademie 22 (1970) no. 10, 628.