Method for making bromides
AssigneeLANXESS Solutions US Inc.
InventorsThomas G. Ray, David W. Bartley, Hugh Broadhurst, Nate Goodwin
Life of this patent
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Abstract
Bromine containing compounds, such as calcium bromide, sodium bromide and the like, are prepared in high purity and more quickly with less waste by using a process with two bromination stages and often a third step wherein the crude product mixture can be adjusted to meet specific product requirements. In the first bromination stage, the majority, but not all, of a substrate is brominated using a reductive bromination reaction, the remaining unreacted substrate is converted to product in the second stage through another a reductive bromination reaction, although the specific reagents may be different, wherein the addition of bromine and a reducing agent are carefully monitored.
Claims16
A process for producing a compound of formula RBrn, wherein R is an alkali or alkali earth metal and n is 1 or 2, said process comprising:
- I) a first stage wherein a mixture comprising a first reducing agent and a substrate of formula RpXm,
- wherein R is a Group 1 metal or a Group 2 metal;
- m is a number 1 or 2;
- p is a number 1 or 2;
- and X is oxygen atom, carbonate, bicarbonate or OH;
- is reacted with an amount of bromine necessary to brominate from about 70 to about 98% of RXm to RBrn to provide an intermediate mixture comprising RBrn and residual substrate RXm, wherein at least a portion of the first stage is run at a reaction temperature of 50° C. or higher and/or at greater than atmospheric pressure, and
- II) a second stage wherein a second reducing agent, different from the first reducing agent, and an amount of bromine needed to provide 100% conversion of residual substrate RXm are separately added to the intermediate mixture from I), forming a reaction product mixture, wherein addition of the second reducing agent and bromine in the second stage are continuously adjusted to maintain or re-establish the pH and oxidation/reduction potential of the reaction mixture during the second stage within predetermined ranges by increasing, suspending or slowing addition of bromine when the pH of the reaction mixture is outside of a predetermined range until the predetermined pH range is re-established, and by increasing, suspending or slowing addition of the second reducing agent when the oxidation/reduction potential of the reaction mixture is outside of a predetermined range until the predetermined oxidation/reduction potential range is re-established.
Dependencies are inferred from the claim text.