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Chromium(III) bromide
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<h2 id="synthesis">Synthesis</h2> <p>The compound is prepared in a tube furnace by the reaction of <a href="/facts/Bromine/oLfj3C7D">bromine</a> vapor and chromium powder at 1000 °C. It is purified by <a href="/facts/Extraction_(chemistry)/Df7wExz9">extracting</a> with absolute <a href="/facts/Diethyl_ether/Ep20vEdj">diethyl ether</a> to remove any <a href="/facts/Chromium(II)_bromide/1K3eNSJJ">CrBr2</a>, and is subsequently washed with absolute diethyl ether and <a href="/facts/Ethanol/3lCLfBSP">absolute ethanol</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> </p> 2Cr + 3Br2 → 2CrBr3 <p>The effect of bromine on a highly heated mixture of <a href="/facts/Chromium(III)_oxide/5C6XdjrQ">chromium(III) oxide</a> with coal: </p> Cr2O3 + 3Br2 + 3C → 2CrBr3 + 3CO <h2 id="chemical-properties">Chemical properties</h2> <p>Analogous to the behavior of related chromium(III) halides, the tribromide dissolves in water to give CrBr3(H2O)3 only upon the addition of catalytic amounts of a reducing agent, which generates CrBr2.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> The reducing agent generates chromous bromide on the surface of the solid, which dissolves and re-oxidizes to Cr(III). </p><p>Chromium(III) bromide is reduced by <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> gas at 350-400 °C to give <a href="/facts/Chromium(II)_bromide/1K3eNSJJ">chromium(II) bromide</a>:<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> 2 CrBr3 + H2 → 2 CrBr2 + 2 HBr <p>Oxidizes when heated in air: </p> 2 CrBr3 + 3 O2 → 2 Cr2O3 + 6 Br2 <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). Vol. 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1340. ISBN 978-0-32316129-9. Retrieved 2014-01-10. <a href="978-0-32316129-9" target="_blank">978-0-32316129-9</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). Vol. 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1340. ISBN 978-0-32316129-9. Retrieved 2014-01-10. <a href="978-0-32316129-9" target="_blank">978-0-32316129-9</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). Vol. 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1340. ISBN 978-0-32316129-9. Retrieved 2014-01-10. <a href="978-0-32316129-9" target="_blank">978-0-32316129-9</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> </ol>