▁i od ine ▁ox ides , ▁as ▁they ▁are ▁all ▁fairly ▁un stable : ▁it ▁was ▁once ▁thought ▁that ▁they ▁could ▁not ▁exist ▁at ▁all . ▁D ib rom ine ▁mon ox ide ▁is ▁a ▁dark - b rown ▁solid ▁which , ▁while ▁reason ably ▁stable ▁at ▁− 6 0   ° C , ▁decom poses ▁at ▁its ▁mel ting ▁point ▁of ▁− 1 7 . 5   ° C ; ▁it ▁is ▁useful ▁in ▁b rom ination ▁re actions ▁and ▁may ▁be ▁made ▁from ▁the ▁low - temper ature ▁decomposition ▁of ▁b rom ine ▁dio x ide ▁in ▁a ▁vac u um . ▁It ▁ox id ises ▁i od ine ▁to ▁i od ine ▁pent ox ide ▁and ▁ben z ene ▁to ▁ 1 , 4 - ben zo quin one ; ▁in ▁al kal ine ▁solutions , ▁it ▁gives ▁the ▁hyp ob rom ite ▁an ion . ▁ ▁So - called ▁" b rom ine ▁dio x ide ", ▁a ▁pale ▁yellow ▁cry st all ine ▁solid , ▁may ▁be ▁better ▁form ulated ▁as ▁b rom ine ▁per b rom ate , ▁Br O Br O 3 . ▁It ▁is ▁therm ally ▁un stable ▁above ▁− 4 0   ° C , ▁viol ently ▁decom pos ing ▁to ▁its ▁elements ▁at ▁ 0   ° C . ▁D ib rom ine ▁tri ox ide , ▁syn - Br O Br O 2 , ▁is ▁also ▁known ; ▁it ▁is ▁the ▁an h yd ride ▁of ▁hyp ob rom ous ▁acid ▁and