▁eth an ium , ▁ ▁( pro ton ated ▁eth ane ) ▁prop an ium , ▁ ▁( prop ane ▁pro ton ated ▁on ▁an ▁un spec ified ▁carbon ) ▁pro py li um , ▁or ▁prop an - 1 - y li um ▁( prop ane ▁pro ton ated ▁on ▁an ▁end ▁carbon ) ▁prop an - 2 - y li um ▁( prop ane ▁pro ton ated ▁on ▁the ▁middle ▁carbon ) ▁but an ium , ▁ ▁( but ane ▁pro ton ated ▁on ▁an ▁un spec ified ▁carbon ) ▁n - but an ium ▁( n - but ane ▁pro ton ated ▁on ▁an ▁un spec ified ▁carbon ) ▁n - but y li um , ▁or ▁n - but an - 1 - y li um ▁( n - but ane ▁pro ton ated ▁on ▁an ▁end ▁carbon ) ▁n - but an - 2 - y li um ▁( n - but ane ▁pro ton ated ▁on ▁a ▁middle ▁carbon ) ▁is ob ut an ium ▁( is ob ut ane ▁pro ton ated ▁on ▁an ▁un spec ified ▁carbon ) ▁is ob ut y li um , ▁or ▁is ob ut an - 1 - y li um ▁( is ob ut ane ▁pro ton ated ▁on ▁an ▁end ▁carbon ) ▁is ob ut an - 2 - y li um ▁( is ob ut ane ▁pro ton ated ▁on ▁the ▁middle ▁carbon ) ▁oct on ium ▁or ▁oct an ium , ▁ ▁( pro ton ated