an ▁is ▁a rom atic ▁because ▁one ▁of ▁the ▁l one ▁pairs ▁of ▁electrons ▁on ▁the ▁o xygen ▁atom ▁is ▁del ocal ized ▁into ▁the ▁ring , ▁creating ▁a ▁ 4 n   +   2 ▁a rom atic ▁system ▁( see ▁H ück el ' s ▁rule ) ▁similar ▁to ▁ben z ene . ▁ ▁Because ▁of ▁the ▁a rom atic ity , ▁the ▁mole c ule ▁is ▁flat ▁and ▁la cks ▁discrete ▁double ▁b onds . ▁The ▁other ▁l one ▁pair ▁of ▁electrons ▁of ▁the ▁o xygen ▁atom ▁extends ▁in ▁the ▁plane ▁of ▁the ▁flat ▁ring ▁system . ▁The ▁sp 2 ▁hy brid ization ▁is ▁to ▁allow ▁one ▁of ▁the ▁l one ▁pairs ▁of ▁o xygen ▁to ▁res ide ▁in ▁a ▁p ▁orb ital ▁and ▁thus ▁allow ▁it ▁to ▁interact ▁within ▁the ▁ π ▁system . ▁ ▁Due ▁to ▁its ▁a rom atic ity , ▁fur an ' s ▁behavior ▁is ▁quite ▁dis similar ▁to ▁that ▁of ▁the ▁more ▁typical ▁heter oc yc lic ▁eth ers ▁such ▁as ▁t et rah ydro fur an . ▁▁ ▁It ▁is ▁consider ably ▁more ▁re active ▁than ▁ben z ene ▁in ▁elect roph il ic ▁substitution ▁re actions , ▁due ▁to ▁the ▁electron - don ating ▁effects ▁of ▁the ▁o xygen ▁heter o atom . ▁Ex am ination ▁of ▁the ▁reson ance ▁contrib utors ▁shows ▁the ▁increased ▁electron ▁density ▁of ▁the ▁ring , ▁leading ▁to ▁increased ▁rates ▁of ▁elect roph il ic ▁substitution . ▁▁ ▁Fur an ▁serves ▁as ▁a ▁di ene ▁in ▁D