▁of ▁this ▁reaction ▁can ▁be ▁improved ▁by ▁the ▁use ▁of ▁z inc ▁as ▁the ▁de hal ogen ating ▁agent ▁and ▁sod ium ▁i od ide ▁as ▁a ▁catal yst . ▁ ▁Br CH 2 CH 2 CH 2 Br ▁ ▁+ ▁▁ 2 ▁Na ▁ ▁→ ▁ ▁( CH 2 ) 3 ▁ ▁+ ▁▁ 2 ▁Na Br ▁ ▁Cy clo prop an ation ▁ ▁Cy clo prop ane ▁rings ▁are ▁found ▁in ▁numerous ▁bi om ole cules ▁( e . g ., ▁py re th r ins , ▁a ▁group ▁of ▁natural ▁insect ic ides ) ▁and ▁ph arma ce ut ical ▁dru gs . ▁As ▁such ▁the ▁formation ▁of ▁cy clo prop ane ▁rings , ▁generally ▁referred ▁to ▁as ▁cy clo prop an ation , ▁is ▁an ▁active ▁area ▁of ▁chemical ▁research . ▁ ▁Re actions ▁O wing ▁to ▁the ▁increased ▁ π - character ▁of ▁its ▁C - C ▁b onds , ▁cy clo prop ane ▁can ▁react ▁like ▁an ▁alk ene ▁in ▁certain ▁cases . ▁For ▁instance ▁it ▁under go es ▁hydro hal ogen ation ▁with ▁min eral ▁ac ids ▁to ▁give ▁linear ▁alk yl ▁hal ides . ▁Sub st it uted ▁cy clo prop anes ▁also ▁react , ▁following ▁Mark ov nik ov ' s ▁rule . ▁Sub st it uted ▁cy clo prop anes ▁can ▁ox id atively ▁add ▁to ▁transition ▁met als , ▁in ▁a ▁process ▁referred ▁to ▁as ▁C – C ▁activation . ▁ ▁Cy clo pro py l ▁groups ▁adjacent ▁to ▁vin yl ▁groups