fɹˈiː ɹˈædɪkəlz, mˈɑːlɪkjˌuːlz wɪð ʌnpˈɛɹd ᵻlˈɛktɹɑːnz, plˈeɪ ɐ lˈɑːɹdʒ ɹˈoʊl ɪn mˈoʊst ɹɪˈækʃənz ʌv ˈælkeɪnz, sˈʌtʃ ɐz kɹˈækɪŋ ænd ɹᵻfoːɹmˈeɪʃən wˌɛɹ lˈɔŋtʃˈeɪn ˈælkeɪnz ɑːɹ kənvˈɜːɾᵻd ˌɪntʊ ʃˈɔːɹɾɚtʃˈeɪn ˈælkeɪnz ænd stɹˈeɪttʃˈeɪn ˈælkeɪnz ˌɪntʊ bɹˈæntʃttʃˈeɪn ˈaɪsəmɚz.
Free radicals, molecules with unpaired electrons, play a large role in most reactions of alkanes, such as cracking and reformation where long-chain alkanes are converted into shorter-chain alkanes and straight-chain alkanes into branched-chain isomers.