Free radicals are the reactive species that participate in the reaction, which usually leads to a mixture of products.
fɹˈiː ɹˈædɪkəlz ɑːɹ ðə ɹɪˈæktɪv spˈiːsiːz ðæt pɑːɹtˈɪsᵻpˌeɪt ɪnðə ɹɪˈækʃən, wˌɪtʃ jˈuːʒuːəli lˈiːdz tʊ ɐ mˈɪkstʃɚɹ ʌv pɹˈɑːdʌkts.