25112
The homolytic cleavage of peroxide bonds , leading to the formation of free radicals , plays an important role in the ( spontaneous ) oxidation of a wide variety of hydrocarbons in the presence of oxygen .
 peroxide, hydrocarbons, oxygen
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 peroxide, hydrocarbons, oxygen