9613
In the reduction of 4 - oxo - 2 - nonenal , the catalytic efficiency was increased .
 4 - oxo - 2 - nonenal
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 4 - oxo - 2 - nonenal