10846
In an interesting example of a molecule containing two CF ( 3 ) groups getting simultaneously involved in hydrogen bond , where hydrogen bond mediated couplings are not reflected in the NMR spectrum , ( 19 ) F - ( 19 ) F NOESY experiment yielded confirmatory evidence .
 CF ( 3 ), hydrogen, hydrogen, ( 19 ) F, ( 19 ) F
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 CF ( 3 ), hydrogen, hydrogen, ( 19 ) F, ( 19 ) F