20708
These catalysts generate the symmetrical ether as a by - product from the reactions of S - , C - , and N - centered nucleophiles as well , resulting in lower chemoselectivity .
 Chemical: S; Chemical: C; Chemical: N
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: S; Chemical: C; Chemical: N