1304
Due to the spatial configuration , the direct proton migration from the N atoms of ethylenediamine to urea is difficult to occur .
 Chemical: N; Chemical: ethylenediamine; Chemical: urea
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: N; Chemical: ethylenediamine; Chemical: urea