21266
An unexpected trans - cis isomerization is observed during Hg / Al reduction of the 1 - pyrazoline NN bond .
 Chemical: Hg; Chemical: Al; Chemical: 1 - pyrazoline; Chemical: NN
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: Hg; Chemical: Al; Chemical: 1 - pyrazoline; Chemical: NN