2 questions about organic chemistry

[DYH0310]

1.In the process of nitrifying benzene with nitric acid,the use of HFIP can make the nitrification reaction condition milder

How could this work?

2.In the reaction of 2-chloropyrazine with thiophenol, the reaction did not occur if the solvent was isopropanol(ipr) ,wherean the produce was obtained in 94% yield whit HFIP(300K,12h)

How could this work???

[stephmayo]

1. HFIP in Organic Synthesis

   Hashim F. Motiwala, Ahlam M. Armaly, Jackson G. Cacioppo, Thomas C. Coombs, Kimberly R. K. Koehn, Verrill M. Norwood IV, and Jeffrey Aubé
   Chemical Reviews 2022 122 (15), 12544-12747
   DOI: 10.1021/acs.chemrev.1c00749

this article seems to explain the mechanisms