Dear Syadza, sorry to see that your very interesting technical question has not been answered yet. Many years ago we did a lot of work involving 1,3,5-tris(trifluoromethyl)benzene. This was made by converting the –COOH groups of 1,3,5-benzene-tricarboxlic acid into –CF3 groups by means of SF4. However, work with SF4 requires especially equipped laboratories. For the direct trifluoromethyl substitution of aromatic rings please have a look e.g. at the following useful article:

Trifluoromethylation of arenes and heteroarenes by means of photoredox catalysis

https://macmillan.princeton.edu/wp-content/uploads/Arene-Trifluoromethylation.pdf

(see attached pdf file)

Also please see this very instructive review article:

Aromatic Trifluoromethylation with Metal Complexes

https://pubs.acs.org/doi/abs/10.1021/cr1004293?journalCode=chreay&quickLinkVolume=111&quickLinkPage=4475&selectedTab=citation&volume=111

Unfortunately this paper is not available as public full text on RG. It is also worth a try to search the "Publications" section of RG directly for the term "trifluoromethylation of aromatic rings":

https://www.researchgate.net/search.Search.html?type=publication&query=trifluoromethylation%20of%20aromatic%20rings

Good luck with your research and best wishes, Frank Edelmann

Dear Frank T. Edelmann , thank You very much for your answer. It is really useful for our work.