Science of Synthesis

Sellars, J. D., Science of Synthesis Knowledge Updates, (2014) 1, 403.

Whilst p- and d-block metal trifluoromethanesulfonates have promoted the formation of aryl ketones from arenes and acid chlorides or anhydrides, so too have lanthanide trifluoromethanesulfonates, particularly those of scandium and ytterbium.[‌30‌] Scandium(III) trifluoromethanesulfonate and ytterbium(III) trifluoromethanesulfonate have both demonstrated catalytic activity in the Friedel–Crafts reaction of acid chlorides at catalyst loadings as low as 2 mol%, whereas the use of anhydrides requires the addition of lithium perchlorate in nitromethane to accelerate the reaction. Changing the solvent to supercritical carbon dioxide (scCO2) removes the need for additives and reduces the production of toxic waste products.[‌12‌,‌31‌] As with the titanium and hafnium systems (cf. Section ‌26.8.4.1.1.1.2‌), trifluoromethanesulfonate ligands make for good Lewis acidic metals, and lanthanide perfluorooctanesulfonates provide a recyclable catalyst system in the presence of perfluorooctanesulfonic acid and octadecafluorodecahydronaphthalene (perfluorodecalin) as solvent. All the lanthanide perfluorooctanesulfonates have been produced and have demonstrated admirable activity in the Friedel–Crafts acylation of benzene with benzoyl chloride to give benzophenone (‌3‌, R1 = R2 = H; ‌Scheme 10‌).[‌32‌]

‌Meeeee 88‌ Meeeeee–Meeeee Meeeeeeee eeee Meeeeeeeee eee Meeeeeee Meeeeeeeeee­eeeeeeeeeeeee Meeeeeeee[‌88‌]

‌Meeeeeeeeee 88‌

Meeee eeeeeeeeee(MMM) eeeee eeee eeee eeee eeee, eeeeeee eeeeeeee(MMM) eeeeee, eeeee ee 88 eee% eeeeeee eee eeeeeee eeeeeee eee eeeee eeeeeeee-eeee eeeeee eeee eee eeeeeeeeeeeee eeee eeeeeee ee eeee eeeee ee eeeeeeee eeee eeee eeeeeeeee.[‌88‌] Me eeeeeeeeee eeeeeeeeee ee eeeeee ee eeeee eeee eeeeeeee eeee eeeeee(MMM) eeeeeeeeeeeeeeeeeeeeeeeee ee ee eeeeeeeeeee eeeeeeee ee eee Meeeeee–Meeeee eeeeeeee. Meeeeee, eeeeeee eeeeee ee eeeeeeeeee eeeeee eeeeee(MMM) eeeeeeeeeeeeeeeeeeeeeeeee ee eeeeeeee eee eeeeeeeee ee eeeeeeee-eeee ee­eeee eeee eeeeeeeeee.[‌88‌] Meeeeeeee eee eeeeeeeeeee, eee eeeeeeeee eeee eeeeeeee eeeeeee ee eeee eeeeeeee eeee eeeeeee(MM) eee eeeeeee(MM) eeeee, eeee ee eeeeeee(MM) eeeeeeee, eeeeeeeeeeeee eeeeeeeeee eeeeeeeee eeeeeeee (8 eee%) eee eeeeeeeeeeeeeeee ee eee eeeeeeee ee eeeeeeee-eeee eeeeee eee eeee eeeeeeeee ee eeee, eee eeeeeee, 8-eeeeeeeeeeeeeeeeeee (‌8‌) (‌Meeeee 88‌).[‌88‌]

‌Meeeee 88‌ Meeeeee–Meeeee Meeeeeee eeee Meeeeee(MM) Meeeeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeeee (‌8‌, M8 = M8 = M); Meeeeee Meeeeeeee:[‌88‌]

MeMe (8.8 eM, 88 eeee) eee eeeeee eeeee eeee e eeeeeee ee Me[M8M(MM8)8MM8]8 (88 ee, 8.888 eeee), MM8(MM8)8MM8M (88 ee, 8.888 eeee), eeeeeee (8.8 eM, 88 eeee) (MMMMMMM: eeeeeeeeee), eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee (eee/eeeee eeeeeee; 8.8 eM). Mee eeeeeee eee eeeeeee ee 88 °M eee 88 e, eee eeee eee eeeeeeee eeeee ee eee eeeeee eee eeeeeeeee eee eee eeee eeeeeeeee. Mee eeeeeee (eeeeeee eeeee) eee eeeeee eeee 88% ee MeMMM8 (88 eM) eee M8M (8 × 88 eM). Mee eeeeeeee eeee eeee eeeeeeeee eeee Me8M, eee eee eeeeeeee eeeeeee eeeeee eeee eeeee (Me8MM8). Mee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeeeee eeeee/MeMMe 88:8) ee eeee eee eeeeeee ee e eeeee eeeee; eeeee: 8.88 e (88%).

8-Meeeeeeeeeeeeeeeeee (‌8‌); Meeeeee Meeeeeeee:[‌88‌]

Me e eeeeeeee, MMe8 (88 ee, 8.8 eeee) eee eeeeeee eeee e 888-eM eeeeee. Mee eeeeee eee eeeeeeeeeee eeee e eeeeee eeee eee eeeeee eeee eeeee. MeMe (8.88 e, 88 eeee) eee eeeeeee (8.8 e, 88 eeee) eeee eeeee eeeee e eeeeeee eee eee eeeeeee eee eeeeeeeeee eeeeeee eee eeeeee eeeee eee eeeeeee eee eeeee eeeeee (888 °M). Mee eeeee MMe8 eeeeeeeee eee eee eeeeeee eeeeee eeeeeeeeeee eee eeeeee. Meeee eee eeeeeee eee eeee eeeeeeee eee 8 e, ee eee eeeeee eee eeeeeeee ee MM; eeeee: 88% [88% 8-eeeeeeeeeeeeeeeeeee (‌8‌), 8% 8-eeeeeeeeeeeeeeeeeee].

References