Big Breakthrough for Benzo Bees

[Rhodium]

Facile and convenient syntheses of quinones from phenols
F. Minisci, A. Citterio, E. Vismara, F. Fontana, S. DeBernardinis, M. Correale

J. Org. Chem. 54, 728-731 (1989)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/hydroquinone2benzoquinone.h2o2-i2.pdf)


General Procedures for the Oxidation of Hydroquinone to Benzoquinone

(A) H₂O₂ (60%) (10.0 mL, 0.22 mol) was added dropwise with stirring to a solution of Hydroquinone (0.20 mol), I₂ (0.01 mol), and concentrated H₂SO₄ (10 mL) in methanol (600 mL) at room temperature. After 4 h part of the formed quinone crystallized and was collected by filtration. The methanolic solution was poured in 100 mL of water and extracted with ether, and the solvent evaporated to give crude benzoquinone. Yield 97%.

(B) A procedure similar to A, with the only difference that water was used instead of methanol. In this way the benzoquinone directly crystallized from the aqueous solution and was easily separated by simple filtration. Yield 93%.

(C) A procedure similar to A was followed with the difference that 20 mmol of HI was utilized instead of I₂. Yield 95%.

(D) A procedure similar to B was followed with the difference that 20 mmol of HI was utilized instead of I₂. Yield 93%.

(E) The same procedure as in A was used, with the difference that 10 mmol of Br₂ was utilized instead of I₂. Yield 52%.