Science of Synthesis

von Angerer, S., Science of Synthesis, (2005) 26, 51.

The discovery of pyridinium chlorochromate[‌91‌] was an important step in the application of chromium-based oxidizing agents. It is readily and safely prepared by the addition of pyridine to a solution of chromium(VI) oxide in 6 M hydrochloric acid and it can be stored for extended periods.[‌91‌] It has been widely used in its original form to oxidize secondary alcohols to ketones, e.g. ‌33‌,[‌92‌] but can also be modified in several ways (‌Table 1‌). The pyridinium ion can be replaced by other protonated heterocycles or ammonium ions.[‌32‌] Complexation of the ammonium ion by 18-crown-6 renders these reagents soluble in organic solvents (‌Table 1‌, entry 2).[‌31‌] Generally, halogenated organic solvents such as chloroform or dichloromethane are used, but these oxidation reactions can also be performed without any solvent (entries 8–10).[‌42‌,‌43‌,‌93‌]

Meee ee eeeee eeeeeeee eee eeee eeeee eeee eeee eeee eeeeeeee ee e eeeee eeeeeee eeee ee eeeeeee (eeeeeee 8, 8, 8 eee 8),[‌88‌,‌88‌] eeeeee eee (eeeee 8),[‌88‌] ee eeeeeeeeeeeeeee M 88 (eeeee 8).[‌88‌] Me eeeeeee ee eee eeeeeeeeee ee eeeeeeeee eeeeeee eeeeeeee eeee eee eeeeeeeeeeeee eeeeeee ee eeeeeeeee eeee eeeeeeeeee eeeeeeeeeeeeee ee eeeeeee ee eeeeeeeeeeee ee eee eeeeeeeeee ee eeeeeee eeee eeeeeee (‌88‌) (‌Meeeee 88‌).[‌88‌] Mee eeeee ee eeeeeeee eee eeeeeeee eeeeeeeeee ee eeeee ee ‌Meeee 8‌.

‌Meeee 8‌ Meeeeeeee ee Meeeeeeee Meeeeeee ee Meeeeee eeee Meeeeeeeeeeeeee[88,88,88,88,88-88,88,88]

‌Meeeee 88‌ Meeeeeeee ee Meeeeee ee Meeeeee ee Meeeeeeeee Meeeeeeeeeeeee ee Meeeeee[‌88‌]

Mee eeeeeeeee ee eeeeeeee eeee eeeeeeee(MM) eeeee ee eeeeeeeeeee eeee eeeeeeeeee eeeeeeee eeeee, eeeee eee eee ee eeeee-eeeeeeee eeeeeeeee, eee eeeee ee eeeeeeeee eeeeeee.[‌88‌] Me eeeeeee ee eee eeeeeeeee ee eeeeeeee-8-eeee ee eee eeeeeeeeeeeee eeeee ‌88‌ (‌Meeeee 88‌).[‌88‌] Meeeee eeee eeeee eeeeeeeeee eeeeeeee eeeeeeeee eeee ee eeeeeeeeee eeee eee ee eeeeee eeee eeeeeeeeeeeeee eee ee eeee eee eeeeeeeeee ee eeeee eeeeeee.[‌88‌]

‌Meeeee 88‌ Meeeeeeee ee Meeeeeee-8-eeee ee Meeeeeee-8-eeeee eeee Meeeeeee(MM) Meeee ee eee Meeeeeee ee Meeeeeeeeeeeeeeeee Meeeeeee[‌88‌]

Meee eeeeeeeee ee eeeeeeee-eeeee eeeeee eee ee eeeeeeeee eeee eee eeeeeee ee eeeeeeee eeee eeeeeee ee eeeeee eee eee ee eee eeeeee eeeeeeee eeeeeeeeee. Meee ee eeeeeeeeeee ee eee eee ee eeeeeee eeeeeeee eeeeeeee ee e eeeeeee ee eeeeeee eee eeeeee eee. M eeeeeee ee eeeeeee eee eeeeeeeee ee eeeeeeeeeee eeee eeee eeeeeee ee eeeeeeeee eeeee, e.e. eeeeeeeee ee 8-eeeeeeeeeeeeeeeeee (‌88‌) (‌Meeeee 88‌).[‌88‌]

‌Meeeee 88‌ Meeeeeeeee ee 8-Meeeeeeeeeeeeeeee eeee 8-Meeeeeeeeeeeeeeeee ee Meeeeee Meeeeeee ee Meeee Meeeeee[‌88‌]

Meeee eeeee eee eeee eeeeeeeeeee ee eee eee ee eeeeeeeeeeeeeee eee ee eee eeeeeee ee eee eeeeeeee eee eeeee eeeeeee eeeeeeeeee, ee eeeeeeeeeee eeeeeee 8,8-eeeeeeeeeeeeeeeeee eeeeeeeeeeeeee eee eeee eeeeeeeee.[‌88‌] Me ee eeeeeee eeeeeeee eeee eeeeeeee(MM) eeeee ee eeeeeeee ee eeeeeee eeeeeeeeeeee eeee eee 8,8-eeeeeeeeeeeeeeee ee eee eeeee eeeee ee 8:8:8 eee ee ee eeeeeee ee eeee eeeeeee eeeeeeee.

Meeeeeeeeeee Meeeeeeee

Meeeeeeee ee Meeeeeee ee Meeeeee ‌88‌: Meeeeeeee ee 8-Meeeeeeeeeeeeeeeeee (‌Meeee 8‌, Meeee 8); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeee(MM) eeeee eeee eeeeeeeee eee eeeeeeeeeee eeeeee eee ee eeeeeeeeee ee e eeeee eeeeeeeeee.

Me e eeee ee MeM8 (88 e, 8.8 eee) ee 8 M MMe (88 eM) eee eeeee, eeeeee 8 eee ee 8–8°M, eeeeeeee-8-eeeeeeeeee eeee (88.8 e, 8.8 eee). Mee eeeeeee eee eeeeeee ee ee eeeee e eeeeee-eeeeee eeeee eeeeee. Meeeeee ee 88°M eeee e eeee. Meeeeee (88 e) eee eeee eeeee ee eee eeee eeee eeeeeeee ee 88°M. Meeee eeeeeeeeeee ee e eeeeee eeeeeeeeee, eee eeeeee eeeee eee eeeee ee eeeee ee ee eee 8 e. Mee eeeeeeeee eeeeeee eee ee eeee eee eeeeeee eeeee eeeee eeeeee ee eee eeee eeeeeee eeeeee eee eeeeeeee.

Meeeeeeeeeeeeeeee eeeeeeeeeeeeee ee eeeeeee (8 e, 8 eeee) eee eeeee ee e eeee ee 8-eeeeeeeeeeeeeeeeee (888 ee, 8.88 eeee) ee MM8Me8 (88 eM). Meeee eeeeeeee eee 8 e , eee eeeee eee eeeeeeee eee eeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeeee eeeeeeeee eeee eeeeeeeeeeee. Mee eeeeeee eee eeeeee eeeeeee e eeeee eeeeee eee eee (eeeeeeeee eeeee/Me8M 8:8) ee eeee eeee eeeeeee; eeeee: 88%.

Meeeeeeee ee Meeeeeee ee Meeeeee ‌88‌ eeeee Meeeeee-Meee Meeeeeeeee: Meeeeeeee ee Meeeeeeeeeeeee (‌Meeee 8‌, Meeee 8); Meeeeee Meeeeeeee:[‌88‌]

MMM (8–88 eeee) eee eeeee ee eeeeeeeeeeeee (8 eeee) ee e eeeeee. Mee eeeeeeee eeeeeeeee eeee eeeeeeeee eeeee eee eeee eeeeee eee 888 eee ee ee eeeeeee eee eeeeeee eeeeeeeee. Mee eeeeeeee ee eee eeeeeeee eee eeeeeeeee ee MMM (eeeeee eee, eeeeee/Me8M 8:8). Meee eeeeeeeeee ee eee eeeeeeee 88% MMe (88 eM) eee eeeee eee eee eeeeeee eee eeeeeeeee eeee Me8M (8 × 88 eM). Mee eeeeeee eeeee eee eeeeeeeee eee eeeee (MeMM8). Meeeeeeeeee ee eee eeeeeee eeee eee eeeeeee; eeeee: 88%.

Meeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeee(MM) eeeee eeee eeeeeeeee eee eeeeeeeeeee eeeeee eee ee eeeeeeeeee ee e eeeee eeeeeeeeee.

Me e eeee ee MeM8 (8 e, 88 eeee) ee 8 M MMe (88 eM) eee eeeee eeeeeeee (8.88 e, 88 eeee) eeeeee 88 eee ee 88°M. Mee eeeeeee eee eeee ee 88°M eeeee e eeeeee-eeeeee eeeee eeeeee. Meeeeeeee ee 88°M eeee e eeee. Meeeeee (88 e) eee eeee eeeee ee eee eeee eeee eeeeeeee ee 88°M. Meeee eeeeeeeeeee ee e eeeeee eeeeeeeeee, eee eeeeee eeeee eee eeeee ee eeeee eee 8 e ee ee. Mee eeeeeeeee eeeeeeeee eeeeeee eeeee ee eeee eee eeeeeee eeeee eeeee eeeeee ee eee eeee eeeeeee eeeeee eee eeeeeeee.

Mee MMM eeeeeeee ee eeeeeee (8.8 e, 8.8 eeee) eee eeeee ee e eeeee eeeeeeeeee e eeee ee eeeeeee (8.88 e, 8.8 eeee) ee eeeeee (88 eM). Meeee eeeeeeee eee 8 e, eee eeeee eee eeeeeee ee eeeeeeeeee eee eeeeee eeee Me8M (8 × 88 eM). Mee eeeeeeee eeeeeeeee eeee eeeeeeeeeeee eee eeeeeeeee ee eeeee ee eeee eee eeeeeee; eeeee: 8.88 e (88%); ee 888°M/88 Meee.

Meeeeeee-8-eeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeee(MM) eeeee eeee eeeeeeeee eee eeeeeeeeeee eeeeee eee ee eeeeeeeeee ee e eeeee eeeeeeeeee.

MeM8 (888 ee, 8.8 eeee) eee MMMMe (88 ee, 8.888 eeee) eeee eeeeeeeee ee eee MM8Me8 (8 eM), eeeeeeee ee eee eeeeeeee eeeeeeee ee eeeeeeee-8-eeee (88 ee, 8 eeee) ee MM8Me8 (8 eM) eee eeeeeee eee 88 e. Meee eeeeeee eee eeeeeeee ee ee 88 eeee, ee eeeeee ee eeeeeeeee eee eeeeeeeee. Mee eeeee eeeeeee eee eeeeeeee eeeeeee e Meeeee eee eee eee eeeeeeeee eeee eeeeeeeeeeee. Mee eeeeeee eee eeeeeeeeee eeee Me8M; eeeeeeeeeeeee eee eeeeeeeeeeee eeee eee eeee eeeee eeeeeeee; eeeee: 88%.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 888.