# Synthesis of active chemical manganese dioxide (CMD) for primary alcohol oxidation

This paper1 uses chemical manganese dioxide (CMD) instead of activated manganese dioxide for mild alcohol oxidation. I'm looking for a route on how to synthesize active CMD. Could this work?

$$\ce{Mn2O7 + 3MnO → 5MnO2}$$ $$\ce{2KMnO4 + 3MnSO4 + 2H2O→ 5MnO2 + K2SO4 + 2H2SO4}$$

How to make chemically pure $$\ce{MnO2}$$ active for oxidation reactions?

Reference

1. Lulinski, Piotr et al. “Chemical Manganese Dioxide (CMD): its application to the oxidative iodination of benzene, halobenzenes and some deactivated arenes.” Molecules (Basel, Switzerland) vol. 9,7 595-601. 30 Jun. 2004, doi:10.3390/90700595
• This preparation of active MnO2 from activated carbon and KMnO4 by Carpino (doi.org/10.1021/jo00836a091) may be of use. Jul 22, 2021 at 15:50
• Pyrolysis of Manganese carbonate at around 410C gives a very active form of MnO2 for use in oxidations Jul 22, 2021 at 16:08
• @Waylander that's convenient, I have access to a lot of manganese sulfate, but building something that could hold 410C for 6 hours would be a challenge. Jul 22, 2021 at 17:38
• My research centre used to have a muffle oven set up at around that temperature for drying mol. sieves and I used that. Jul 22, 2021 at 21:29
• Do not involve Mn2O7. It is a highly reactive and a dangerous oxidizer. It can violently explode and you won't have any control of the reaction. With that being said, check out this paper from 1968: pubs.acs.org/doi/abs/10.1021/jo01258a106 Jul 23, 2021 at 5:06

Your question suggests you did not access Leo Paquette's Encyclopedia of Organic Reagents (14 volumes, some schools have access to the electronic version eEROS), or its one-volume siblings by topic, e.g., Oxidizing and Reducing Agents (this one by Burke and Dannheiser). These resources cover physical / chemical properties of frequently used reagents and briefly showcases a selection of typical applications.

Citing the entry about $$\ce{MnO2}$$ of the former source, one of the of early hints preceding the protocols to prepare $$\ce{MnO2}$$ states for example

«It is worthy of note that the percentage water content strongly influences both the oxidizing power and the selectivity (oxidation of multifunctional molecules) of active $$\ce{MnO2}$$. Thus it is well known that the wet material (40–60% $$\ce{H2O}$$) obtained after filtration must be activated by drying (heating to $$\pu{100–130 ^\circ{}C}$$ for $$\pu{12–24 h}$$ or, better, at $$\pu{125 ^\circ{}C}$$ for $$\pu{52 h}$$). Indeed, an excess of water decreases the oxidation power since, according to the triphasic mechanism generally postulated, it would prevent the adsorption of the substrate to the oxidatively active polar site on the surface of $$\ce{MnO2}$$

The first of the six protocols presented is the basic one by Attenburrow (beside protocols under acidic conditions, by pyrolysis, coating silica gel with active / activated $$\ce{MnO2}$$, etc.) and reads as

«A solution of $$\ce{MnSO4 ⋅ 4 H2O}$$ ($$\pu{110 g}$$) in $$\ce{H2O}$$ ($$\pu{1.5 L}$$) and a solution of $$\ce{NaOH}$$ (40%; $$\pu{1.17 L}$$) were added simultaneously during $$\pu{1 h}$$ to a hot stirred solution of $$\ce{KMnO4}$$ ($$\pu{960 g}$$) in $$\ce{H2O}$$ ($$\pu{6 L}$$). $$\ce{MnO2}$$ precipitated soon after as a fine brown solid. Stirring was continued for an additional hour and the solid was then collected with a centrifuge and washed with water until the washings were colorless. The solid was dried in an oven at $$\pu{100–120 ^\circ{}C}$$ and ground to a fine powder ($$\pu{960 g}$$) before use.»

Probe which of the protocols works well enough for the application in question. Since eEROS points to the primary literature which you may combine in a subsequent search in Reaxys, Science of Synthesis, SciFinder etc., you equally may see which of them are applied on substrates similar to yours.

References

Cahiez G.; Alami, M.; Taylor R. J. K.; Reid, M.; Foot, J. S.; Fader L.; Sikervar V.; Pabba, J. Manganese Dioxide in Encyclopedia of Reagents for Organic Synthesis; doi 10.1002/047084289X.rm021.pub4.

Attenburrow, J.; Cameron, A. F. B.; Chapman, J. H.; Evans, R. M.; Hems, B. A.; Jansen, A. B. A.; Walker, T.. 194. A synthesis of vitamin A from cyclohexanone. J. Chem. Soc. 1952, 1094-1111; doi 10.1039/JR9520001094.

I assume you are looking for activated manganese dioxide (AMD). Apart from the Attenburrow process mentioned in @Buttonwood's answer ($$\ce{MnSO4 + KMnO4 + NaOH}$$), I found three other process that might suit your need (I noticed OP has loads of $$\ce{MnSO4}$$. So, the aforementioned process will work. The processes mentioned in this answer doesn't involve $$\ce{MnSO4}$$ so it can work as alternatives):

1. Rheological phase reaction method from manganese benzoate and $$\ce{KMnO4}$$ characterized by chemical titration (Yuan et.al., 2003)
2. Potassium permanganate and manganese acetate, via a simple alternate drop-feeding method (Han et.al., 2010)
3. Using decolorizing/activated charcoal and aqueous potassium permanganate to precipitate a brown-black powder presumably manganese dioxide mixed with carbon which can be separated using Buchner funnel (Carpino, 1970)
• The Attenburrow protocol only uses $\ce{MnSO4}$, water, $\ce{NaOH}$, and $\ce{KMnO4}$. Reading the entry by Cahiez et al. just again, none of the other five protocols adds sulfuric acid. Even the second method Preparation of Active $\ce{MnO2}$ from $\ce{KMnO4}$ under Acidic Conditions. only reads as «Active $\ce{MnO2}$ was made by mixing hot solutions of $\ce{MnSO4}$ and $\ce{KMnO4}$, maintaining a slight excess of the latter for several hours, washing the product thoroughly with water and drying at $\pu{110–120 ^\circ{}C}$.» Thus, your $+ \ce{H2SO4}$ might be a misunderstanding. Jul 23, 2021 at 21:08
• @Buttonwood Oops, I wrote H2SO4 instead of KMnO4. Fixed it. Jul 24, 2021 at 1:44