[curiouscat]

Is there a way to avoid getting an MnO2 ppt when using KMnO4 as an oxidizing agent? Preferably some strategy that does not  involve a highly acidic pH.

I had read somewhere that at pH above 12 the mangnate ion would get preferentially formed and I was hoping this might prevent the MnO2 ppt but I couldn't get this to happen.

Any other ways to prevent or solubalize MnO2 solids in situ?

[Hunter2]

At pH higher then 4 MnO₂ will be formed in any case, this cannot be prevented. In lower pH Manganese-II is built up and MnO₂ get dissolved. Right at very high pH Manganate MnO₄^2- is also formed, but still some manganese dioxide.
Some MnO₂ is created from the manganate with an reaction on the glass wall of the flask or beaker at high pH. Probably some catalytic effect.

2 MnO₄^2- + 2 H₂O => 2 MnO₂ + 4 OH^- + O₂

[curiouscat]

At pH higher then 4 MnO₂ will be formed in any case, this cannot be prevented. In lower pH Manganese-II is built up and MnO₂ get dissolved. Right at very high pH Manganate MnO₄^2- is also formed, but still some manganese dioxide.
Some MnO₂ is created from the manganate with an reaction on the glass wall of the flask or beaker at high pH. Probably some catalytic effect.

2 MnO₄^2- + 2 H₂O => 2 MnO₂ + 4 OH^- + O₂

So in theory, asides of the catalytic glass wall side reactions, it is indeed possible to get the soluble manganate ion entirely without any MnO2?

[Hunter2]

Yes you can obtain the manganate ion, but if this is free of manganese dioxide I don't know. We use an application in an alkaline Permanganate etch bath for cleaning the holes of printed circuit boards. The used solution will be recycled by electrolysis. 

MnO₄^2- => MnO₄^- + e^-