Troubleshooting synthesis of halazone from dichloramine-T

I was trying to oxidize some [dichloramine-T](https://en.wikipedia.org/wiki/Dichloramine-T) to [halazone](https://en.wikipedia.org/wiki/Halazone). It should be easy enough since dichloramine-T has a free methyl group *para* to the *para*-sulfomyldichloro group. I followed a published procedure [[1](https://doi.org/10.1007/BF00810903)], but got very different results.



> 
> By oxidation of easily available dichloramine-T (**3**) with $\ce{KMnO4}$ in mild alkaline medium, we have been able to obtain as high as $95\,\%$ halazone containing $18-20\,\%$ chlorine. In this procedure, the sodium salt of halazone (**4**) is formed in the first step which, after hydrolysis with dilute $\ce{AcOH},$ gives a white crystalline compound with a chlorine odor, melting at $\pu{196 °C}$ with decomposition.
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> [![Dichloramine-T to sodium salt of halazone](https://i.stack.imgur.com/9W21c.png)](https://i.stack.imgur.com/9W21c.png)
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> ### Experimental
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> In a $\pu{250 ml}$ flask, $\ce{KMnO4}$ $(\pu{2.9 g})$ was placed and dissolved in water $(\pu{150 ml}).$ Dichloramine-T $(\pu{2.5 g})$ and $\ce{Na2CO3}$ $(\pu{5 g})$ were mixed and added to the flask and
> stirred for $\pu{5 min}.$ The reaction mixture was refluxed on a steam bath until the dark violet color disappeared $(\pu{2 h}).$ The mixture was then cooled at $\pu{25 °C}$ and filtered. A dark brown precipitate was separated $(\ce{MnO2}).$ The filtrate was yellowish with a chlorine odor which was concentrated and later neutralized with $\ce{AcOH}$ $(50\,\%).$
> While neutralizing the solution, a vigorous reaction occurred and a white substance precipitated which was filtered and dried. Yield $95\,\%,$ m.p. $\pu{195-196 °C}.$ This compound was identified as *N*,*N*-dichlorosulfamoylbenzoic acid by direct comparison (ir, mass, m.m.p.) with an authentic sample.
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My two main problems are:


1. I can't precipitate the product out of the solution as mentioned. My mother liquor stays colorless and no precipitation occurs upon acidification.
2. I can't separate the $\ce{MnO2}$ particles from the solution using normal methods like filter papers/cloth and have to use Hyflo® Super Cel® filter aid each and every time.


I've used chromic acid, chromyl chloride, $\ce{KMnO4},$ $\ce{H2O2}$ all to try and oxidize the compound with no avail. Really need some help with this.


### Reference


1. Saljoughian, M.; Sadeghi, M. T. An improved procedure for the synthesis of *p*-(dichlorosulfamoyl)benzoic acid (halazone). *Monatsh Chem* **1986**, 117 (4), 553–555. DOI: [10.1007/BF00810903](https://doi.org/10.1007/BF00810903).


