Chlorination of  2,5-DMA to obtain DOC is described in PiHKAL (#64). Use is being made of liquid chlorine. In order to avoid this one also could use a second pathway as mentioned by doc himself.  I've been thinking how to do this and my suggestion is to start with the incorporation of a nitro-group on the 4-position and then convert it to an N=N, prior to the chlorination. Do you bees have any clue what the expected yields might be and will this reaction give one major product and no isomers? Is the acetylation of the 2,5-DMA, as suggested, necessary?

Waste off time,  drip mutaric acid on KMnO4, cool the gass with dryice or just bubble the Cl2 gas true the acetic acid. Not that hard to doo. Sandmeyer sucks.
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2,5-dma -> DOC gos in 80-90% on a 10g scale (keep it cold)
by the way rhod's links looks greath.

There are MUCH better methods available at my page:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/nxs.txt

https://www.thevespiary.org/rhodium/Rhodium/chemistry/2c-c.pdf

For smallscale synths:If you have access to liquid nitrogen, you could make some chlorine (see Vogel) & freeze the resulting gas directly in a small schlenk-type vessel. Measuring out how much chlorine you need is relatively easy (the chlorine takes some time to melt/evaporate)

Other alternative is using N-chlorosuccinimide in DCM, see rhodiums page.

BTW: Chlorination sucks. SWIM ended up with about 20-30% unchlorinated/junk amine (both routes, the direct chlorination being a little bit cleaner).

I know Rhodium. Most of your work posted on the net is present in my kitchen, hehe. I will save my DMA for another dinner...Thanks for the advice!