Making diethyl 2,5-dianilino-terephthalate (sort of)

I added "sort of" to the title because, after doing the next reaction, the product I got seemed to be mostly, if not completely, dihydroquinacridone. The small amount of the terephthalate present in what I made in this video is likely what lowered the melting point (lit. 163°) of the mostly diethyl-2,5-dianilino-3,6-dihydro-terephthalate and gave it the colors you see. The wide range of the melting points of both products further supports this.
Link to patent: patents.google...
Link to 1914 German paper detailing a bunch of stuff related to condensing diethylsuccinoylsuccinate with ammonia and primary amines: chemistry-euro...
On page 295 is where the m.p. of the dihydroterephthalate is said to be 163°, on pages 300-301 is where the m.p. of the terephthalate is said to be 143°. Today, Feb. 1, I'm doing the synthesis from page 295 because, after making quinacridone (working on one more test, then editing the footage after I wasted like 2 days trying to squeeze out more product from the reaction mixture), I want more to work with, so I need more of the precursor first. The yield in this paper's procedure is ~79% after recrystallizing the product, but it uses significantly proportionately less aniline than what was used in this video, so I don't mind. The quinacridone synthesis video will come out first.
Mechanism Description:
There's a nucleophilic attack of one of DESS's carbonyl carbons by aniline's nitrogen's free electron pair, and a free electron pair attacks a free proton. There's a proton transfer from the positively charged ammonium to the adjacent hydroxyl's oxygen - it's also possible that the proton transfer occurs from an aniline hydrochloride molecule, and one of the ammonium protons gets spit off. The exchange of protons (and chloride ions where it makes sense) is made significantly more favorable by the solubility of aniline hydrochloride in the reaction mixture. A water molecule leaves, and the nitrogen's free electron pair moves to make a double bond between it and carbon. This protonated imine intermediate would typically spit off a proton, accepted by a free aniline molecule, but the ester-adjacent carbon also has an acidic proton as well, and imine's are only stable at fairly specific temperatures, so an imine-enamine tautomerization occurs. This whole sequence happens again, and we end up with diethyl 2,5-dianilino-3,6-terephthalate. Diethyl 2,5-dianilino-3,6-terephthalate is readily oxidatively hydrogenated by the oxygen in the air to diethyl 2,5-dianilino-terephthalate. I have no idea what the mechanism is for this, but I do know that it involves radicals.
General aldehyde/ketone-amine reaction to form imines: chem.libretext...
Notes:
The colors of the two crops of crystals are obviously very different. The first is orange and the second is red. The literature melting point for the dihydro compound is reported to be 163°, so I think the first or both crops are a mixture of both compounds. Because the dihydro compound has a slightly higher molar mass, the yield is probably slightly under 91%.
The 34.74g aniline sulfate recovery is either a 40.51% (if it's 1:1) or 54.48% (if it's 2:1) recovery of the unreacted aniline. The second and third crops that I recovered are drying in my desiccator.

[@dimaminiailo3723]

nice colours. I would've probably recrystallized it once more for cosmetic purposes

[@IgorMuravyov-o5r]

Literature References would be nice of you to provide. Could you please do that if possible to add? Appreciate it!

[@IgorMuravyov-o5r]

Look up aminothiophenes, these things are quite useful and easy to make. But, aminothiophen without EWG decomposes if not SnCl4-complexed. Hydrochloride itself is stable if cause.

[@saintmotel7813]

3:22, can you drink it?

[@barfbot]

not bad at all for a toluene wash

[@chemistryofquestionablequa6252]

Is there a specific use for this you have in mind, or is it just a cool symmetrical molecule?

[@Cairlos001]

Hint in the previous video Making diethylsuccinoylsuccinate - the Claisen condensation

[@chemistryofquestionablequa6252]

@Cairlos001 thanks, I just rewatched that one.

[@IgorMuravyov-o5r]

Steam distill the mixture of aq. aniline, look in the Organic Synthesis procedure for aniline oreparation. My recollection they had it there or..may be Vogel book. Do not mess with this coloured crap you have got without some reducing agent be that acitic medium or basic, iron in acid is a primitive stuff and works or sodium sulfides in basic solution or Na2S2O4, thiourea disulfide is less economical. Na2s2o4 is a very useful reductunt for substituted aromatic amines and reduces all that brounish-blackish tar. The most convenient to reducing agent for these procedures.