If you don't have seed crystals you'd probably be better of scraping the vial
Just dont clean the glassware it is supposed to crystallize in like you were your mother, some waterstains are enough to get it going
Experiment showed that it is not about the absolut maximum temperature which should not be exceeded but the time. Quick heating to 80-90°C in the microwave does not induce orange color but if it is kept very short, just heating up and done it stays greenish yellow as it should and....
Yes and. It was discovered that when doing it in the microwave it is frigging easy to determine the right point to stop because the greenish-yellow clear solution turns turbid, the greenish has vanished and its yellow alone. Thats the moment to slowly put it in some icecold waterbath and crystals crash out instantly.
Thats what has happened by now and we will see if the filtrate later will yield further crops. Now in the fridge to get all first crop crystals to form, then filtration and on for more. Will there be more? Thats the question which will decide upon the fate of this way.
If Elektro`S and Gusie are right and this step by step harvesting works, it will be the most simple reaction ever. The actual reaction time in the Micro was less then 2 minutes. There are good chances IMHO the speed of the reaction prevented any catalyst degradation.
Benzaldehyde and Nitro were fresh distilled. This seems a must for a clean reaction. Without there were low yields and plenty of problems.