Hi s3v3n,
I did try this using benzaldehyde, nitroethane, and n-butylamine. As a template, I used 3,4-DMA from PIHKAL. Instead of the veratraldehyde and n-amylamine, I used benzaldehyde and n-butylamine, and adjusted the amounts accordingly.
The RM seems unchanged after a month. No solids have precipitated at all.
This was my last effort in a line of unsuccessful reactions with this nitroethane:
Nipron ®™ fuel enrichment additive cas 79-24-3 Pure nitroethane based, 100 ml.
This was supposed to be >98% nitroethane (NE). I didn't have any way to definitively check it, so it could be something other than NE or have high water content. Was expensive too - $125 for 100mL delivered.
I think this reaction (and I thought it was a Knovenagle reaction, not a Henry reaction!) would work, but there may be something about the unsubstituted benzaldehyde that requires different reaction conditions.