Some general remarks on dialkylated tryptamines:
The phrase “gradient of ethyl acetate:methanol” I interpret to mean starting with the less polar pure methanol and slowly increasing the ratio of ethyl acetate added, finishing with pure ethyl acetate. Is this correct?
No, gradient must less polar to polar, MeOH is way more polar than ethyl acetate.
looking for a spot with a smaller Rf than that of the starting tryptamine,
No it must be of a higher Rf, tryptamine is way more polar than dialkylated tryptamines
Far less important, does the PDMAB work through forming a highly conjugated imine with the tryptamine?
No, it's an indole-2 (or indole-3 if free) aromatic substitution.
Has anyone ever characterized the formed colored products?
Not as far as I know. But one main degradation product is skatole (3-methyl-indole), it gives tryptamines the characteristic fecal smell. It is of low polarity = high Rf.
Sure it will improve the process of obtaining a pure extracted natural product!
also look here:
"N,N-dimethyl tryptamine 2a
1 g of alpha-chloromethyl-gramine HCl is added to a suspension of 2,5 g of NaBH4 in 75 mL of diglyme at 55°C with stirring. The slurry is warmed to 85-90°C and is kept at that temperature for 48h. The yellow coloration has disappeared. After 24h the mixture is cooled and poured on some ice. This is extracted with ethyl acetate and then the solvent is removed. The remaining oil has got a scatole stench and the TLC show two spot with Rf equal respectively to authentic sample of scatole and of DMT. These two products are separated by column chromatography (silice-celite 1/1). The scatole is eluted first with benzene and is identified by its mp and its picrate salt. The DMT is eluted with methanol (270 mg, 37%). After one recrystalisation with hexane, the product melt at 45°C, this mp is inchanged when authentic sample is mixed with it. The DMT is confirmed by its picrate salt, mp 166°C, and by its UV and IR spectra."
it's from:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/dmt.chloromethylgramine.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/dmt.chloromethylgramine.html)