[URgEnthalpy]

I can't find literally any info about solubility of aminoacids and similar compounds (creatine, taurine) in organic solvents.
I am a little bit confused if the best solubility would be in their isoelectric point, or protonated/ deprotonated form. Would be direct pouring on the powders CH₂Cl₂ better, or making solution in the first place and adjusting right pH is a better solution?

[Babcock_Hall]

I have often worked with amino acids, but I have not seen information on the solubility in in organic solvents.  I suspect that you are correct about the isoelectric point.  Obviously if working with them as BOC-derivatives is a possibility, that might be somewhat easier.  However, my experience is that even BOC-derivatives will partition from ethyl acetate into water if the carboxylic acid group is deprotonated to form a carboxylate.  Were you able to calculate the pI values of the compounds of interest to you?

[wildfyr]

I bet they are all soluble in methanol, DMF and DMSO at all pHs.

[Babcock_Hall]

https://www.tandfonline.com/doi/pdf/10.1080/00021369.1966.10858601
Hayashi K, et al., Agr. Biol. Chem., Vol. 30, No.4, pp. 378-384, 1966
See Table I for data on methanol and ethanol.

[wildfyr]

Dang, I was wrong. This data says to me that there isn't a blanket statement one can make about amino acid solubility, it's a case by case basis. At their isoelectric point they will indeed be most soluble in organics like DCM.

[Babcock_Hall]

One question that has long occurred to me is what is the tautomeric equilibrium for an amino acid in an organic solvent.  I would think that it would be very different from water, but I have never seen data that address this question.