n,n-dimethylpentedrone (DMP)

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M(2BrV) = 241.124 g/mol
M(NH(CH3)2) = 45.085 g/mol
M(DMP fb) = 206.305 g/mol
M(DMP HCl) = 242.765 g/mol

M(HCl) = 36.46 g/mol
M(Na2CO3) = 106 g/mol
M(NaOH) = 39.997 g/mol
M(citric acid monohydrate) = 210.14 g/mol

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n = 10 g / 242.765 g/mol = 0.0412 mol

 1. Add 10g 2BrV to a reaction flask with 25mL EtOAc
 2. Add 5.6g NH(CH3)2 (dimethylamine), i.e., 14g 40% NH(CH3)2 solution with
    vigorous stirring while maintaining temperature below < 65C.
 3. Run the reaction for +12h after the addition of the last drop.
 4. Wash 1x with 50mL saturated NaHCO3 water.
 5. Acidify with 10g citric acid monohydrate.
 6. (Optional:) Wash the extracted aqueous layer with 15mL xylene.
 7. Basify with 13g Na2CO3 (~3 mol eq.) - be careful with the released CO2 gas!
 8. Decant the top freebase layer, discarding the bottom aqueous layer.
 9. Dissolve the freebase layer into a freezer-cold acetone and precipitate
    by acidifying with 1.55g HCl, that is, 4.7g of 33% HCl(aq) until the pH
    reaches 5-6 or the all DMP precipitates out. It is recommended to use cold
    33% HCl(aq). Dilute the acid with cold water/acetone to avoid overshooting
    the pH lowering as this can prevent the DMP HCl product from cystallizing.
10, Filter and wash with cold acetone, repeating this until the product is
    reasonably white. If filtering is not an option due to poor precipitation,
    try freezing the mixture for ~12h in a cold freezer.
11. Dry the DMP crystals in a room with dry air and good ventilation.
12. (Optional): Recrystallize the product (in acetone or EtOH/H2O) to purify

Theoretical yield: 10 g DMP HCl (~0.0412 mol).
Actual yield: ~80%