Simple One-Pot Synthesis of NEP (N-Ethylpentedrone)
N-Ethylpentedrone (NEP, 2-(ethylamino)-1-phenylpentan-1-one) is a psychostimulant belonging to the cathinone class. It induces euphoria and increases motor activity. Dosages and duration depend on tolerance to cathinones, ranging from 20 to 60 mg, with effects lasting up to 6 hours.Reagents for NEP Synthesis:
- Valerophenone – 100 mL
- Hydrobromic acid (40-48%) – 160 mL
- Hydrogen peroxide (35%) – ~60 mL
- Ethyl acetate – 300 mL
- Ethylamine – 150 mL
- Isopropyl alcohol (IPA) – 30 mL
- Distilled water (in excess)
- Baking soda (in excess)
- Non-iodized table salt
Equipment:
- 1000 mL beaker
- 20 mL syringe
- Magnetic stirrer with heating
Synthesis of N-Ethylpentedrone:
Stage 1: Synthesis of 2-Bromovalerophenone
1. Add 100 mL of valerophenone to the beaker with a stir bar inside.2. Pour in 100 mL of 40-48% hydrobromic acid.
3. Start stirring.
4. Draw 35% hydrogen peroxide into the syringe and add it slowly in small portions.
5. The mixture will turn red (bromine is released) and heat up.
6. Wait until the bromine reacts (red color disappears).
7. Once bromine stops reacting (red color persists or red vapor is visible above the liquid), stop adding peroxide and stir until the mixture becomes colorless (excess bromine evaporates).
8. Pour in cold water and stir. This cools the reaction and removes excess acid. Use an amount of water based on available space in the reaction vessel.
9. Decant the water or remove it with a syringe (the desired product is the bottom layer).
10. Add a saturated solution of baking soda (use as much as possible without leaving undissolved residue). The volume should match the reaction vessel’s capacity.
11. Stir, separate the soda solution, and repeat the washing with a saturated solution of non-iodized table salt (prepared similarly).
12. Separate from the salt solution, rinse with clean water, and isolate the bottom layer for further use. Yield: ~150 g.
Stage 2: Synthesis of NEP from 2-Bromovalerophenone
1. Add 300 mL of ethyl acetate to the 150 g of 2-bromovalerophenone and stir.2. Add 150 mL of 70% ethylamine and heat the mixture gradually (do not exceed 70°C).
3. Reaction time at optimal temperature (~60°C) is 20-30 minutes, but longer times won’t harm the reaction. If yield is low, extend the time.
4. After 30 minutes, add cold water and stir to remove excess ethylamine.
5. Let the layers separate (the top layer is ethyl acetate containing the product in freebase form).
6. Separate the lower aqueous layer from the upper one. Repeat washing if the ethylamine smell persists.
7. Using a syringe, slowly add hydrobromic acid (or hydrochloric acid) dropwise while stirring. Avoid excessive heating (to prevent ethyl acetate hydrolysis).
8. Continue adding acid until product formation stops (no localized reddening upon stirring) or use pH strips (pH ~3). In this case, 58 mL of 48% HBr was used.
9. Add 60 mL of water and continue stirring with heating until the solution clarifies (all product dissolves in water).
10. Separate the upper ethyl acetate layer (contains impurities) from the aqueous layer (contains dissolved NEP).
11. Mix the aqueous layer with 30 mL of isopropyl alcohol, stir, and let it crystallize. To speed up crystallization, use a shallow Pyrex dish or refrigerate at +5 to +7°C.
12. Within 24 hours (faster in the fridge), crystals will form. For larger crystals, add more water and alcohol (e.g., +60 mL water +15 mL IPA). Maximum yield: ~127 g.
Conclusion
NEP can be synthesized relatively easily without complex equipment. A hot water bath, thick glass bottles, and manual stirring can replace lab tools. The reaction can proceed without heating but will take longer. For fine crystals, filter through uncolored fabric or coffee filters. To recover product without filtration, dissolve large crystals and air-dry to constant weight. Do not discard the mother liquor until maximum yield is achieved.
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