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⚗️ Organic Synthesis · Method

Catalytic Hydrogenation

Catalytic reduction of unsaturated bonds
🎯 Difficulty ★★☆ Medium Duration About 2–4 h 🎯 Use Reduce unsaturated bonds
📖 Principle
Hydrogen is activated on Pd/C or Raney Ni and adds across double bonds or reduces nitro groups.
Below are 5 steps. Open each to see how to do it and add products to your shared list.

📋 Workflow

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1

Charge & solvent

20 min
Dissolve substrate in solvent, add catalyst, transfer to hydrogenation vessel.
💡 Tip Use methanol/ethanol/ethyl acetate for easy removal.
⚠️ Caution Catalyst loading 5–10% of substrate; excess is hazardous.
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2

Purge with hydrogen

15 min
Replace air with nitrogen, then hydrogen, repeating 3 times.
💡 Tip Purge thoroughly; residual air with hydrogen is dangerous.
⚠️ Caution No open flame; hydrogen leakage is explosive.
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3

Pressurized reaction

1–3 h
Set hydrogen pressure, stir, and monitor by TLC.
💡 Tip Typical pressure 1–5 atm, adjusted by substrate activity.
⚠️ Caution Use dedicated high-pressure hydrogenation equipment.
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4

Filter off catalyst

20 min
Filter through celite to remove catalyst, wash the cake with solvent.
💡 Tip Remove catalyst completely; residue affects downstream.
⚠️ Caution Keep the Pd-containing cake wet to prevent spontaneous ignition.
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5

Concentrate & purify

40 min
Concentrate by rotary evaporation, purify by column or recrystallization.
💡 Tip Reduced products may oxidize; process promptly after concentration.
⚠️ Caution Keep rotary evaporation temperature low to avoid decomposition.
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⚠️ 5 Common Beginner Mistakes

  • Catalyst poisoning: sulfur/phosphorus impurities in substrate
  • Incomplete hydrogen purge: explosion risk
  • Over-reduction: excessive pressure or time
  • Catalyst residue: incomplete filtration
  • Product decomposition: high concentration temperature

❓ FAQ

+Why is hydrogenation slow?
Possible catalyst poisoning or low activity; change catalyst, increase pressure or temperature.
+How to avoid over-reduction?
Control pressure and time, monitor closely by TLC, stop when target reached.
+How to handle Pd/C safely?
Keep wet, away from solvent vapors, collect and dispose of the cake properly.

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Data authenticity: Product categories from JW Supply Chain standard taxonomy; method→step→product connected. Last updated: 2026-08-23 · v3.0