O-Xylene → Pyridine, 2,3,5-trichloro-

HRID 1004753Notes

Reaction equation

HRID 1004753 reaction equation
C1(C)C(C)=CC=CC=1.[Cl:9][C:10]1[C:15]([Cl:16])=[CH:14][C:13]([Cl:17])=[C:12](Cl)[N:11]=1.[OH-].[Na+].[OH-].C[N+](C)(C)C>[Zn].O>[Cl:9][C:10]1[C:15]([Cl:16])=[CH:14][C:13]([Cl:17])=[CH:12][N:11]=1

Participants

7

Reactant 4

HCID 7237O-XyleneHCID 14798Sodium HydroxideHCID 169902,3,5,6-TetrachloropyridineHCID 60966Tetramethylammonium hydroxide

Product 1

HCID 27666Pyridine, 2,3,5-trichloro-

Reagents, catalysts & solvents 2

HCID 23994ZincCatalyst2×HCID 962WaterSolvent

Conditions

Temperature
50 °C

Procedure

A 3000 mL, four neck round bottom flask was equipped with a mechanical stirrer, thermometer, reflux condenser, and an opening for the addition of zinc dust. The flask was charged with ortho-xylene (630.4 g, 725 mL) followed by the addition of 2,3,5,6-tetrachloropyridine (525 g, 2.42 mole). Agitation was started and water (775.1 g, 775 mL), 50% NaOH (1162.7 g, 765 mL), and 25% tetramethylammonium hydroxide (5.2 g) were added to the flask. The reaction mixture was heated to 50° C. and zinc dust (195.0 g, 2.98 mole) was added, in equal portions, over a 5-hour period while holding the temperature between 55-60° C. The reaction mixture was then heated at 55-60° C. for an additional 5 hours. After the reaction, the layers were allowed to separate and the top layer (organics) was filtered. Hydrochloric acid (32%, 750.2 g) was added to the bottom layer which was then heated under reflux for 5 hours to convert unreacted zinc to zinc hydroxide (the zinc hydroxide can subsequently be isolated by filtration for recycle value). Organics present in the bottom layer were removed by steam distillation during this time using a Dean-Stark trap, and added to the organics layer. Fractional distillation of the organics layer gave an isolated yield of 2,3,5-trichloropyridine of 65%.

Workup

  1. customA 3000 mL, four neck round bottom flask was equipped with a mechanical stirrer
  2. temperaturethermometer, reflux condenser
  3. custombetween 55-60° C
  4. temperatureThe reaction mixture was then heated at 55-60° C. for an additional 5 hours
  5. customAfter the reaction
  6. customto separate
  7. filtrationthe top layer (organics) was filtered
  8. additionHydrochloric acid (32%, 750.2 g) was added to the bottom layer which
  9. temperaturewas then heated
  10. temperatureunder reflux for 5 hours
  11. customcan subsequently be isolated by filtration for recycle value)
  12. customOrganics present in the bottom layer were removed by steam distillation during this time
  13. additionadded to the organics layer
  14. distillationFractional distillation of the organics layer

Sources & evidence

ORD record
ord-d9dc1a9cde4a42f1b8490f97ed8e6daf
Source dataset
uspto-grants-2000_04
Patent number
US06051714

Reaction notes

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