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Nitration and Column Chromatography

Nitration and Column Chromatography. Nitration Reaction. Isolation of crude product Recrystallization: First and Second Crop Impure minor product. Chromatography. Review main purpose, strengths, weaknesses: Gas Chromatography Thin Layer Chromatography Why another technique?.

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Nitration and Column Chromatography

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  1. Nitration and Column Chromatography

  2. Nitration Reaction • Isolation of crude product • Recrystallization: First and Second Crop • Impure minor product

  3. Chromatography • Review main purpose, strengths, weaknesses: • Gas Chromatography • Thin Layer Chromatography • Why another technique?

  4. Column Chromatography • Similar to TLC in separation • Preparative process • 0.1g to 5 g scale • Purify small quantities of liquids/solids (contrast distillation and recrystallization)

  5. Mobile phase: eluent similar to TLC • Stationary phase: silica gel similar to TLC • Column is upside down from TLC, so a larger Rf for a compound means it comes out ____

  6. Practical Considerations • Preparing the column • Loading the sample • Choosing the solvent • Separation capacity

  7. Practical Considerations • Preparing the column • Loading the sample • Choosing the solvent • Separation capacity

  8. Practical Considerations • Preparing the column • Loading the sample • Choosing the solvent • Separation capacity Most common: Hexane/ethyl acetate CH2Cl2/methanol

  9. Practical Considerations • Preparing the column • Loading the sample • Choosing the solvent • Separation capacity • Effect of diameter • Effect of length • Effect of Silica gel grade

  10. Flash Chromatography • Faster separation • Tighter separations

  11. HPLC

  12. Review of Techniques • Purification • Extraction • Recrystallization • Distillation • Column chromatography • Purity analysis • Elemental analysis • Mp, bp • GC • TLC • Proton NMR • Identification • MS • IR • NMR • mp, bp • GC • TLC • JOC requires • IDENTITY: 1H NMR and 13C NMR plus either HRMS or EA • PURITY: 1H NMR or EA or GC or HPLC

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