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Separating stereoisomers

Separating stereoisomers. Difficult to make just one so. . . Make a racemic mixture 50/50 Then separate the enantiomers Chiral chromatography Stereoselective (asymmetric) synthesis Using chiral auxillaries Pure enantiomer combines with non-chiral reactant to form chiral intermediate.

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Separating stereoisomers

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  1. Separating stereoisomers Difficult to make just one so. . . Make a racemic mixture 50/50 Then separate the enantiomers Chiral chromatography Stereoselective (asymmetric) synthesis Using chiral auxillaries Pure enantiomer combines with non-chiral reactant to form chiral intermediate

  2. taxol Originally obtained from Pacific yew tree bark Semi-synthetic process from the needles Now fermentation using plant cell cultures Anticancer drug Prevents cell division

  3. An enantiomer rotates plane-polarized light clockwise • (+) • Rotates it counterclockwise • (-)

  4. Specific rotation = [] • The angle which the light is rotated in degrees = () • The path length of solution the light passes through (l) dm • Concentration of solution (c) in gcm-3 depends on wavelength of light used, temp, and solvent Relies on purity of sample

  5. Extraction of drug • After synthesis of a drug it must be extracted form the reaction mixture • Depends on solubility • Presence of Non-polar, polar, H-bonds • Insoluble solids can be added to ice water • Precipitate can be removed by filtration • Solvent extraction • Shaking aqueous mixture with an immiscible solvent • Separation funnel

  6. purification • Recrystallization • Distillation • Different boiling points • Fractional distillation • similar boiling points • Uses vapor pressure • chromatography

  7. Raoult’s law • Vapor pressure • Pressure exerted by a vapor in equilibrium with its liquid or solid • The contribution of each component of a mixture to the total vapor pressure depends on what the vapor pressure of the pure liquid is and how much is present in the mixture. • PA = XA x PA

  8. Nuclear medicine • Alpha, beta, gamma, proton, neutron, positron emission • Radioactivity is used in the diagnosis and treatment of disease. • Radioactive atoms are incorporated into drugs or biochemical mcs and are injected into the body • Molecules cruise through the body and are watched by a radiation detector

  9. radiotherapy • Treatment of disease (cancer) using radiation • Ionizing radiation can interact directly with the DNA of highly replicating cells or form free radicals • Water HO (hydroxyl radical) • Super dangerous DNA, protein and lipid destroying free radical • External or internal source of radiation

  10. Side effects of radiotherpy • Damages healthy cells in the area of treatment • Temporary • Hair loss • Nausea • Fatigue • Permanent • sterility

  11. Technetium-99m • Most common radioisotope used in medicine • m-refers to metastable state • Long-lived excited nuclear state • Decays to Tc-99 emitting gamma rays • Half-life = 6 hours • Long enough for full body travel • Short enough for minimal damage from radiation • Can be made water soluble • TcO4-

  12. β emitters • Internal radiotherapy • Interact with matter more effectively • Lose energy with a few millimeters in the body • Yttrium-90 • Half-life = 64 hours • Treats liver cancer • Tiny beads are injected into the liver artery—killing tumor cells

  13. Lutetium-177 • Half-life = 6.71 days • β-emitter and γ-emitter • Used for treatment of neuroendocrine cancer • Or imaging

  14. Targeted alpha therapy • - particles • Large • Highly charged • cause great damage to a small area • Cannot penetrate skin • 20 - particles kill one cell • Monoclonal antibodies (same shape) • Target cancer cells • Astatine-211 • Half-life=7.2 hours • Pb-212 • Half-life =10.6 hours

  15. Radioactive radium chloride • Ra-223 •  and γ emitter • Half-life = 11.4 days • Treat bone cancer • The body takes up Ra like Ca killing the cancer cells

  16. Boron-neutron capture therapy • Head and neck cancer • Non-radioactive B-10 is taken in by cancer cells • Its irradiated with a neutron beam • Makes B-11 • Makes an  particle • Kills the cancer

  17. Magnetic resonance imaging • MRI • Uses nuclear magnetic resonance to produce 3-d images of internal organs • Why is the name nuclear missing from MRI? TOK blah

  18. Drug detection and analysisinfrared spectroscopy

  19. H NMR

  20. ethanol

  21. Steroid detection • Non-polar • Steroid backbone • Anabolic steroids • Promote tissue growth • Breast growth in men • Acne • Infertility • Mood swings • Aggressiveness • High blood pressure, heart attack, stroke • Liver disease

  22. Steroids are broken down to metabolites in the body • Detected by gas chromatography and mass spectrometry from urine Separation depends on how quickly components travels (solubility in the liquid stationary phase). More soluble slower component

  23. Detection of alcohol • Breathalyzers • Redox acidified dichromate • Orange to green • (dichromate to chromium III ion) • Alcohol to aldehyde to acid

  24. Fuel cell • Two Pt electrodes • Oxidizes the alcohol • Converts energy into electrical energy • Oxygen is reduced

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