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Separating stereoisomers

Learn about the process of separating stereoisomers, extracting drugs, and using radioisotopes for cancer treatment. Explore key techniques such as chiral chromatography, extraction methods, and targeted alpha therapy. Discover the science behind nuclear medicine, radiotherapy, and advanced imaging technologies.

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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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