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What's in a Medicine?

Functional Groups
1. Carboxylic acid
  1. Acid anhydride
  2. Can be attached to a benzene ring
  3. Has a high enough H+ conc to react with carbonates to produce CO2
2. Ester
  1. Alcohol + Carboxylic acid
    1. Ethanol + ethanoic acid = ethyl ethanoate + wayer
    2. Catalyst: conc sulfuric or conc hydrochloric
    3. Heated under reflux
    4. Reversible - forms equilibrium
    5. Alcohol - yl
    6. Carboxylic acid - oate
  2. Alcohol +Acid anhydride
    1. More reactive than carboxylic acids
    2. React completely - higher yield of ester
    3. Produce carboxylic acid + ester
    4. Ethanoic anhydride
3. Ether
  1. Same molecular formular as alcohols (structural isomer)
  2. General formula: R-O-R
  3. Longer chain is chosen as parent alkane (second name)
  4. e.g. methoxyethane
4. Carbonyl group C=O
  1. Aldehyde
    1. Carbonyl group on the end of the chain
    2. Suffix -al
  2. Ketone
    1. Carbonyl group within an alkane chain
    2. Suffix -one
Alcohol
1. Primary
  1. -OH bonded to a carbon bonded to ONE other carbon atom
  2. Butan-1-ol
  3. RCH2OH
2. Secondary
  1. -OH bonded to a carbon bonded to TWO other carbon atoms
  2. Butan-2-ol
  3. RCH(OH)R
3. Tertiary
  1. -OH bonded to a carbon bonded to THREE other carbon atoms
  2. 2-methylpropan-2-ol
  3. R2C(OH)R
4. Formation of esters
5. Oxidation
  1. Conditions
    1. Heating under reflux
    2. Under the presence of an oxidising agent
    3. Acidified potassium dichromate (VI) solution
  2. Products
    1. Primary alcohol
      1. Alcohol in excess - distilation
        Aldehyde
      2. Oxidising agent in excess - reflux
        Carboxylic acid
    2. Secondary alcohol
      1. Ketones
  3. Final colour
    1. Primary
    2. Secondary
    3. Tertirary
6. Dehydration
  1. Forms alkenes
  2. Heated Al2O3 at 300ºC or refluxing with conc H2SO4
  3. Elimination reaction
    1. Molecule of water is removed
7. Substitution
  1. Nucleophilic substitution with halide ions
  2. Presence of a strong acid
  3. Produces haloalkanes
8. Hydrogen bonds raise the boiling point and make them soluble, but solubility decreases as chain length increases
9. Don't react with strong bases or carbonates
Phenol
1. Reactivity
  1. Ethanol < water < phenol < carboxylic acids
  2. Ethanol and water are only slightly acidic
  3. Phenols and carboxylic acids can react with strong bases to form salts
    1. e.g. NaOH
    2. Remain in solution after the reaction
  4. Phenols won't make carbonates fizz
2. Test with neutral iron (III) chloride to give a purple colour
  1. -C=C--OH group forms a complex with Fe3+
3. Reacts with acid anhydride
  1. Alkaline conditions
  2. Phenol + ethanoic anhydride -> phenyl ethanoate + ethanoic acid
4. DOES NOT react with carboxylic acids to produce an ester
Making a solid organic product
1. Purification
  1. Reduced pressure filtration
    1. 1. Connect a conical flask to a vacuum pump via the side arm
    2. 2. Dampen a piece of filter paper and place it flat in the Buchner funnel
    3. 3. Switch the vacuum pump on and then carefully pour in the mixture to be filtered
    4. 4. Disconnect the flask from the vacuum pump before turning the pump off to avoid 'suck back'
    5. Used to separate a solid from a filtrate rapidly
  2. Recrystalisation
    1. Used to purify solid crude organic productss with small amounts of impurities
    2. 1. Chose the correct solvent
      1. Desired product must be very soluble in solvent when it is hot, but be insoluble when solvent in cold
    3. 2. Dissolve the mixture in the minimum quantity of hot solvent
      1. The smaller the amount of solvent used, the better the yeild of purified product
    4. 3. Filter to remove any insoluble impurities and retain the filtrate
      1. It is best to preheat the filter funnel and conical flask to prevent any solid crystallising out
    5. 4. Leave the filtrate to cool until crystals form
    6. 5. Collect the crystals by vaccum filtration
      1. Remove soluble impurities
    7. 6. Dry the crystals in an oven or in the open, covered by an inverted filter funnel
2. Melting point determination
  1. Used as evidence of a solid products purity and identity
  2. 1. Seal the end of a glass melting point (capillary) tube by heating it to melting in a bunsen flame
  3. 2. Put a small amount of the solid into the open end of the tube, and tap the tube so that the solid falls to the bottom of the sealed end
  4. 3. Fix the tube in the melting point apparatus and heat the surrounding liquid gently, stirring to ensure even heating throughout. The temperature should rise very slowly
  5. 4. Note the temperature that the solid starts and finishes melting. The difference between the highest and lowest temperatures recorded is known as the melting range
  6. 5. Compare experimental value to published value. The wider the range, the more impure the substance
    1. A pure compound should melt within 0.5ºC of its true published melting point
3. Thin layer chromatography
  1. Used to separate small quantities of organic products
    1. To check purity or to purify
    2. To follow the progress of a reaction over time
  2. Requires a suitable solvent as different organic compounds have a different affinity with each solvent
  3. Chromatography paper is paper chromatography
  4. Using a silica plate is thin layer chromatography
  5. 1. Spot test mixture and reference samples on a pencil line 1cm from the base of the plate or paper
  6. 2. Suspend the plate in a beaker containing the solvent, ensuring the solvent does not touch the samples. Cover beaker with a watch glass to prevent evaporation
  7. 3. Remove plate when the solvent front is near the top. Mark how far the solvent has reached and allow to dry
  8. 4. Locate the spots of samples using iodine, ninhydrin, or under an ultraviolet lamp
  9. 5. Match heights reached (Rf values) of sample with those of known compounds
    1. Rf = distance travelled by spot divided by distance moved by solvent
Making a liquid organic product
1. Heating under reflux
  1. Used for volatile and flammable liquids
  2. 1. Put reactants into a pear-shaped flask and add anti-bumping granules
    1. These burst the bubbles in the boiling mixture and reduce the chance of boiling over
  3. 2. Do not stopper the flask
    1. This would cause the pressure to build up and glassware could crack
  4. 3. Atttach a condenser vertically to the flask so that water flows into the condenser at the bottom and out the condenser at the top
    1. This ensures the condenser is always full of cold water
  5. 4. Heat so that the reaction mixture boils gently, using a Bunsen flame or heating mantle. The liquid should drip back into the reaction flask steadily
    1. Vapours should reach no more than half way up the condenser before being condensed back into liquid
2. Purifying
  1. When the organic produce is mixed with another immiscible liquid, the layers can be separated using a separating funnel.
    1. 1. Allow the layers to settle, leaving the denser layer on the bottom
    2. 2. Run off and dispose of the aqueous layer
    3. 3. Run the organic layer into a clean conical flask
  2. If acidic purities are present, add soduim hydrogen carbonate solution and shake well to remove them.
  3. If the crude product is alkaline and needs neutralising, add dilute acid until the mixture is neutral
  4. Dry the crude product by adding anhydrous sodium sulfate and swirling the mixture
    1. Other anhydrous salts, such as calcium chloride, can also be used
  5. The pure product can then be separated by distilation
3. Preparing liquid product
Green chemistry
1. Developing chemical products and processes that are as sustainable and as environmentally friendly as possible
2. Better atom economy
  1. More of the feedstock is incorporated into the product and fewer waste products are produced
3. Prevention of waste products
  1. This is better than treating and disposing waste
4. Less hazardous chemical synthesis
  1. Using less hazardous chemicals in the reaction
5. Safer chemical products
6. Use safer solvents
  1. Minimise the use of organic solvents
7. Lower energy usage
  1. Lower temperature and pressure processes mean it is more sustainable
8. Use renewable feedstocks instead of depleting natural resources
9. Reduce reagents used and the number of steps, as these can generate watse
10. Use catalysts and more selective catalysts
  1. These reduce energy usage and waste products
11. Design chemical products for degredation
  1. When released into the environment, they should break down into harmless substances instead of degrading the environment
12. Use real time process monitoring to reduce waste products
13. Use safer chemical processes
  1. Reduce the potential of gas release, fires, and explosions
Analytical techniques
1. Mass spectrometry
  1. M+ Peak is the mass of the heaviest element.
    1. This is the molecular ion and helps to determine the molecular mass of the compound being analysed
  2. Used to find atomic mass and relative abundances of isotopes in an element.
  3. Other peaks are due to positive ions from fragments
    1. The fragmentation pattern
  4. M+1 peak caused by 13C isotope
2. Infrared
  1. Specific frequencies make specific bonds in organic molecules vibrate more
    1. Energy of molecules is quantised - they must take a small number of definite energy values
  2. Determines functional groups but not the number of them or where they are in a molecule
  3. Exposes substances to 10[14]-10[13] Hz frequency, which makes vibrational energy changes occur in the molecules
  4. Frequency and wavelength are related
    1. Speed of light c = wavelength λ x frequency v
    2. Speed of light is constant
    3. frequency = 1/ λ
      1. Wavenumber of radiation measured in cm
  5. SImple molecules have less complex spectra
  6. Weaker bonds require less energy to vibrate
  7. Below 1500 is the fingerprint region, which is not used to determine functional groups

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What's in a Medicine?

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	Created by Tamsyn Dawson over 7 years ago