Organic Chemistry

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Organic Chemistry
2010-05-31 14:56:55

Organic Chemistry
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  1. Alcohols can be _____, _____ or _____.
    • Primary
    • Secondary
    • Tertiary
  2. The alcohol series has the general formula:
  3. An alcohol is primary, secondary or tertiary depending on...
    Which carbon atom on the hydroxyl group -OH is bonded to.
  4. -OH can be swapped for halogen to make a ______.
  5. Tertiary alcohols are more _____ than either primary or secondary alcohols.
  6. To make a chloroalkane you can just...
    (With a tertiary alcohol)
    Shake a tertiary alcohol with HCl. This gives you an impure chloroalkane.
  7. Primary and secondary alcohols react ___ ____ to be made this way. You need to use the phosphorus (III) halide method. Which is....
    Too slowly.

    To make a chloroalkane by reacting an alcohol with PCl3. But, PBr3 and PI3 are usually made in situ by refluxing the alcohol with 'red phosphorus' and either bromine or iodine.

    The general equation is :

    3ROH + PX3 → 3RX + H3PO3
  8. Chloroalkanes can also be made using Phosphorus (V) Chloride. What is the general equation of this:
    ROH (l) + PCl5 (l) → RCl (l) + HCl (g) + POCl3 (l)
  9. What reaction involving phosphorus (V) chloride to test for the -OH group?
    Add the phosphorus (V) chloride to the unknown liquid.

    If -OH is present, you would get steamy fumes of HCl has, which dissolve in water to form chloride ions. You can then test for chloride ions using silver nitrate. The steamy fumes of HCl gas also turn moist blue litmus paper red (Because HCl dissolves to form a strong acid)
  10. Alcohols react with sodium to produce what?
  11. Sodium metal reacts gently with ethanol. Give the equation for this reaction:
    2CH4CH2OH + 2Na → 2CH3CH2O-Na+ + H2

    The longer the hydrocarbon chain of the alcohol gets, the less reactive it is with sodium.
  12. The hydroxyl group -OH can form _____ bonds.
  13. Hydrogen bonding is the ______ kind of intermolecular force, so it gives alcohols ____ boiling points compared to non-polar compounds.
    • Strongest
    • High
  14. When you mix an alcohol with water, hydrogen bonds can also form between the...
    -OH and the H20
  15. If it's a ____ alcohol such as methanol, hydrogen bonding lets it mix freely with water - its ____ in water.
    • Small
    • Miscible
  16. In larger alcohols, most of the molecule is a non-polar carbon chain, so there's ___ attraction for the polar H20 molecules. This means that as alcohols increase in size, their miscibility in water ____.
    • Less
    • Decreases
  17. Small alcohols are also miscible in ________ solvents such as cyclohexane.
  18. Alcohols burn to produce...
    CO2 and H20
  19. It doesn't take much to set ethanol alight and it burns with a ____ ____ flame.

    The C-C and C-H bonds are broken as the ethanol is ______ _____ to make carbon dioxide and water. This is a _____ reaction
    Pale blue

    • Completely oxidised
    • Combustion
  20. How much an alcohol can be oxidised depends on its ...
  21. You can use the oxidising agent _____ ____ _____ to mildly oxidise alcohols.
    Acidified potassium dichromate
  22. Primary alcohols are oxidised to...

    Secondary alcohols are oxidised to...

    Tertiary alcohols...
    Aldehydes and then to Carboxylic acids

    Ketones only

    Won't be oxidised
  23. Aldehydes and ketones are _____ compounds - they have the functional ____. THeir general formula is:
    • Carbonyl
    • C=O

  24. Aldehydes have a _____ and ___ alkyl group attached to the carbonyl carbon atom such as propanal.
    • Hydrogen
    • One
  25. Ketones have ___ alkyl groups attached to the carbonyl carbon atom such as propanone.
  26. How do you oxidise a primary alcohol - Making a aldehyde.

    Using ethanol.
    1) Gently heading ethanol with ethanol with potassium dichromate (VI) solution and sulfuric acid in a test tube should produce a "apple" smelling ethanal (an aldehyde). However, it's really tricky to control the amount of heat and the aldehyde is usually oxidised to form a "vinegar" smelling ethanoic acid.

    2) To get just the aldehyde, you need to get it out of the oxidising solution as soon as it's formed.

    You can do this by gently heating excess alcohol with a controlled amount of oxidising agent in distillation apparatus, so the aldehyde (which boils at a lower temperature than the alcohol) is distilled off immediately.

    3) Distillation is use in many other processes to purify a product - you just collect the fraction that vaporises around the boiling point of the compound your after.
  27. Volatile liquids can be tricky to work with. If you need to heat a volatile liquid for a reaction, you can end up with most of the liquid _____ before it has a chance to react.

    You can get around this by fitting a _____ _____. Which is...

    Reflux condenser

    A condenser that is fitted vertically to the reaction flask. It's a very common technique in preparing organic liquids.
  28. Oxidising a Primary Alcohol - Making a carboxylic acid
    1) To produce the carboxylic acid, the alcohol has to be vigorously oxidised. The alcohol is mixed with excess oxidising agent and heating under reflux

    2) Heating under reflux means you can increase the temperature of an organic reaction to boiling without losing volatile solvents, reactants or products. Any vaporised compounds are cooled, condense and drip back into the reaction mixture.
  29. Secondary alcohols will oxidise to _____
  30. Refluxing a secondary alcohol such as propan-2-ol with _____ __________ will produce a _____.

    They can't be oxidised easily, so even prolonged refluxing won't produce anything more.
    Acidified dichromate (VI)

  31. Tertiary alcohols don't react with potassium dichromate (VI) at all - the solution stays ____. The only way to oxidise tertiary alcohols is by _____ them.
    • Orange
    • Burning
  32. Aldehydes and ketones can be distinguished using _____ _____

    Aldehydes are easily ____ but ketones aren't.
    Oxidising agents

  33. What are the three oxidising agents you could use to distinguish between aldehydes and ketones and how they show which each one is?
    • Fehling's solution
    • Benedict's solution

    They are both deep blue Cu2+ complexes, which reduce to brick-red Cu2O when warmed with an aldehyde but stay blue with a ketone.

    Tollen's reagent.

    Is [Ag(NH3)2]+ - its reduced to silver when warmed with an aldehyde, but not with a ketone. The silver will coat the inside of the apparatus to form a silver mirror.
  34. Halogenalkanes are alkanes with ____ atoms.
  35. Primary, secondary and tertiary halogenalkanes have different ______.
  36. What is the experiment to compare the reactivity of the three types of halogenalkanes?
    1) When you mix a halogenalkane with water, it reacts to form a alcohol

    R-X + H20 → R-OH + H+ + X-

    2) If you put silver nitrate solution in the mixture too, the silver ions react with the halide ions as soon as they form, giving a silver halide precipitation.

    • Ag+ (aq) + X- (aq) → AgX (s)
    • 3) To compare the reactivities, set up three test tubes each containing a different halogenalkane (They should all be isomers to make it a fair test), ethanol (as a solvent) and silver nitrate solution (this contains water)

    • 4) In the tube with the tertiary halogenalkane, a precipitate of silver bromide forms immediately.
    • With the secondary halogenalkane it takes several seconds.
    • With the primary halogenalkane, it takes several minutes.
  37. Halogenalkanes have many uses. What are 3 of these uses?
    1) Halogenalkanes can be used to produce some useful polymers. For example, PVC

    2) Some are used as refrigerants. For example, to cool the air in the fridge. They're suitable for this because they're easily compressed and they don't corrode pipework.

    3) Some non-flamable halogenalkanes are used as fire retardants or flame retardants. For example, in the plastic parts of computers.
  38. Halogenalkanes may react by _______ _______.
    Nucleophilic Substitution
  39. Halogens are much more ______ than carbon. So the _____ bond is _____.
    • Electronegative
    • C-X (Carbon Halogen)
    • Polar
  40. The δ+ carbon doesn't have enough _____. THis means it can be attacked by a _______.
    • Electrons
    • Nucleophile
  41. A nucleophile's an....
    Electron pair donor. It donates an electron pair to somewhere without enough electrons.
  42. What are two examples of nucleophiles that react readily with halogenalkanes?
    • NH3
    • OH-
  43. What is the mechanism for nucleophilic substitution?

    1) X is the halogen. Nuc is the nucleophile, which provides a pair of electrons for the Cδ+

    2) The C-X bond breaks heterolytically - both electrons from the bond are taken by the halogen

    3) The halogen falls off as the nucleophile bonds to the carbon.