Alkyl Halide Synthesis

1
Alkyl Halide Synthesis

• Our Goals Today
• Learn how to set-up a reflux apparatus.
• Learn how to perform an organic extraction /
  washing using a seperatory funnel.
• Synthesize n-butyl bromide.
• Synthesize t-pentyl chloride.

2
The SN2 Reaction
SN2 - Substituion Nucleophilic Bimolecular
3
Synthesis of n-Butyl Bromide
Possible Detour
Carbocation
4
Carbocation Stability
gt
gt
2
1
3
5
Side Products of n-Butyl Bromide Synthesis
6
Refluxing a Reaction

• A reflux apparatus is used when a
• reaction is heated about the boiling of
• one of the components in the flask.
• Volitile chemicals are condensed back
• into the reaction flask via cooling
• action from the water-jacketed
• condenser.

Water Out
Water In
Variac Settings for n-Butyl Bromide Synthesis 0
10 min (stirring at room temperature) 60 45
min 70 10 min
To Variac
7
Organic Extraction / Washing
Mixture
n-BuBr H2O
Top
Bottom
n-BuBr
H2O
cold 1M HCl
Top
Bottom
Density n-BuOH
0.81 n-BuBr 1.28 H2O
1 HCl 1.16 t-pentyl OH
0.805 t-pentyl Cl 0.866 H2SO4
1.86
n-BuBr
HCl BuOH alkenes
H2O
Top
Bottom
n-BuBr
H2O HCl
Na2CO3 (dissolved in H2O)
Top
Bottom
Na2CO3
n-BuBr
8
Synthesis of t-Pentyl Chloride

• You will need to determine the extraction /
  washing flow chart for this reaction
• in order to determine which layer is your
  t-pentyl chloride.
• You will also need to determine all the side
  products for this reaction (with
• their reaction pathway!) for your report.
• HINT Follow the precedence set by the
  n-butyl bromide synthesis.

9
Your Task

• Synthesize n-butyl bromide.
• Correctly set-up the reflux apparatus for the
  n-butyl bromide synthesis.
• Synthesize t-pentyl chloride.
• Construct correct organic extraction / washing
  flow chart.

10
Advisory

• Make sure the reflux apparatus is set up
  correctly.
• Make sure the distillation apparatus is set up
  correctly.
• Use extreme caution when working with
  concentrated acids (gloves!).
• Each synthesis has its own hood for dispensing
  chemicals.
• There is 1M HCl and Conc. HCl, make sure you use
  the correct one.
• Make sure you are working with the correct layer
  that has your product when performing the organic
  extraction.
• Save all your layers until you are completely
  done.
• Turn in your n-butyl bromide and t-pentyl
  chloride in vials before you leave today.
• Clean up after yourselves!