Amines (A-level only)

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Question 4

This question is about the preparation of pentan-2-ol. Pentan-2-ol does not mix with water and has a boiling point of $119∘C119^\circ\text{C}$ .

Pentan-2-ol can be prepared from pent-1-ene using this method:

a Measure out $cm312.5\text{ cm}^3$ of pent-1-ene into a boiling tube in an ice bath.
b Carefully add $cm35\text{ cm}^3$ of concentrated phosphoric acid to the pent-1-ene.
c After 5 minutes, add $cm310\text{ cm}^3$ of distilled water to the mixture and transfer the boiling tube contents to a separating funnel.
d Shake the mixture and allow it to settle.
e Discard the lower (aqueous) layer.
f Add a fresh $cm310\text{ cm}^3$ sample of distilled water and repeat steps d and e.
g Transfer the remaining organic liquid to a beaker.
h Add $g2\text{ g}$ of anhydrous sodium sulfate and allow to stand for 5 minutes.
i Filter the mixture under reduced pressure.
j Distil the filtrate and collect the distillate that boils in the range $110–130∘C110\text{--}130^\circ\text{C}$ .

It is important to wear eye protection and a lab coat when completing this experiment. Suggest, with a reason, one other appropriate safety precaution for this experiment.

[2]

Give a reason for adding the distilled water in steps c and f.

[1]

Give a reason for adding anhydrous sodium sulfate in step h.

[1]

Standard filtration under reduced pressure uses a specialized flask connected to a vacuum pump. Identify two other essential pieces of equipment/glassware needed to perform this filtration.

[2]

Identify the most likely organic impurity, other than pent-1-ene, in the distillate collected in step j. Suggest one reason why it could be difficult to remove this impurity.

[2]

Calculate the mass, in $g\text{g}$ , of pentan-2-ol formed from $cm312.5\text{ cm}^3$ of pent-1-ene if the yield is $34.0%34.0\%$ . Give your answer to 1 decimal place. (Density of pent-1-ene = $cm−30.641\text{ g cm}^{-3}$ ).

[4]

Amines (A-level only)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Question 4

This question is about the preparation of pentan-2-ol. Pentan-2-ol does not mix with water and has a boiling point of $119∘C119^\circ\text{C}$ .

Pentan-2-ol can be prepared from pent-1-ene using this method:

a Measure out $cm312.5\text{ cm}^3$ of pent-1-ene into a boiling tube in an ice bath.
b Carefully add $cm35\text{ cm}^3$ of concentrated phosphoric acid to the pent-1-ene.
c After 5 minutes, add $cm310\text{ cm}^3$ of distilled water to the mixture and transfer the boiling tube contents to a separating funnel.
d Shake the mixture and allow it to settle.
e Discard the lower (aqueous) layer.
f Add a fresh $cm310\text{ cm}^3$ sample of distilled water and repeat steps d and e.
g Transfer the remaining organic liquid to a beaker.
h Add $g2\text{ g}$ of anhydrous sodium sulfate and allow to stand for 5 minutes.
i Filter the mixture under reduced pressure.
j Distil the filtrate and collect the distillate that boils in the range $110–130∘C110\text{--}130^\circ\text{C}$ .

It is important to wear eye protection and a lab coat when completing this experiment. Suggest, with a reason, one other appropriate safety precaution for this experiment.

[2]

Give a reason for adding the distilled water in steps c and f.

[1]

Give a reason for adding anhydrous sodium sulfate in step h.

[1]

Standard filtration under reduced pressure uses a specialized flask connected to a vacuum pump. Identify two other essential pieces of equipment/glassware needed to perform this filtration.

[2]

Identify the most likely organic impurity, other than pent-1-ene, in the distillate collected in step j. Suggest one reason why it could be difficult to remove this impurity.

[2]

[4]

Amines (A-level only)

Question 4

Amines (A-level only) Questions

Amines (A-level only)

Question 4

Amines (A-level only) Questions