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The best method of converting ethanol, C2 H5 OH, into iodoethane, C2 H5I, is to A he

The best method of converting ethanol, C2
H5
OH, into iodoethane, C2
H5I, is to
A heat iodine and ethanol under reflux.
B react ethanol and potassium iodide in the presence of dilute acid.
C heat potassium iodide and ethanol with concentrated sulfuric acid.
D heat red phosphorus, ethanol and iodine under reflux.

The answer is D, but can anyone please explain to me why it is this and not the others.

Thank You.
Reply 1
Original post by Linked
The best method of converting ethanol, C2
H5
OH, into iodoethane, C2
H5I, is to
A heat iodine and ethanol under reflux.
B react ethanol and potassium iodide in the presence of dilute acid.
C heat potassium iodide and ethanol with concentrated sulfuric acid.
D heat red phosphorus, ethanol and iodine under reflux.

The answer is D, but can anyone please explain to me why it is this and not the others.

Thank You.


A: The absence of the red phosporous inhibits the reaction as (I'm guessing here) it acts as a catalyst of some sort.
B: Any acid may cause the oxidation of iodine, rather than it reacting with the ethanol.
C: Using sulfuric acid encourages the dehydration of the ethanol to ethene. It will also oxidise the iodine.
Reply 2
Original post by joostan
A: The absence of the red phosporous inhibits the reaction as (I'm guessing here) it acts as a catalyst of some sort.
B: Any acid may cause the oxidation of iodine, rather than it reacting with the ethanol.
C: Using sulfuric acid encourages the dehydration of the ethanol to ethene. It will also oxidise the iodine.


thank you very much for all your help!
Original post by Linked
The best method of converting ethanol, C2
H5
OH, into iodoethane, C2
H5I, is to
A heat iodine and ethanol under reflux.
B react ethanol and potassium iodide in the presence of dilute acid.
C heat potassium iodide and ethanol with concentrated sulfuric acid.
D heat red phosphorus, ethanol and iodine under reflux.

The answer is D, but can anyone please explain to me why it is this and not the others.

Thank You.


This is my take on the answers.... Not saying above in incorrect if I answer differently.

A. Heating promotes elimination to produce ethene
B. Dilute acid could work if you removed water with a dean-stark method
C. Heating again..... Elimination (Note- you will not oxidise I2!, that is an error in the above)
D. I imagine this produces PI3 in-situ. This will act as a lewis acid to activate the alcohol group to nucleophillic substitution by the non-basic, but nucleophillic iodide ion.
Reply 4
Original post by JMaydom
This is my take on the answers.... Not saying above in incorrect if I answer differently.

A. Heating promotes elimination to produce ethene
B. Dilute acid could work if you removed water with a dean-stark method
C. Heating again..... Elimination (Note- you will not oxidise I2!, that is an error in the above)
D. I imagine this produces PI3 in-situ. This will act as a lewis acid to activate the alcohol group to nucleophillic substitution by the non-basic, but nucleophillic iodide ion.


Thank you for your help too!:smile:

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