Download - How can we change ethanol
![Page 1: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/1.jpg)
![Page 2: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/2.jpg)
How can we change ethanol...
![Page 3: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/3.jpg)
...to ethene...
![Page 4: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/4.jpg)
...and water?
![Page 5: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/5.jpg)
We need an elimination reaction.
![Page 6: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/6.jpg)
The reaction is also called dehydration because water is eliminated from the ethanol.
![Page 7: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/7.jpg)
The ethanol must be heated to about 180 °C with concentrated sulphuric acid or phosphoric acid.
![Page 8: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/8.jpg)
Alternatively, ethanol vapour can be passed over alumina, Al2O3, at 350 °C.
![Page 9: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/9.jpg)
Although the reaction looks simple, it happens in more than one step.
![Page 10: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/10.jpg)
This is the start of the mechanism for the elimination of water from ethanol using concentrated sulphuric acid.
![Page 11: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/11.jpg)
A covalent bond begins to form between the oxygen atom in the hydroxyl group and ahydrogen atom in a sulphuric acid.
![Page 12: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/12.jpg)
The bond between the hydrogen atom and the rest of the sulphuric acid molecule begins to break.
![Page 13: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/13.jpg)
A protonated alcohol is formed.
![Page 14: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/14.jpg)
The pair of electrons in the C-O bond is attracted to the positive charge and the bond begins to break.
![Page 15: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/15.jpg)
When the C-O bond breaks a molecule of water is eliminated.
![Page 16: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/16.jpg)
The remainder of the ethanol molecule is now a positively charged ion, called a carbocation.
![Page 17: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/17.jpg)
A new bond begins to form between the two carbon atoms.
![Page 18: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/18.jpg)
A bond begins to form between the hydrogensulphate ion and one of the hydrogen atoms.
![Page 19: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/19.jpg)
The products of the reaction are ethene...
![Page 20: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/20.jpg)
... and water.
![Page 21: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/21.jpg)
Notice that, overall, sulphuric acid has not been used up in the reaction so it behaves as a catalyst.
![Page 22: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/22.jpg)
This is the start of the simplified mechanism for the elimination of water from ethanol.
![Page 23: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/23.jpg)
A covalent bond begins to form between the oxygen atom in the hydroxyl group and a hydrogen ion.
![Page 24: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/24.jpg)
A protonated alcohol is formed.
![Page 25: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/25.jpg)
The pair of electrons in the C-O bond is attracted to the positive charge and the bond begins to break.
![Page 26: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/26.jpg)
When the C-O bond breaks a molecule of water is eliminated.
![Page 27: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/27.jpg)
The remainder of the ethanol molecule is now a positively charged ion, called a carbocation.
![Page 28: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/28.jpg)
A new bond begins to form between the two carbon atoms.
![Page 29: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/29.jpg)
The product of the reaction are ethene…
![Page 30: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/30.jpg)
…and water.
![Page 31: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/31.jpg)
Notice that, overall, the hydrogen ion has not been used up in the reaction so it behaves as a catalyst.
![Page 32: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/32.jpg)
This is butan-2-ol, a secondary alcohol.
![Page 33: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/33.jpg)
If it is heated to 180 °C with concentrated sulphuric acid, two alkenes form.
![Page 34: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/34.jpg)
In the first stage of the reaction mechanism a protonated alcohol forms.
![Page 35: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/35.jpg)
The C-O bond breaks.
![Page 36: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/36.jpg)
A secondary carbocation is formed and water is eliminated.
![Page 37: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/37.jpg)
There are two hydrogen atoms next to the positively charged carbon atom in the carbocation.
![Page 38: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/38.jpg)
This hydrogen atom can be removed.
![Page 39: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/39.jpg)
And so can this hydrogen atom.
![Page 40: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/40.jpg)
Two different alkenes can be produced.
![Page 41: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/41.jpg)
But-2-ene…
![Page 42: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/42.jpg)
...and…
![Page 43: How can we change ethanol](https://reader036.vdocuments.pub/reader036/viewer/2022081422/568164aa550346895dd6ab6e/html5/thumbnails/43.jpg)
...But-1-ene.