How do you convert ethanol into propene???

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Mollypop1996
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How do you convert ethanol into propene???
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charco
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(Original post by Mollypop1996)
How do you convert ethanol into propene???
That there are several ways to do it. The method chosen probably depends on your course's requirements.

Maybe oxidise the ethanol to ethanal (distil with acidic potassium dichromate)
React with methyl magnesium bromide (Grignard), acidic workup.
Dehydrate with conc. phosphoric acid at 350ºC
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Pigster
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It depends on how much you need.

I have some propene and am willing to swap it for ethanol.

Mmmm, lovely yummy ethanol.

Failing that, and assuming it was an AQA student asking I'd HBr it, then H+/CN-, then acid hydrolysis of the nitrile, then LiAlH4, followed by dehydration.
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Mollypop1996
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What does each stage produce? I need to do it via an alkene
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Adam_1999
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(Original post by Mollypop1996)
What does each stage produce? I need to do it via an alkene
Add KCN, nucleophillic substitution to get propanenitrile, then acid hydrolysis to get propanoic acid. Add ANHYDROUS LiAlH4 to reduce it to propan-1-ol, then dehydrate to make propene.
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Adam_1999
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Another way is dehydrate ethanol to make ethene, add HBr (electrophillic addition) to make bromoethane, add KCN to make propanenitrile via nucleophillic substitution, acid hydrolysis to make propanoic acid. Reduce this using LiAlH4 dissolved in dry ether to propan-1-ol, then dehydrate again to make propene.

https://youtu.be/U9t-slLl30E
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alow
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(Original post by Adam_1999)
Another way is dehydrate ethanol to make ethene, add HBr (electrophillic addition) to make bromoethane, add KCN to make propanenitrile via nucleophillic substitution, acid hydrolysis to make propanoic acid. Reduce this using LiAlH4 dissolved in dry ether to propan-1-ol, then dehydrate again to make propene.

https://youtu.be/U9t-slLl30E
That's a lot of steps.

(Original post by Mollypop1996)
What does each stage produce? I need to do it via an alkene
The product is an alkene.

You already have the standard A Level answer from Pigster.

A different option would be a Wittig reaction, where MePPh3+Br- is deprotonated by a strong base (say BuLi), forming an ylid, to which ethanal is added which you make by oxidising ethanol. This is arguably a better (and practically much quicker) method, but involves reactions you don't learn about at A Level.
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