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Asked by Mirrorworld to Angela, Claire, Ian, Robert, Sarah on 17 Nov 2014. This question was also asked by lol.
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Ian Cade answered on 17 Nov 2014:
I do like a nice Wittig reaction:
Take an aryl methylbromide dissolve it, add some triphenylphosphine to make the phosphonium bromide. Then dissolve that in THF, add potassium t-butoxide (strong-ish base) to make the ylide and then add an aldehyde. The two react to make an alkene.
Why do I like it, well:
In my case the phosphonium salt intermediate was a nice pale yellow solid that crystallised well (meaning I could get it pure fairly easily).
When it reacted with t-butoxide it went from pale yellow to a deep beetroot purple.
The structure of this purple material has a C=P double bond… or C(-)-P(+)… which is a little unusual.
When the purple material reacted with my aldehyde the purple disappeared to give a yellow solution that fluoresced green. (meaning I knew the reaction was working just by looking at it).
And I like the word ‘ylide’ (a name for the purple intermediate)
The Sonogashira coupling isn’t bad either.
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Angela Stokes answered on 18 Nov 2014:
Hi Mirrorworld
Difficult to say really – chemical reactions happen all around us everyday, but one of my favourite days of the year is bonfire night and I love to see the fireworks…..so I guess the reactions that happen in fireworks are my favourite…..it is also fun to be able to explain them to people too….most are mighty impressed lol!I answered a question yesterday on how fireworks get there colours – if you want to know have a look at that answer, let me know if you can’t find it and I’ll write it again.
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Sarah Harris answered on 19 Nov 2014:
Hi Mirrorworld,
I found out about a really cool looking one the other day – burning ammonium dichromate (NH4Cr2O7) with mercury thiocyanate (HgSCN). The reaction looks a bit like a kraken crawling out of a fiery hellpit – its AMAZING. There’s a video of it here:
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