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Topic: Why does pure HCN not react with aldehydes and ketones?  (Read 4951 times)

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Offline Steenrod

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Why does pure HCN not react with aldehydes and ketones?
« on: November 13, 2012, 01:36:07 PM »
Why does pure HCN not react with aldehydes and ketones?


Thanks.
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Offline discodermolide

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #1 on: November 13, 2012, 01:40:52 PM »
Have you any ideas as to this reaction?
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Offline Steenrod

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #2 on: November 13, 2012, 01:46:17 PM »
I regret to say "None";my knowledge is superficial. :(

All I know is that this the cyanoydrin reaction.
I am horrible at chemistry.I am always liable to fail my chemistry exams.So, sorry for stupid questions.

Offline discodermolide

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #3 on: November 13, 2012, 01:52:38 PM »
Well what do you know about cyanohydrin formation?
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Offline orgopete

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #4 on: November 13, 2012, 06:10:33 PM »
I thought they would react. Do I not understand the question, as in literally true? In the formation of a cyanohydrin, one adds HCN.
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Offline Steenrod

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #5 on: November 14, 2012, 12:27:42 AM »
I just realized that most questions I have posted are actually standard stuff.I have not really read this systematically.

I consulted a few books(not my text!) and here is what I got:

The carbon in HCN is nucleophilic and it bonds with the carbonyl carbon.But HCN is a weak acid and so KCN or NaCN is used in order that free cyanide ion is always present in amounts sufficient to increse the rate of reaction.

So, am I right? And books seem to suggest that the reaction does occur but very slowly.So, the question is not totally correct?(LOL,I picked up a warning because of this)
I am horrible at chemistry.I am always liable to fail my chemistry exams.So, sorry for stupid questions.

Offline discodermolide

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Re: Why does pure HCN not react with aldehydes and ketones?
« Reply #6 on: November 14, 2012, 12:37:25 AM »
It seems that your books would have a reasonable answer. So they are correct and by default so are you.
http://www.chemguide.co.uk/mechanisms/nucadd/hcntt.html
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