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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: tega on May 02, 2006, 10:56:24 AM

Title: Help with homework question
Post by: tega on May 02, 2006, 10:56:24 AM
Hi,  I dunno if this is in the right place..   but my teacher asked me to:

"Out line how you would prepare and purify a solid derivative of the compound, include the name of any apparatus used and of any laboratory techniques used."

The compound being either an aldehyde or a ketone..

Any help would be great!   Thanks :D
Title: Re: Help with homework question
Post by: Morphic flip on May 08, 2006, 04:16:46 AM
Entering "prepare and purify a solid derivative" into google (change the two ** for tt) gave:

h**p://www.google.co.uk/search?hl=en&ie=ISO-8859-1&q=prepare+and+purify+a+solid+derivative&meta=

The third link down might help, I can`t view it though.

Title: Re: Help with homework question
Post by: Yggdrasil on May 08, 2006, 02:53:14 PM
If you want to make a solid derivative of an aldehyde or ketone, reacting with hydroxylamine to form an oxime is a good choice.
Title: Re: Help with homework question
Post by: Alberto_Kravina on May 08, 2006, 02:55:27 PM
Quote from: Yggdrasil on May 08, 2006, 02:53:14 PM
If you want to make a solid derivative of an aldehyde or ketone, reacting with hydroxylamine to form an oxime is a good choice.
I think that reacting with sodium bisulfite is also a method to make a solid derivate of an Aldehyde/Ketone.
Title: Re: Help with homework question
Post by: swati on May 10, 2006, 04:53:10 PM
 :)  Hello everyone
Some of the solid derivatives of an aldehyde or ketone are
1.)  oxime
      ->  prepared by reaction of  -CHO  or  >C=O  with  hydroxylamine hydrocloride
      ->  pH required  3.5  approximately
2.)  semicarbazone
      ->  prepared by reaction of  -CHO  or  >C=O  with  semicarbazide hydrochloride
      -> for its preparation, first a solution of semicarbazide hydrochloride & CH3COONa is
           prepared in order to liberate free base (semicarbazone) from its salt
      ->  recrystallize  from  alcohol
3.)  2,4-DNP hydrazone
      ->  prepared by reaction of  -CHO  or  >C=O  with  2,4-DNP hydrazine hydrochloride
      ->  recrystallize  from  alcohol