Talk:Ninhydrin

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The writer(s) forgot to add whether it was a solid, liquid or gas in its pure state.

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 23 August 2021 and 10 December 2021. Further details are available on the course page. Student editor(s): Meganmwolf.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 05:18, 17 January 2022 (UTC)[reply]

Wrong structure?

Yes, 5 bonds do not fit here.

One of the carbon atoms on the right side of the bottom-right structure diagram has 5 bonds. Does anyone know what the correct structure is, and if so, could you please change it? ~GMH 05:02, 22 July 2005 (UTC)[reply]

I agree. Carbon can't have 5 bonds... at least I didn't think it could.

Yes, there is a mistake. There is a part of the molecule which can't have a mesomeric effect. I uploaded a modified image. --Totophe64 19:02, 27 December 2005 (UTC)

Woops, there was no copyright on the picture, so it got deleted ! I didn't know that it was possible to copyright the description of chemical reactions, as this is not the creation of somebody, but something which is "natural" ... Ow I love copyrights ! --Totophe64 15:35, 10 March 2006 (UTC)

I thought also that the ejected part of the amino acid was an aldehyde.

"Triketohydrindane hydrate", i can only see two "ketos". What's wrong, the image or the name?

That is "Triketohydrindane hydrate", a H2O molecule is added to the third ketone, which becomes diol on the same Carbon atom. Ray Leung 10:29, 10 March 2006 (UTC)[reply]

I'm currently doing research using ninhydrin that proves/shows that the two hydroxide groups are actually one double bonded oxygen. Actually it's an equilibrium reaction between the two when in water.

--Nbx909 (talk) 00:10, 18 April 2008 (UTC)[reply]

Hey... I'm not very smart and scientific, but i was wondering, Could one make something like ninhydrin at home? —Preceding unsigned comment added by 68.38.217.227 (talk) 13:14, 10 April 2010 (UTC)[reply]

Reaction right?

Hey, which reaction is right? The one depiced in the french wiki or the one depicted here? they do differ! Or do both reactions exist? --92.194.175.11 (talk) 10:57, 16 July 2010 (UTC)[reply]

fr:Fichier:Nihydrine réaction2.png? Definitely wrong. Looks similar to the same mistake discussed years ago on this talk-page, with carbon having 5 bonds. DMacks (talk) 16:24, 16 July 2010 (UTC)[reply]

Okay, I actually looked at French article, and the chemistry described also contradicts the English (even if the structures were corrected). I think .fr proposing degradation of the amino acid into RCHO + NH3 + CO2 as a redox process with a reduced-form of ninhydrin as product, and then Schiff base formation starting with the free ammonia. That's quite different than the .en condensation of ninhydrin with the amine-terminus, then decarboxylation, followed by the second ninhydrin bonding. Contradictions: order of reaction, and if there is free NH3 as an intermediate! The following article says it has a followup article that sounds like it would be good actual study of this issue:

"ON THE MECHANISM OF THE REACTION OF NINHYDRIN WITH a-AMINO ACIDS. II. A SPECTROPHOTOMETRIC STUDY OF HYDRINDANTIN REACTIONS". J. Biol. Chem. 186: 13–22. 1950. {{cite journal}}: Unknown parameter |authors= ignored (help)

but I can't find it at the moment. The reaction is in the scope of many undergrad-orgo courses if someone has a textbook handy. DMacks (talk) 16:58, 16 July 2010 (UTC)[reply]

Proline

This help request has been answered. If you need more help, please place a new {{help me}} request on this page followed by your questions, or contact the responding user(s) directly on their user talk page.

I just had a doubt. Why does proline reacts differently with ninhydrin, is it because of a tertiary carbon atom in proline? If so, can some one tell me which carbon atom it is? Sharoncv (talk) 22:20, 12 September 2011 (UTC)sharoncv[reply]

Hey Sharon, you'll probably get a quicker and more accurate response to your question if you contact the editors of this specific article, or a member of the Wikiproject, linked at the top of the page. The help request process template is ideally for more general assistance. Cind.amuse (Cindy) 22:59, 12 September 2011 (UTC)[reply]

Except for glycine, the other standard amino acids all also have the same numbers and types of bonds on the carbons. Here are some thought questions to help figure out what is different though. What other atom involved in the reaction is noticeably different for proline vs other amino acids? Does ninhydrin react with any amino acid in a protein chain, or only one at a certain position? DMacks (talk) 23:09, 12 September 2011 (UTC)[reply]