Talk:Ascorbic acid

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Vitamin C?[edit]

Exactly how is vitamin C different from ascorbic acid? Even if strictly true in a chemical sense, a good encyclopadia will take the average reader to the terminology most used in everyday speech (first)and then gradually inform him or her what all the other alternate words are. "Ascorbic acid" is definately not used as much as the term "vitamin C", right?

W. Whitney

It's definitely used more. Not only is it the actual substance (common) name, but it's what is listed in prepared food ingredients. --Belg4mit 17:22, 21 May 2007 (UTC)

The acid hydrolysis mechanism here uses single-headed arrows. This is wrong. A single-headed arrow implies movement of single electrons (a radical mechanism). Double headed arrows should be used here, implying movement of electron pairs. 24.181.29.106



Ascorbic acid and Vitamin C are not equivalent--Vitamin C is a form of ascorbic acid (I'm believing what I'm reading). Ascorbic acid is more general, so if anything, Vitamin C should redirect into ascorbic acid.

However, I think it's best if they're separate entries; ascorbic acid about the general class of ascorbic acid, Vitamin C about the L-idoslkwhater of ascorbic acid.

--TheCunctator


Exactly. isomer. The L isomer. Althought that isn't the only nomenclature that can be used to describe the isomeric differences. I'm not an expert on the biochemistry of ascorbic acid--it could be that the L form and the D form interconvert to form a racemate in vivo, but I wouldn't bet on it.

one can discuss ascorbic acid as a organic acid without any reference to it as a nutrient. That's why I originally put the stuff in about it's use as a reductant in chemical developer solutions--Eastman Kodak uses tons of this stuff!

--JoeAnderson


Was it Haworth or Szent-Györgyi who got the Nobel for vitamin C? -- Marj Tiefert, Tuesday, June 11, 2002


both!

see:

http://www.nobel.se/chemistry/laureates/1937/haworth-lecture.html

http://www.nobel.se/medicine/laureates/1937/szent-gyorgyi-lecture.html

Malcolm Farmer, Wednesday, June 12, 2002


Could someone check my revision of the SMILES string? I didn't like how it neded with (CC) since I don't see an ethyl in the structure anywhere.

C1(O)=C(O)C(=O)OC1(C(O)CO)

gives the same structure as "ascorbin.gif" when I plug it in at http://www.daylight.com/daycgi/depict, although my head swims when I try to figure it out on paper. Milkfish 11:25 Apr 14, 2003 (UTC)


Fundermetaly... Vitamin C that we commonly know must have called L-ascorbic acid. That is ascorbic acid include ascorbic acid. -From my tiny knowledge- Moon Empress 2010.06.21 —Preceding unsigned comment added by 211.182.212.129 (talk) 09:15, 21 June 2010 (UTC)


  • Note that since Erythorbic acid and Ascorbic acid are stereoisomers, they differ among at least one of their two chiral centres; however, the images on both pages are identical. Which of the two images is correct? Can someone please look it up and post the correct image?

Many (most?) bird species do not require vitamin C, so I changed "birds" to "some birds" on the article page. See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3145266/ Rex senegalus (talk) 17:24, 29 January 2014 (UTC)


Molecular weight ?[edit]

An anonymous user amended this from 176.12 to 176.13 Both weights give a similar number of hits on Google however since a large proportion of the 176.12 sites are Wikipedia mirror ones I've left the higher figure. Can anyone give an authorative answer? Lumos3 15:33, 26 Sep 2004 (UTC)

Using the numbers for atomic weight given on wikipedia for carbon (12.0107), Hydrogen (1.00794), and Oxygen (15.9994), it's 176.12412, which would be the same as 176.12, so I edited it back. --Niffux 06:43, 20 Oct 2004 (UTC)

Synthesis route?[edit]

I know nothing on this, but would like to see a section on how it's synthesized, and when that process was developed etc. Thanks!--Joel 02:53, 25 Apr 2005 (UTC)

There is a short description of Artificial chemical synthesis on Vitamin C#Sources. But a more detailed chemistry based description would be welcome here. Lumos3 08:10, 25 Apr 2005 (UTC)

There is mention of GE bacteria being used. Are there any references to this please?


Which is the "acid" hydrogen?[edit]

I'm curious since the molecule doesn't have any obvious "acid" component. Does the ring get hydrolyzed, leaving a carboxyl group? GCarty 08:57, 18 July 2005 (UTC)

--- While the acidic hydrogen is currently noted, I am not in agreement with how it is exemplified. Ascorbic acid is a vinylogous acid. That is it has a double bond added between the carbon and oxygen of a simple acid like acetic acid. I do not disagree with the arrows showing why the carbonyl oxygen pulls the electrons of the sp3-oxygen in and thus increasing the proton-electron pair distance, thus increasing its acidity. However, for simplicity, I would prefer a more conventional description in which the proton is removed to give a vinylogous acid with the negative charge distributed over both oxygen atoms in a traditional resonance arrow to separate the two resonance structures. Orgopete 12:42, 18 April 2007 (UTC)


This is not directly within the acid hydrogen discussion, but I am unfamiliar with contributing to a wiki, so please excuse my ignorance. The tautomerism discussion is really an extension of the vinylog acidity in that the negative charge of the anion can reside on three atoms. Therefore, protonation can logically also occur on any of the three, including on the carbon. However, that isomer is less stable than the common structure on the page. In the tautomerism discussion, it describes the formation of the 1,2-diketone being able to form, and I think that would be the more interesting isomer to show it formation as my above discussion shows, yet the 1,2-diketone is not illustrated. Since it is simply related to the given mechanism, I suggest the formation of the 1,2-diketone preferentially or additionally be shown. Orgopete 12:56, 18 April 2007 (UTC)


Is there any empirical evidence for the existence of the C2- or C3- protonated tautomers? There is no reference in this section. Absent citation of some evidence, I think this discussion should be deleted. It has no practical relevance to understanding actual ascorbic acid or its properties. Rectifico (talk) 18:11, 17 June 2010 (UTC)

To Polyparadigm and GCarty[edit]

Polyparadigm- I do have infomation on the synthesis of Vitamin C in about 10 different methods, though im not really sure about copyright on the images i would need to explain it.
GCarty - The OH groups on the 'bottom' of the molecule are easily oxidised and the H+ are dissociated into solution, giving the acid, acidic preoperties. (usually only 1 H+ dissociates forming dehydroascorbic acid, therefore its is only a weak acid) the remaining oxygen form a double bonds with the carbon (a carbonyl group like you mentioned)
(Eyehawk78 23:43, 1 March 2006 (UTC))


The acid is the OH on the very last of the string, but not any part or near the ring.

Decomposition of ascorbic acid[edit]

I read somewhere (don't remember where) that vitamin C decomposes with heat. Is this true? (I can't find anything on it on this article so if it's there point me to it.)

If so, does vitamin C continue to decompose while it's at a constant heated temperature (like, heated to 50 degrees C and then kept at 50 degrees C)? And what's the equation for its decomposition?

(I am studying chemistry at senior secondary school level (equivalent to 16-18 year olds).) Neonumbers 10:12, 27 March 2006 (UTC)

Decomposition?
At 50°C with oxygen present you get from HO-C=C-OH at the 5membered ring to the oxidated state of O=C-C=0 there this is the reaction normaly ascorbic acid is used for an anti oxidant protecting other substances to be oxidized, by being oxidized.--Stone 10:28, 27 March 2006 (UTC)

So ascorbic acid doesn't decompose, but instead gets oxidised by oxygen? (Ignore the "50 degrees" and replace 50 with some higher number if necessary.) Then (just so I can grasp everything):

  • could I ask someone please to elaborate on the melting point "190 - 192°C (decomposes)"?
Merk calaloug says the same.
  • does that mean that if you put ascorbic acid in a closed bottle without any oxidant in it, nothing will ever happen to it no matter how heated it is (practical considerations aside)?
No! Acid esters with alkohols can give reactions and it contains both groups. The temperature is the point 50°C would be OK but for some time but every 10°C the reaction rate doubles and at this rate with 100-150°C the stuff will turn brown and black within the hour.
Other reactions then oxidation like ester cleaving is also possible!
  • does that mean that heating something with vitamin C merely speeds up the rate of reaction, or shifts an equilibrium, of the redox reaction, or something on the lines of thermochemical/equilibrium principles?
speed up with temperatur!
  • is ascorbic acid oxidised by oxygen at room temperature (albeit slowly)?
Yes slowly!

Perhaps now is a good time to explain the context of my question: I am planning to investigate the effect of heat on the concentration of ascorbic acid in blackcurrant juice. Neonumbers 12:11, 27 March 2006 (UTC)

May be there is more (papers!)--Stone 16:45, 27 March 2006 (UTC)

Merger with vitamin c[edit]

Oppose This has already been discussed at length see Talk:Vitamin C#Ascorbic Acid vs Vitamin C. Lumos3 19:04, 25 June 2006 (UTC)

The vitamin C article is already plenty long, breaking it into a basic and industrial chemistry article and a separate, more biological one is fine. Also all vitamin C related material is not strictly ascorbic acid alone. Opposed.--69.178.41.55 06:44, 28 June 2006 (UTC) see prior discussion at Talk: Vitamin C late 2005.

3 weeks in the sun (5 to 7 days as a decent comment interval, 4-0) with no support, I removed the Merger proposal tags.--69.178.41.55 05:49, 16 July 2006 (UTC)

Oppose for reasons stated above BrianZ(talk) 05:35, 2 July 2006 (UTC)

Oppose, ditto. -- Hongooi 10:43, 2 July 2006 (UTC)

Strong Oppose as above.--TheNautilus 07:27, 1 February 2007 (UTC) ṆјĽÈŲˡΑþŞΞĹ[[Category:]]

I'd like to suggest cross-linking the two articles in the heading in a bit bolder manner. -- Anonymous 07:20 13 Apr 2010 (MDT)

Strong Oppose as above. Each is already listed as main article of the other. The only way to more strongly cross link would be a "differentiate" template right at the beginning of each article. SBHarris 02:59, 8 June 2010 (UTC)

I removed the Merge with Vit C flag, as the consensus is that they should stay separate articles. 5Q5 (talk) 17:52, 7 July 2010 (UTC)

Merge Erythorbic acid into this article?[edit]

Articles such as Tartaric acid contain stereoisomer information rather than having it in separate articles. This would probably be the best idea here.

  • Support §ĉҺɑʀκs 13:06, 16 December 2006 (UTC)
  • Support Lumos3 14:58, 16 December 2006 (UTC)
  • Support: I agree, but don't take me too seriously because I'm not a chemist. Neonumbers 12:31, 17 December 2006 (UTC)
  • Oppose Although the chemistry and industrial uses of Erythorbic acid are very simular to ascorbic acid or vitamin C, it took me, as a PhD chemist, about ten minutes and the use of the Acros Organic Catalogue (which I just accidently happen to have on my desk), to reveal the difference between the two compounds. This means, by transfering the Erythorbic acid article, to the ascorbic one, the erythorbic data rappidly drawn in the ascorbic. On the other hand, by focusing on the differences in the erythorbic-article and refering to ascorbic acid on the chemical behavior both points of view may be satisfied. T.vanschaik 22:14, 17 December 2006 (UTC)
    The Eryhthorbic acid article's not that long. How about having it in a section or sub-section in this article? Then those differences can be focused on there. Neonumbers 02:01, 18 December 2006 (UTC)
  • Oppose Since there are vitamin, essential food and pharmaceutical uses of ascorbic acid, food antioxidant use of erythorbic and a strong industrial use of erythorbic, I prefer to try to maximize separation to avoid possible confusion. The erythobic acid article needs room to grow.--TheNautilus 07:27, 1 February 2007 (UTC)
  • Oppose - distinct chemical compounds Jack · talk · 03:01, Monday, 26 February 2007
  • Oppose - they're stereoisomers all right, but diastereomers, not enantiomers. Diastereomers of cyclic compounds have different chemical reactivity even in an achiral environment. Furthermore, their interconversion is not tautomeric. Similar example: glucose and mannose. --Vuo 18:14, 21 May 2007 (UTC)

Stereoismerism[edit]

Why is there nothing in the article about L-ascorbic acid and D-ascorbic acid? I mean it is a big deal, two totally distinctly different seperate sides of Ascorbic Acid, and there's nothing about this in the article... Like how research shows the body disregards D-ascorbic acid (+) and only uses L-ascorbic acid (-). Or at least anything regarding the 2 different and seperate sides of ascorbic acid. Does anyone think something regarding this topic should be put in the article?

I agree the optical isomerism of the molecule should be in there sonmewhere. Lumos3 (talk) 23:27, 15 April 2010 (UTC)

The image of ascorbic acid may show the wrong stereochemistry. Here's why:

  • Since Erythorbic acid and Ascorbic acid are stereoisomers, they differ among at least one of their two chiral centres. However, the images on both pages are identical. Therefore, one MUST be wrong. Which of the two images is correct? Can someone please look it up and post the correct image?

The two images File:Erythorbic acid.png and File:L-Ascorbic_acid.svg are not identical, they just look similar until you pay close attention.

Ascorbic-acid-vs-erythorbic-acid-2D-skeletal.png

Ben (talk) 17:05, 5 April 2011 (UTC)

Specifically, the two figures have the same chirality at the chiral center in the ring, and the opposite at the other (exocyclic) chiral center. It is the chiral center farthest from the aldehyde, which in this case is the exocyclic center, that determines D and L. Since D and L isomers are complete mirror images, D-ascorbate would differ from L-ascorbate at both centers. Now take D-ascorbate and invert the ring chiral center (so that it is the same as in L-ascorbate) and you have D-erythorbate. It might be mentioned on the erythorbate page that this is the D stereoisomer. However apparently erythorbate is readily available only as the D isomer, and ascorbate as the L (at least from Sigma) presumably because they are derived from readily available natural materials.Eaberry (talk) 23:33, 20 March 2012 (UTC)


Pronunciation?[edit]

Do you pronounce Ascorbic acid "uh-sore-bic" or "uh-score-bic"? In other words, is the "c" silent?? -52.128.30.25 14:04, 8 August 2007 (UTC)

Benzene from Benzoic acid in a can of soda??[edit]

Benzene_in_soft_drinks

Any idea what the reaction mechanism behind that one is? Evidently its not anything that goes anywhere near completion, but it made enough benzene to make news, apparently. Zaphraud (talk) 00:22, 20 March 2009 (UTC)

Ascorbic acid as a swimming pool stain eradicator[edit]

If you've got those brown stains in your pool, ascorbic acid makes it go away like magic. —Preceding unsigned comment added by Menshadow (talkcontribs) 04:26, 13 April 2009 (UTC)

Missing oxygens in resonance diagrams?[edit]

Is it just me, or are the resonance diagrams in the acidity section missing an oxygen? Looks like only five are shown, and shouldn't there be six? —Preceding unsigned comment added by Ehb (talkcontribs) 15:21, 15 October 2009 (UTC)

Hi, yes, you're right, there is one oxygen atom missing in each molecule. I'm sorry, I can't fix that (wikipedia beginner), could someone else please take care of it? JaninaM (talk) 13:37, 6 January 2010 (UTC)
If you are talking about File:AscorbicAcid acidity.svg, it appears to be correct to me. There are six oxygen atoms in each molecule. Maybe it was wrong at some point, but I just wanted to point out that it is now correct. ChemNerd (talk) 15:26, 1 March 2012 (UTC)

UV Vis spectra[edit]

anyone have UV vis spectra of VitC and degradation compounds (the brown, smelly things that form when solutions exsposed to air ? (I assume vitC by itself has no vis absorbance, since solutions are clear, and that UV may be generic, as there are no conjugated systems of note) — Preceding unsigned comment added by 68.236.121.54 (talk) 14:58, 1 March 2012 (UTC)

Ascorbic Acid Made By Boiling Corn Syrup in SuLphuric Acid?[edit]

I doctor told me that ascorbic acid or vitamin C is made by boiling corn syrup in suLphuric acid. If there is truth to this it needs to be explained in the article. 2602:306:C518:62C0:69B8:B150:2C54:4E9F (talk) 14:02, 19 August 2012 (UTC)

L- and D- not explained[edit]

The article statues that

   "There exists a D-ascorbic acid"

without any explanation of what that means. I gave up chemistry several decades ago, and would (have) appreciate(d) a hint/reminder of what is going on.

Looking on THIS page, I think it is related to being a different isomers. So something as simple as....

   "There also exists D-ascorbic acid, a stereoisomer of the XXX L-ascorbic acid."

where XXX should be something like "better known", "more common", "first discovered", "more important".... And, of course, Stereoisomer should be a link to the relevant page/article...

RobertII (talk) 13:04, 14 July 2014 (UTC)