Talk:Carboxylic acid

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Article Grading: The following comments were left by the quality and importance raters: (edit · refresh) Carboxyl group redirects here. Rated "high" as high school/SAT biology content. The article needs a section on biological context, e.g. carboxyl groups on amino acids etc. - tameeria 05:26, 19 February 2007 (UTC)

what is sodium benzoates lewis structure?

Why are you asking something like that on here? This isn't a help page. I don't mean to be rude, but there are better places to post questions like that.

Regarding the flag on the main page. Unless you are planning on having a section on carboxylic acid derivatives (which is not a bad idea), I don't think merging the carbonyl article with this one is a good idea. What about aldehydes, esters, ketones, etc.? Dawhitfield 00:24, 7 August 2005 (UTC)

I think it's about merging with carboxyl, not carbonyl.

There should probably be a section about protecting acids as esters. —Preceding unsigned comment added by 68.10.7.182 (talk) 07:43, 31 March 2008 (UTC)

[edit] Carbonic acid?

Is carbonic acid (HOCOOH) a carboxylic acid? --Damian Yerrick (☎) 02:38, 15 December 2006 (UTC)

Generally no. It is usually considered an inorganic acid. Also, it easily decomposes to CO2 and water. —Preceding unsigned comment added by 68.10.7.182 (talk) 07:40, 31 March 2008 (UTC)

[edit] Polarity

The article says: "Carboxylic acids are polar", and I can understand why, but why is it on certain molecules, adding a carboxylic acid reduces the hydrophilicity / increases the lipophilicity, e.g:

5-hydroxy-tryptamine is fairly polar and can't cross the BBB, and 5-hydroxy-α-carboxyl-tryptamine (5-OH-tryptophan) is fairly non-polar and can cross the BBB.

What is the cause of this? --Mark PEA 19:48, 26 March 2007 (UTC)

It has to do with the presence of both basic and acidic groups within the same molecule. These types of compounds can exist as zwitterions. At some pH, the isoelectric point, the molecules have no net charge and their water solubility decreases (they show more lipophilicity). I hope this helped. Silverchemist (talk) 05:25, 1 April 2008 (UTC)

No, 5-HTP (5-hydroxytryptophan) is extremely polar and cannot cross a lipid barrier. It has actually the highest polarity at the isoelectric point. 5-HTP can cross the blood brain barrier only because there are specialized transporter proteins for it. Сасусlе 06:07, 1 April 2008 (UTC)