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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: itunu on August 11, 2015, 01:18:10 PM

Title: carboxylic acid
Post by: itunu on August 11, 2015, 01:18:10 PM
I have a pretty stupid question regarding the structure of carboxylic acid.
Why is written COOH rather than OCOH ??  The double bond is between the O and C. 
COOH implies there are two O joined together but this isn't the case.
Title: Re: carboxylic acid
Post by: itunu on August 11, 2015, 01:35:35 PM
btw I have read the rules and I have searched for the answer to no avail.  I then asked people with chemistry degrees and was told "It's just a chemistry notation thing." and "it's a habit" but that still leaves me confused.
Title: Re: carboxylic acid
Post by: Arkcon on August 11, 2015, 02:35:18 PM
Conceptually, I like your notation better, and I may start using it.  However, it could add to confusion when drawing -COOH as part of another molecule.  Then you're implying the molecule binds to the O and not the C.  Still, just a convention, really.
Title: Re: carboxylic acid
Post by: itunu on August 11, 2015, 02:44:15 PM
Thank you Arkcon, I'm glad it wasn't a stupid question after all !
Title: Re: carboxylic acid
Post by: Corribus on August 11, 2015, 02:54:45 PM
I have a pretty stupid question regarding the structure of carboxylic acid.
Why is written COOH rather than OCOH ??  The double bond is between the O and C. 
COOH implies there are two O joined together but this isn't the case.
Just as easily, R-OCOH could be taken to imply R-O-C-OH, equally wrong. Using this kind of notation, either way could imply an incorrect structure. A better way would be C(=O)OH, but this is cumbersome. COOH or CO2H has been used long enough that people understand what it means most of the time. Carboxylic acids are more common than peroxides, so it's usually not a problem, and there is usually context as well to help out.
Title: Re: carboxylic acid
Post by: Babcock_Hall on August 15, 2015, 03:12:47 PM
One problem I have seen when abbreviating a carboxylate group as R-CO2- is that when students wish to show carbon dioxide as a product, they write it as CO2-, which is obviously wrong.