Difference between alpha-keto acid and keto acid

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SUMMARY

The discussion clarifies the distinction between alpha-keto acids and beta-keto acids, emphasizing that alpha-keto acids contain a keto group adjacent to the carboxylic acid (COOH) group, while beta-keto acids have the keto group positioned at the second carbon from the COOH. The concept of alpha and beta carbons is also explored, particularly in the context of cyclic sugars, where the orientation of the hydroxyl (OH) group on the anomeric carbon determines the classification. The discussion references specific examples, including glucose and maltose, and highlights the importance of understanding these terms in organic chemistry.

PREREQUISITES
  • Understanding of organic chemistry fundamentals
  • Familiarity with carboxylic acids and their functional groups
  • Knowledge of cyclic sugar structures and nomenclature
  • Basic grasp of molecular structure representation
NEXT STEPS
  • Research the structural differences between alpha-keto acids and beta-keto acids
  • Learn about the role of anomeric carbons in cyclic sugars
  • Explore the nomenclature conventions for alpha, beta, and gamma carbons in organic compounds
  • Study the implications of alpha and beta configurations in biochemical reactions
USEFUL FOR

Chemistry students, organic chemists, and anyone studying biochemical pathways involving keto acids and sugars will benefit from this discussion.

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Homework Statement


What is the difference between alpha-keto acid and keto acid?

The Attempt at a Solution


I know that the difference is that alpha-keto acid contains an alpha carbon.
However, I do not know what the alpha carbon is in this case, and how I can show it.
 
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What is alpha carbon in other cases?
 
Borek said:
What is alpha carbon in other cases?

You can have alpha carbon, for example, in glucose and maltose.
 
What makes this carbon 'alpha'? Why is it called this way? How does it differ from 'beta'?
 
Borek said:
What makes this carbon 'alpha'? Why is it called this way? How does it differ from 'beta'?

I found the answer in Wikipedia.
Alpha keto-acid has keto group next to COOH, while beta keto-acid has keto group at the second Carbon from COOH.

The LHS molecule is alpha-keto acid, while RHS is beta-keto acid in the following picture.
http://dl.getdropbox.com/u/175564/alpha-beta-acids.png

Note that keto group in the RHS molecule is at the third carbon that is the second C from COOH.

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Is everything correct?
 
Last edited by a moderator:
If you were looking for the answer in wikipedia, it would be better to start at the very beginning:

http://en.wikipedia.org/wiki/Alpha_carbon

soopo said:
The LHS molecule is alpha-keto acid, while RHS is beta-keto acid in the following picture.
http://dl.getdropbox.com/u/175564/alpha-beta-acids.png

Other left.
 
Last edited by a moderator:
Borek said:
If you were looking for the answer in wikipedia, it would be better to start at the very beginning:

http://en.wikipedia.org/wiki/Alpha_carbon

Thank you!

So we have both alpha and beta carbons in both molecules
http://dl.getdropbox.com/u/175564/alpha-beta-carbons-updated.png

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Is the carbons now correctly labeled with alpha and beta carbons?
 
Last edited by a moderator:
OK now.

As you see concept of 'alpha'. 'beta' and 'gamma' carbons is widely used in chemistry. Not very formal, often very useful.
 
Borek said:
OK now.

As you see concept of 'alpha'. 'beta' and 'gamma' carbons is widely used in chemistry. Not very formal, often very useful.

I am unsure about alpha and beta carbons in http://www.laakis.com/wp-content/uploads/2008/12/picture-7.png" .

It seems that the same naming convention does not apply here.
Instead, the position of OH group seems to determine the name.
 
Last edited by a moderator:
  • #10
soopo said:
It seems that the same naming convention does not apply here.

Yes. As I told you - it is not formal. Still, widely used. See GHB for example.
 
  • #11
The alpha and beta conventions for sugars is completely different from the alpha, beta, gamma, etc. nomenclature that you were discussing previously.

For cyclic sugars, alpha refers to a cyclized sugar in which the OH group of the anomeric carbon (the carbon with two bonds to oxygen) is on the opposite side of the ring as the alkyl group on the ring.
 
  • #12
Ygggdrasil said:
The alpha and beta conventions for sugars is completely different from the alpha, beta, gamma, etc. nomenclature that you were discussing previously.

For cyclic sugars, alpha refers to a cyclized sugar in which the OH group of the anomeric carbon (the carbon with two bonds to oxygen) is on the opposite side of the ring as the alkyl group on the ring.

Thank you both!
 

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