Understanding Amino Acid Acidity and Basicity in Reactions

In summary, the two reactions discussed demonstrate the behavior of an amino acid as both an acid and a base. In the first reaction, the amino acid acts as an acid by donating a proton to form an ester. In the second reaction, it acts as a base by accepting a proton to form an amide. However, the concept of an ester as a product of an acid-alcohol reaction is not always accurate and may vary depending on the mechanism. The second reaction may not necessarily demonstrate basic behavior, and the question itself may be questionable.
  • #1
jsmith613
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Homework Statement



How does the following reaction demonstrate an amino acid as an acid:
H2NCH2COOH + CH3OH → H2NCH2COOCH3 + H2O

How does the following reaction demonstrate an amino acid as a base:
H2NCH2COOH + CH3COCl → CH3CONHCH2COOH + HCl

Homework Equations





The Attempt at a Solution


An acid is a species that DONATES a proton and a base is a species that ACCEPTS a proton

In both situations it seems more like an esterfication reaction than an acid / base reaction.

Also in the second reaction the H2N loses an H+ for water (I would call that acidic behaviour but it is actually basic behaviour) and the first example COOH loses OH (basic behaviour but is classified as acidic)

I am confused :S
 
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  • #2
This is not about a standard Bronsted acid definition. Think outside of the box. What is an ester?

That's what they ask about, doesn't mean I like the question.
 
  • #3
Borek said:
This is not about a standard Bronsted acid definition. Think outside of the box. What is an ester?

That's what they ask about, doesn't mean I like the question.

well an ester is a type of condensation reaction in which a small molecule is eliminated?
 
  • #4
No, ester is not a type of a reaction. It is a product of a reaction. Reaction of what with what?
 
  • #5
Borek said:
No, ester is not a type of a reaction. It is a product of a reaction. Reaction of what with what?

a carbonyl carbon (e.g: COOH or COCl) and a hydrogen attached to an electronegative atom (e.g: OH, H2N)
 
  • #6
In fact another site says its when the hydrogen of an organic acid is replaced by an organic group (e.g: alkyl)

BUT the acid LOSES OH not just the H?
 
  • #7
The other site is wrong. That is, it is wrong when you look at the mechanism, but it is OK when you look just at the product structure.

Ester is produced by a reaction of an acid (even doesn't have to be organic - think sulfuric, phosphoric) with an alcohol.
 
  • #8
Borek said:
The other site is wrong. That is, it is wrong when you look at the mechanism, but it is OK when you look just at the product structure.

Ester is produced by a reaction of an acid (even doesn't have to be organic - think sulfuric, phosphoric) with an alcohol.

ok so I get the first one but how does the second rxn demonstrate basic behaviour?
 
  • #9
To be honest - I don't see how. I told you I don't like the question.
 
  • #10
Borek said:
To be honest - I don't see how. I told you I don't like the question.

nm
thanks for your help :)
 

1. What are amino acids and why are they important in reactions?

Amino acids are organic compounds found in living organisms that serve as the building blocks of proteins. They are important in reactions because they can act as both acids and bases, allowing them to participate in a wide range of chemical reactions.

2. How do amino acids exhibit acidity and basicity in reactions?

Amino acids contain both acidic and basic functional groups. The carboxylic acid group (COOH) is acidic and can donate a proton, while the amino group (NH2) is basic and can accept a proton. This allows amino acids to exhibit both acidic and basic properties in reactions.

3. What determines the acidity or basicity of an amino acid?

The acidity or basicity of an amino acid is determined by the side chain, or R group, attached to the central carbon atom. Side chains with acidic functional groups, such as carboxyl or sulfhydryl groups, make the amino acid more acidic, while basic side chains, such as amino or guanidino groups, make the amino acid more basic.

4. How does the pH of a solution affect the acidity or basicity of amino acids?

The pH of a solution can greatly affect the acidity or basicity of amino acids. At low pH, the carboxylic acid group will be protonated and the amino group will be deprotonated, making the amino acid more acidic. At high pH, the opposite will occur, making the amino acid more basic.

5. What are some common reactions involving amino acids?

Amino acids can participate in a variety of reactions, including condensation reactions to form proteins, acid-base reactions to form salts, and redox reactions to form disulfide bonds. They can also undergo decarboxylation and transamination reactions to form other amino acids or metabolic products.

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