No. of stereoisomers in aldol condensation

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In summary, the conversation is discussing the formation of 4 products with a double bond in each of them, resulting in a total of 8 stereoisomers. However, there is confusion about whether delta should be included in the calculation of aldols before dehydration. The question may be unclear as to whether "aldols" refers to all products of the aldol reaction or specifically α,β-unsaturated aldehydes.
  • #1
Physics lover
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Homework Statement
Problem is in attempt at a solution
Relevant Equations
Aldol condensation
Total stereoisomers=##2^n##
where n =no. of double bonds
20191014_133817.png


According to me 4 products will be formed with a double bond in each of them.So total no. of stereoisomers will be=##4×2^1=8##.First product will be formed due self aldol in acetaldehyde.Second will be formed due to self aldol in Propanaldehyde.And the other two will be formed due to mixed aldol.I just want somebody to check my answer.Is it correct?
 
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  • #2
You are right about the double-bond compounds, but the question asks about the number of aldols - implying before dehydration. How many aldols, and how many stereoisomers of each?
 
  • #3
mjc123 said:
You are right about the double-bond compounds, but the question asks about the number of aldols - implying before dehydration. How many aldols, and how many stereoisomers of each?
But they have mentioned delta also.So dehydration should also be there.Otherwise why would they mention delta.
 
  • #4
I don't know, but they say aldols. Unless they use "aldols" to mean "products of the aldol reaction, i.e. α,β-unsaturated aldehydes", which would be sloppy.
 
  • #5
mjc123 said:
I don't know, but they say aldols. Unless they use "aldols" to mean "products of the aldol reaction, i.e. α,β-unsaturated aldehydes", which would be sloppy.
So is it a question fault.Please tell me whether delta should be there or not if they means before dehydration.
 

1. What is an aldol condensation?

An aldol condensation is a type of organic reaction in which an enol or enolate reacts with a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone, respectively. This reaction is commonly used in organic synthesis to form carbon-carbon bonds.

2. How does an aldol condensation produce stereoisomers?

In an aldol condensation, the enolate or enol intermediate can attack the carbonyl compound from either the top or bottom face, resulting in the formation of two possible stereoisomers. This is known as stereoselectivity, and the resulting stereoisomers are known as diastereomers.

3. How many stereoisomers can be produced in an aldol condensation?

The number of stereoisomers produced in an aldol condensation depends on the number of chiral centers present in the reactants. For example, if one of the reactants has one chiral center, two stereoisomers can be produced. If both reactants have one chiral center, four stereoisomers can be produced.

4. How does the addition of a base affect the number of stereoisomers in an aldol condensation?

The addition of a base, such as an amine or hydroxide ion, can increase the number of stereoisomers in an aldol condensation. This is because the base can deprotonate the β-hydroxyaldehyde or β-hydroxyketone product, resulting in the formation of an enolate intermediate. This enolate intermediate can then attack the carbonyl compound from the opposite face, producing an additional stereoisomer.

5. Can an aldol condensation produce enantiomers?

Yes, an aldol condensation can produce enantiomers if the reactants have chiral centers that are mirror images of each other. In this case, the resulting stereoisomers will be enantiomers. However, if the reactants have chiral centers that are not mirror images, the resulting stereoisomers will be diastereomers.

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