Theoretical ξr of a molecule from the absolute configuration

In summary, the conversation discusses the calculation of the theoretical relative permittivity of a molecule using easily accessible values and techniques. It also touches on the use of organic solvents in pharmaceutical reactions and O-chem 2 classes, and the need to find a solvent with a relative permittivity close to that of the compound in question. The conversation also addresses the role of permeability and magnetic susceptibility in these calculations, and the use of optical rotation and the Gladstone-Dale relation in determining polarizability.
  • #1
Jordan M
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I am wondering if anybody knows how to calculate the theoretical relative permittivity of a molecule (1) using the theoretical configuration and values that are easily accessible (2). I am also wondering what the technique would be. In my pharmaceutical reaction class and also O-chem 2 we have been using a variety of organic solvents but they only provide the dielectric constant for solvents, which is the relative permittivity (ξr= ξ/ξο). We are then tasked normally experimentally determining an appropriate solvent based on inductive effects or charge variance with at "matching" the polarity to the ξr value. The trick is to find a solvent that has a ξr that is not too far (+) (-) from our compound in question, as this could cause the solute to interact in a reaction with the solvent. Is there a way to calculate if a molecule will dissolve perfectly in a solvent. Perfectly = [ξr][/1] = ~ [ξr][/2]

Would the permeability or magnetic susceptibility play a role in these calculations?(1)any molecule but specifically looking for answers related to organic molecules, and more specifically looking for examples based off absolute configuration and if optical rotation would play any role)

(2) Values that do not have to be individually experimented to determine.
 
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  • #2
Claudius-Mossotti will get you from permittivity to molecular polarizability, which may or may not be easier to look up for a given species. Most ab initio programs will calculate polarizability. There’s no quick and dirty way I know of to calculate an accurate value for permittivity without doing an experiment.
 
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Likes Jordan M and DrClaude
  • #3
In the optical range this is possible in some approximation. Look up Gladstone - Dale relation.
 

FAQ: Theoretical ξr of a molecule from the absolute configuration

What is the theoretical ξr of a molecule?

The theoretical ξr of a molecule refers to the predicted rotation of polarized light when passing through a solution of that molecule. It is a measure of the molecule's ability to rotate the plane of polarized light.

How is the theoretical ξr of a molecule calculated?

The theoretical ξr of a molecule is calculated using the specific rotation equation: ξr = α/(cl), where ξr is the specific rotation, α is the observed rotation of the polarized light, c is the concentration of the solution, and l is the path length of the light through the solution.

What is the relationship between the theoretical ξr and the absolute configuration of a molecule?

The theoretical ξr is dependent on the absolute configuration of a molecule, as the arrangement of atoms and bonds in a molecule affects its ability to rotate polarized light. Molecules with the same absolute configuration will have the same theoretical ξr value.

Can the theoretical ξr of a molecule be experimentally measured?

Yes, the theoretical ξr can be experimentally measured by passing polarized light through a solution of the molecule and observing its rotation. This value can then be compared to the calculated value to confirm the absolute configuration of the molecule.

What are some factors that can affect the theoretical ξr of a molecule?

Some factors that can affect the theoretical ξr of a molecule include temperature, solvent, and pH. These factors can alter the molecular structure of the molecule, leading to changes in its ability to rotate polarized light.

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