Theoretical ξr of a molecule from the absolute configuration

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SUMMARY

The discussion focuses on calculating the theoretical relative permittivity (ξr) of organic molecules using accessible theoretical configurations and values. Participants highlight the importance of matching solvent polarity to the solute's ξr to avoid adverse interactions during reactions. Key techniques mentioned include the Clausius-Mossotti relation for deriving molecular polarizability and the Gladstone-Dale relation for approximating permittivity in the optical range. The conversation emphasizes the need for experimental validation, as no quick methods exist for accurate permittivity calculations.

PREREQUISITES
  • Understanding of relative permittivity (ξr) and its significance in solubility.
  • Familiarity with the Clausius-Mossotti relation for calculating molecular polarizability.
  • Knowledge of the Gladstone-Dale relation for estimating permittivity in optical contexts.
  • Basic concepts of inductive effects and charge variance in organic chemistry.
NEXT STEPS
  • Research the Clausius-Mossotti relation and its application in calculating molecular polarizability.
  • Explore the Gladstone-Dale relation for approximating permittivity in organic solvents.
  • Investigate ab initio programs capable of calculating molecular polarizability.
  • Study the role of magnetic susceptibility in relation to permittivity and solubility.
USEFUL FOR

Chemists, particularly those in pharmaceutical research and organic chemistry, will benefit from this discussion as it provides insights into solvent selection based on theoretical permittivity calculations.

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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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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In the optical range this is possible in some approximation. Look up Gladstone - Dale relation.
 
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