ACD/Sigma
Quickly calculate the electronic substituent constant sigma (σ), for selected fragments of your molecule or substituents of your library.
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Do you have a hunch that you can correlate some observed behavior of your series of compounds with their Hammett constants?
ACD/Sigma allows you to directly access the electronic substituent constant (σ), for any desired substituent, which is attached to the reaction center by a single bond and whose point of attachment is shown with an R-label. The sigma query will be executed at a click of a button!
A common request we receive from researchers and academics is for the actual value of the electronic substituent constant. Here's why:
- Correlation with new properties—the σ-based structure-property relationship has been remarkably successful for chemists for the past half-century.
- Library design—knowledge of Hammett sigma constants is extremely helpful in designing an effective parallel synthesis.
- Pedagogical purpose—the Hammett equation is in the core curriculum of every undergraduate organic chemistry program. ACD/Sigma is a novel teaching tool demonstrating the concept of σ. And in the lab, it will be useful in evaluation of the underlying patterns while choosing a chemical substituent.
ACD/Sigma is available as a part of ACD/PhysChem Suite which includes the full range of ACD/Labs physicochemical and molecular property predictors including logP, logD, pKa, aqueous solubility, boiling point and more.
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