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Specific Rotation Calculation


Light is an electromagnetic wave, and its vibration direction is perpendicular to its forward direction. Light waves of ordinary light can vibrate on various planes. If ordinary light passes through a Nicol prism or an artificial polarizer, only the light whose vibration direction is parallel to the crystal axis of the prism can pass and this kind of light that only vibrates on one plane is called plane polarized light. When plane polarized light passes through a solution containing a certain substance, the substance is called an optically active substance if the light is deflected. At a certain wavelength and temperature, the optical rotation produced by polarized light passing through a solution with a length of 1 dm and containing 1 g of optically active substance per 1 ml is called the specific rotation. Specific rotation is an important physical constant of optically active substances which be used to distinguish drugs or determine the content and purity of drugs.

The specific optical rotations of flexible molecules are calculated using density functional theory and correlated with their absolute configurations.Figure 1. The specific optical rotations of flexible molecules are calculated using density functional theory and correlated with their absolute configurations. (Lu, J.; et al. 2020)

Our Specific Rotation Calculation Workflow

We calculate the specific optical rotations of the two chiral molecular configurations to determine the absolute configuration of the molecule. Alfa Chemistry has created an optimized and validated process for specific rotation calculation:

  • Molecular structure optimization

We optimize the structure of a pair of enantiomers.

  • Optical rotation and specific rotation calculation

We then use the optimized molecule in the previous step as the initial structure to calculate the specific rotation of S and R types, and calculate the specific optical rotation.

  • Analysis of calculation results

Finally, we provide the specific rotation of each configuration at different incident wavelengths.

Our Services

  • For flexible molecules, we conduct a comprehensive conformation search and the calculation results are Boltzmann averaged.
  • In order to obtain an accurate calculation result, we conduct a large basis set for calculation.
  • Our scientists fully consider the influence of the solvent to obtain a reliable result of the measurement in the solvent due to the specific rotation is greatly affected by the solvent.

Specific rotation calculation is able to be used to determine the absolute configuration of the molecule. Our specific rotation calculation services remarkably reduce the cost, promote further experiments, and enhance the understanding of chemical process for customers worldwide. Our personalized and all-around services will satisfy your innovative study demands. If you are interested in our services, please don't hesitate to contact us. We are glad to cooperate with you and witness your success!


  • Lu, J.; et al. Specific optical rotation and absolute configuration of flexible molecules containing a 2-methylbutyl residue. European Journal of Organic Chemistry, 2020, 30: 4768-4774.

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