Questions and Answers
What are the physicochemical properties of drug molecules important for?
Product development and studies on biological performance of drugs.
What is optical rotation also known as?
Polarization rotation.
What term describes a compound that rotates polarized light clockwise?
What is circular dichroism a manifestation of?
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Which device is used to measure optical rotation?
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Optical activity can be observed in fluids only.
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Match the following substances with their optical rotation direction:
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The angle of rotation is calculated by Biot's formula: [α] = (αo) / (c x l), where [α] = specific rotation in degrees, α0 = observed rotation in degrees, c = concentration in g/mL and l = ______.
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Study Notes
Physicochemical Properties of Drug Molecules
- Physicochemical properties are crucial for drug product development and biological performance studies.
- Requires understanding for pre-formulation, formulation development, and storage optimization.
Optical Rotation
- Optical rotation refers to the rotation of polarized light as it passes through optically active substances.
- Dextrorotatory substances rotate polarized light clockwise; laevorotatory substances rotate it counterclockwise.
- Circular birefringence and circular dichroism are manifestations of optical activity.
Measurement of Optical Rotation
- Specific rotation calculated using Biot's formula:
- [α] = (α₀) / (c × l)
- [α] = specific rotation (degrees)
- α₀ = observed rotation (degrees)
- c = concentration (g/mL)
- l = path length (dm)
Characteristics of Optically Active Substances
- Optical activity arises in chiral materials, characterized by asymmetric molecular structures.
- Gases, solutions of chiral molecules (e.g., sugars), and certain solids (e.g., quartz crystals) can exhibit optical rotation.
Applications and Measurement Tools
- Polarimeters are utilized to measure optical rotation in drug molecules.
- Sodium vapor lamps commonly provide the light source for optical rotation measurements, emitting wavelengths above 450 nm.
- Filters convert polychromatic light to monochromatic light for accurate measurements.
Components in Optical Rotation Measurement
- Sample cells are long glass tubes designed to contain the liquid or solution being tested.
- A Nicol prism serves as the analyzer to determine the rotation direction of polarized light.
- Photomultiplier tubes detect the wavelength after light passes through the sample and analyzer.
Bond Dipole Moment
- A bond dipole moment quantifies the polarity of chemical bonds, indicating separation of positive and negative charges.
- It is a vector quantity characterized by both magnitude and direction.
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Description
Explore the fundamental physicochemical properties of drug molecules and their significance in product development. This quiz delves into the reactions that lead to the interconversion and modification of functional groups, highlighting key concepts in pharmaceutical chemistry.
