In the precise world of chemical synthesis and pharmaceutical development, the rigorous characterization of intermediates is non-negotiable. 3-Bromophthalide (CAS 6940-49-4) is a key compound whose reliable use depends on understanding its structure and confirming its purity. At NINGBO INNO PHARMCHEM CO.,LTD, we employ advanced analytical techniques to ensure the quality of our 3-Bromophthalide, and this article highlights the essential methods used for its thorough characterization.

Understanding the molecular identity and purity of a chemical is crucial for reproducible results in any synthetic endeavor. This involves a combination of spectroscopic methods that probe the molecule's interaction with electromagnetic radiation and computational approaches that predict its properties based on theoretical models.

Spectroscopic Techniques for Structural Elucidation and Purity Assessment

Nuclear Magnetic Resonance (NMR) spectroscopy is the cornerstone of structural determination for organic molecules. For 3-Bromophthalide, both proton NMR (¹H NMR) and carbon-13 NMR (¹³C NMR) provide invaluable information.

  • ¹H NMR Spectroscopy: The proton NMR spectrum reveals the number and types of hydrogen atoms in the molecule. Typically, the aromatic protons on the phthalide ring appear as distinct signals in the downfield region (around 7.5-8.0 ppm). The key methine proton attached to the carbon bearing the bromine atom (at the 3-position) usually presents as a singlet, allowing for straightforward identification.
  • ¹³C NMR Spectroscopy: Carbon-13 NMR provides information about the carbon skeleton. The lactone carbonyl carbon is observed at a characteristic downfield shift (around 167-170 ppm), while the carbons within the aromatic ring and the carbon attached to bromine resonate at different positions, confirming the molecule's framework.

Infrared (IR) spectroscopy is another vital technique that identifies functional groups. The presence of the lactone carbonyl group in 3-Bromophthalide is indicated by a strong absorption band in the IR spectrum, typically around 1750-1780 cm⁻¹. Additionally, absorptions related to the aromatic ring and the carbon-bromine bond provide further structural confirmation.

For assessing the purity of 3-Bromophthalide, High-Performance Liquid Chromatography (HPLC) coupled with UV detection is commonly employed. HPLC separates components based on their different affinities for a stationary phase, allowing for the quantification of the main product and the detection of any impurities. A high purity level, often exceeding 98% or 99%, is typically required for pharmaceutical and fine chemical applications.

Computational Chemistry: Predicting and Confirming Properties

Complementing experimental spectroscopy, computational chemistry offers powerful tools to predict and understand molecular properties. Density Functional Theory (DFT) calculations can model the geometry, electronic structure, and vibrational frequencies of 3-Bromophthalide.

  • Geometry Optimization: DFT calculations can determine the most stable molecular conformation, providing precise bond lengths and angles.
  • Vibrational Analysis: Theoretical IR and Raman spectra can be computed and compared with experimental data, aiding in the assignment of specific vibrational modes and confirming structural integrity.
  • Electronic Structure: Analysis of frontier molecular orbitals (HOMO-LUMO gap) and electrostatic potential maps helps in predicting the molecule's reactivity and interaction potential.

These computational insights validate the experimental findings and can guide further investigations into the compound's behavior and potential applications. NINGBO INNO PHARMCHEM CO.,LTD leverages these advanced characterization methods to ensure that every batch of 3-Bromophthalide meets the highest standards of quality and reliability, supporting your critical research needs.