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Updated: Dec 31, 2025
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Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
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A Nuclear Magnetic Resonance and Relaxation Study of Dimethoxyborane
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Summary
Nuclear magnetic resonance (NMR) studies reveal insights into molecular dynamics in solid and liquid phases of H11B(OCD3)2 and H10B(OCD3)2. Key findings include quadrupolar coupling constants and activation energy for molecular reorientation.
Area of Science:
- Solid-state and liquid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
- Physical Chemistry and Molecular Spectroscopy.
Background:
- Investigating molecular structure and dynamics is crucial for understanding chemical behavior.
- Nuclear magnetic resonance (NMR) spectroscopy provides powerful tools for probing molecular environments.
Purpose of the Study:
- To investigate the solid-state and liquid-state properties of H11B(OCD3)2 and H10B(OCD3)2 using NMR.
- To determine the quadrupolar coupling constant and activation energy for molecular reorientation.
Main Methods:
- Continuous wave (c.w.) proton and boron-11 NMR spectroscopy on solid samples.
- Nuclear magnetic relaxation studies on liquid samples at various frequencies.
- Analysis of spectral line shapes and relaxation times.
Main Results:
- Determined the quadrupolar coupling constant for 11B to be 3.0 ± 0.2 MHz in the solid state.
- Observed distinct proton line shapes in H10B(OCD3)2, suggesting changes in nuclear quantization.
- Calculated the activation energy for molecular reorientation as 8.7 ± 0.4 kJ/mol from 10B and 11B relaxation times.
- Obtained consistent quadrupolar coupling constants from both solid-state and liquid-state measurements.
- Proton relaxation times showed deviations from the activation energy model at higher temperatures, indicating spin-rotation interactions.
Conclusions:
- NMR spectroscopy effectively characterizes molecular dynamics and interactions in different phases.
- The study provides valuable data on the physical and chemical properties of boron-containing compounds.
- Further investigation into spin-rotation interactions is warranted for a comprehensive understanding of proton relaxation.
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