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Related Concept Videos

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Stereoisomerism of Cyclic Compounds

In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
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Distillation is a separation technique that takes advantage of the boiling point properties of disparate elements in a mixture. To perform distillation, we begin by heating a miscible mixture of two liquids with a significant difference in boiling points (at least 20°C). As the solution heats up and reaches the bubble point of the more volatile component, some molecules of the more volatile component transition into the gas phase and travel upward into the condenser, which is a glass tube with...
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Vanillin—a flavoring agent in vanilla, cinnamaldehyde—a molecule responsible for the distinct smell of cinnamon, and acetone—a strong-smelling ingredient in nail polish removers, all belong to a class of carbonyl compounds called aldehydes and ketones (Figure 1). Although both aldehydes and ketones contain the characteristic carbonyl (C=O) bond, their chemical structures vary with respect to the groups directly attached to the carbonyl carbon.
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UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...

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HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin
11:15

HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin

Published on: July 23, 2016

Conformational equilibria in vanillin and ethylvanillin.

Emilio J Cocinero1, Alberto Lesarri, Patricia Ecija

  • 1Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV-EHU), Apartado 644, E-48080 Bilbao, Spain. emiliojose.cocinero@ehu.es

Physical Chemistry Chemical Physics : PCCP
|August 20, 2010
PubMed
Summary

Rotational spectroscopy revealed two distinct conformers for vanillin and ethylvanillin, stabilized by intramolecular hydrogen bonds. Computational methods supported these findings, detailing conformational landscapes and rotation barriers.

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Area of Science:

  • Physical Chemistry
  • Molecular Spectroscopy
  • Computational Chemistry

Background:

  • Vanillin and ethylvanillin are aromatic aldehydes with potential for diverse molecular conformations.
  • Understanding molecular conformation is crucial for predicting chemical properties and reactivity.

Purpose of the Study:

  • To investigate the conformational equilibria of vanillin and ethylvanillin.
  • To characterize the specific conformers present and the factors influencing their stability.

Main Methods:

  • Rotational spectroscopy in a supersonic jet expansion.
  • Ab initio (MP2) and Density Functional Theory (DFT) calculations (B3LYP, M05-2X).

Main Results:

  • Two conformers were identified for both vanillin and ethylvanillin, primarily dictated by an O-H···O intramolecular hydrogen bond.
  • Vanillin conformers differed in aldehyde group orientation (cis/trans); ethylvanillin showed planar ethoxy trans arrangements, with gauche forms likely absent due to jet relaxation.
  • Internal rotation barriers for methyl groups were estimated to be above 12.3 kJ mol⁻¹, with no detectable torsional tunneling effects.

Conclusions:

  • The dominant O-H···O hydrogen bond significantly influences the conformational landscape of vanillin and ethylvanillin.
  • Supersonic jet expansion and computational chemistry provide complementary insights into molecular structure and dynamics.
  • The study elucidates the conformational preferences and rotational barriers of these important flavoring compounds.