Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Structure of Benzene: Kekulé Model01:07

Structure of Benzene: Kekulé Model

In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
Structure of Benzene: Molecular Orbital Model01:18

Structure of Benzene: Molecular Orbital Model

According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).
NMR Spectroscopy of Benzene Derivatives01:37

NMR Spectroscopy of Benzene Derivatives

Simple unsubstituted benzene has six aromatic protons, all chemically equivalent. Therefore, benzene exhibits only a singlet peak at δ 7.3 ppm in the 1H NMR spectrum. The observed shift is far downfield because the aromatic ring current strongly deshields the protons. Any substitution on the benzene ring makes the aromatic protons nonequivalent, and the protons split each other. The peak is, therefore, no longer a singlet and the splitting pattern and their associated coupling constants depend...
Mass Spectrometry: Aromatic Compound Fragmentation01:23

Mass Spectrometry: Aromatic Compound Fragmentation

Upon ionization, aromatic compounds generate a molecular ion that is observed as a prominent peak in their mass spectra. For example, the molecular ion peak for benzene appears at a mass-to-charge ratio of 78, while toluene is observed at a mass-to-charge ratio of 92. The molecular ion benzene is highly stable and does not readily undergo further fragmentation due to the significant amount of energy required to disrupt the aromatic stability of the benzene ring. In contrast, the molecular ion...
Frost Circles for Different Conjugated Systems01:18

Frost Circles for Different Conjugated Systems

The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.
Mass Spectrometry: Cycloalkane Fragmentation01:05

Mass Spectrometry: Cycloalkane Fragmentation

In mass spectrometry, cycloalkanes exhibit distinct fragmentation patterns due to the inherent stability of their molecular ions compared to linear or branched alkanes. The ring structure of cycloalkanes provides additional stability to the molecular ions, often resulting in prominent ion peaks in the mass spectrum.
For example, cyclohexane molecular ions have a mass-to-charge ratio (m/z) of 84, which tends to produce a stronger signal than linear alkanes like hexane. This stability comes from...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Structure, isomerism, and vibrational assignment of aluminumtrifluoroacetylacetonate. An experimental and theoretical study.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy·2017
Same author

Conformation, molecular structure, and vibrational assignment of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II).

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy·2014
Same author

Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy·2014
Same author

Conformational analysis, intramolecular hydrogen bonding, and vibrational assignment of 4,4-dimethyl-1-phenylpentane-1,3-dione.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy·2013
Same author

Structural, IR, and EPR studies of the bis(methoxyacetato)diaquo-copper(II) complex.

Journal of molecular modeling·2008
Same author

Conformational stabilities, infrared, and vibrational dichroism spectroscopy studies of tris(ethylenediamine) zinc(II) chloride.

Journal of molecular modeling·2008

Related Experiment Video

Updated: Jun 22, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
10:44

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

Spectra and structure of binary azeotropes VI-benzene-methanol.

M R Jalilian1, S F Tayyari

  • 1Department of Chemistry, Faculty of Science, Al-Zahra University, Vanak, Tehran, Iran. jalilianiraj@yahoo.com

Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|May 30, 2009
PubMed
Summary

Benzene and methanol form a minimum boiling azeotrope (2:3 ratio). Azeotrope formation alters vibrational modes and NMR signals, revealing molecular interactions and cluster structure.

More Related Videos

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions
04:38

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Published on: July 28, 2022

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
05:34

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes

Published on: December 16, 2019

Related Experiment Videos

Last Updated: Jun 22, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
10:44

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions
04:38

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Published on: July 28, 2022

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
05:34

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes

Published on: December 16, 2019

Area of Science:

  • Physical Chemistry
  • Spectroscopy
  • Chemical Thermodynamics

Background:

  • Azeotropes are mixtures with constant boiling points, complicating separation processes.
  • The benzene-methanol binary azeotrope exhibits a minimum boiling point at a 2:3 mole ratio.
  • Previous studies lacked detailed spectral analysis (IR, Raman, NMR) of this azeotrope's unit structure.

Purpose of the Study:

  • To investigate the molecular interactions in the benzene-methanol azeotrope.
  • To analyze spectral changes (FTIR, FT-Raman, 1H NMR) upon azeotrope formation.
  • To deduce the unit-structure of the benzene-methanol azeotrope cluster.

Main Methods:

  • Recording FTIR, FT-Raman, and 1H NMR spectra of pure benzene, pure methanol, and their azeotrope.
  • Analyzing spectral shifts and changes in vibrational modes.
  • Correlating spectral data with mole ratio and boiling point depression.

Main Results:

  • Significant changes were observed in specific vibrational modes and 1H NMR signal positions due to azeotrope formation.
  • Mutual influences between benzene and methanol molecules were quantified through spectral analysis.
  • The study provides insights into the intermolecular interactions governing the azeotrope's properties.

Conclusions:

  • The spectral analysis confirms molecular interactions in the benzene-methanol azeotrope.
  • The deduced unit-structure is supported by spectroscopic evidence and thermodynamic data.
  • This research offers a detailed spectroscopic characterization of the benzene-methanol binary azeotrope.