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Related Concept Videos

ortho–para-Directing Deactivators: Halogens01:24

ortho–para-Directing Deactivators: Halogens

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Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through the inductive effect and deactivate the aromatic ring towards electrophilic substitution. Halogens also have an electron-donating resonance effect on the ring, which influences the orientation of the incoming electrophile. If an electrophile attacks at the ortho or the para position, the halogen donates electrons and stabilizes the intermediate...
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ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

4.9K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
4.9K
Directing Effect of Substituents: ortho–para-Directing Groups01:14

Directing Effect of Substituents: ortho–para-Directing Groups

6.2K
Ortho–para directors are substituent groups attached to the benzene ring and direct the addition of an electrophile to the positions ortho or para to the substituent. All electron-donating groups are considered ortho–para directors. They donate electrons to the ring and make the ring more electron-rich. The ring is therefore susceptible to the addition of electrophiles. Substituents such as amino, hydroxy, or alkoxy, containing lone pairs on the atom adjacent to the ring, donate...
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Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration02:34

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The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
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Ion Exchange01:17

Ion Exchange

1.5K
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or...
1.5K
Intermolecular Forces03:13

Intermolecular Forces

62.0K
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen...
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Separating para and ortho water.

Daniel A Horke1, Yuan-Pin Chang, Karol Długołęcki

  • 1Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany) http://desy.cfel.de/cid/cmi/

Angewandte Chemie (International Ed. in English)
|September 9, 2014
PubMed
Summary
This summary is machine-generated.

Researchers produced pure beams of para and ortho water, enabling study of their distinct properties and conversion mechanisms. This breakthrough opens new avenues for spectroscopy and spin-enhanced applications.

Keywords:
cold moleculesisomerslaser spectroscopynuclear-spin separationquantum-state selection

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Area of Science:

  • Physical Chemistry
  • Quantum Mechanics
  • Molecular Spectroscopy

Background:

  • Water exists as two nuclear-spin isomers: para-water and ortho-water, distinguished by hydrogen nuclear spin.
  • These isomers are difficult to separate, limiting research into their unique properties and conversion pathways.
  • Current understanding of para- and ortho-water interactions and conversion mechanisms remains limited due to separation challenges.

Purpose of the Study:

  • To demonstrate the production of isolated, pure samples of both para-water and ortho-water.
  • To enable detailed investigation into the physical and chemical properties of each water isomer.
  • To facilitate the study of spin-conversion mechanisms and symmetry-breaking phenomena in water.

Main Methods:

  • Generation of molecular beams containing single-quantum-state para-water.
  • Generation of molecular beams containing single-quantum-state ortho-water.
  • Utilizing these pure beams as targets for spectroscopic and interaction studies.

Main Results:

  • Successful production of isolated, pure beams of both para-water and ortho-water in their absolute ground states.
  • Established a method for creating samples ideal for fundamental research.
  • Demonstrated the feasibility of studying spin-conversion mechanisms and isomer-specific properties.

Conclusions:

  • Pure para- and ortho-water samples can be produced, overcoming previous separation limitations.
  • These samples provide unprecedented opportunities for precision spectroscopy and fundamental symmetry studies.
  • The research paves the way for advancements in laboratory astrophysics, astrochemistry, and hypersensitized NMR.