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What is ortho effect ?
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What is ortho effect ?
Ortho effect refers mainly to the set of steric effects and some bonding interactions along with polar effects caused by the various substituents which are in a given molecule altering its chemical properties and physical properties. In a general sense the ortho effect is associated with substitued benzene compounds.
There are three main ortho effects in substituted benzene compounds:
- Ortho effect in substituted benzoic acid (first ortho effect) – Ortho-substituted benzoic acids are stronger acids than their meta and para isomers, regardless of the nature of the substituent
- Ortho effect in substituted aniline (second ortho effect/SIP effect)- Ortho-substituted anilines are weaker bases than their meta and para isomers, regardless of the nature of the substituent
- Ortho effect in electrophilc aromatic substitution of disubstitued benzene compounds (third ortho effect)- It refers to the set of steric effects which determines the regioselectivity of an incoming electrophile in disubstituted benzene compounds where a meta-directing group is meta to an ortho–para-directing group.
- Ortho effect in substituted benzoic acid (first ortho effect) – Ortho-substituted benzoic acids are stronger acids than their meta and para isomers, regardless of the nature of the substituent
- Ortho effect in substituted aniline (second ortho effect/SIP effect)- Ortho-substituted anilines are weaker bases than their meta and para isomers, regardless of the nature of the substituent
- Ortho effect in electrophilc aromatic substitution of disubstitued benzene compounds (third ortho effect)- It refers to the set of steric effects which determines the regioselectivity of an incoming electrophile in disubstituted benzene compounds where a meta-directing group is meta to an ortho–para-directing group.
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What is ortho effect ?
Introduction
The ortho effect is a term used in organic chemistry to describe a particular phenomenon observed in aromatic compounds. It refers to the influence of substituents on the reactivity and stability of molecules when they are positioned in the ortho position (adjacent to the aromatic ring).
Explanation
Ortho Position
The ortho position in an aromatic ring refers to the two positions on the ring directly adjacent to the substituent or functional group. These positions are numbered 1 and 2 in the IUPAC nomenclature.
Effect on Reactivity
The ortho effect typically influences the reactivity of aromatic compounds, particularly in electrophilic aromatic substitution reactions. When a substituent is positioned in the ortho position, it can either enhance or hinder the reactivity of the compound.
Enhancing Effect
In some cases, the ortho effect can enhance the reactivity of the aromatic compound. This occurs when the substituent is an electron-donating group (EDG) that can donate electrons into the aromatic ring. The presence of the EDG increases the electron density in the ortho positions, making them more nucleophilic and reactive towards electrophiles.
Hindering Effect
On the other hand, the ortho effect can also hinder the reactivity of the compound when the substituent is an electron-withdrawing group (EWG). EWGs tend to withdraw electron density from the ortho positions, making them less nucleophilic and less reactive towards electrophiles. This results in a decrease in reactivity compared to the unsubstituted compound.
Effect on Stability
In addition to reactivity, the ortho effect can also influence the stability of aromatic compounds. The presence of substituents in the ortho position can affect the resonance stabilization of the aromatic system.
Stabilizing Effect
If the substituent is an EDG, it can stabilize the aromatic system by donating electron density into the ring. This increased electron density improves the resonance stabilization, leading to a more stable compound.
Destabilizing Effect
Conversely, if the substituent is an EWG, it can destabilize the aromatic system by withdrawing electron density from the ring. This decreases the resonance stabilization and results in a less stable compound compared to the unsubstituted aromatic compound.
Conclusion
In summary, the ortho effect refers to the influence of substituents in the ortho position of an aromatic compound. It can affect the reactivity and stability of the compound, with electron-donating groups enhancing reactivity and stability, while electron-withdrawing groups hindering reactivity and stability. Understanding the ortho effect is important in predicting and explaining the behavior of aromatic compounds in various reactions.
The ortho effect is a term used in organic chemistry to describe a particular phenomenon observed in aromatic compounds. It refers to the influence of substituents on the reactivity and stability of molecules when they are positioned in the ortho position (adjacent to the aromatic ring).
Explanation
Ortho Position
The ortho position in an aromatic ring refers to the two positions on the ring directly adjacent to the substituent or functional group. These positions are numbered 1 and 2 in the IUPAC nomenclature.
Effect on Reactivity
The ortho effect typically influences the reactivity of aromatic compounds, particularly in electrophilic aromatic substitution reactions. When a substituent is positioned in the ortho position, it can either enhance or hinder the reactivity of the compound.
Enhancing Effect
In some cases, the ortho effect can enhance the reactivity of the aromatic compound. This occurs when the substituent is an electron-donating group (EDG) that can donate electrons into the aromatic ring. The presence of the EDG increases the electron density in the ortho positions, making them more nucleophilic and reactive towards electrophiles.
Hindering Effect
On the other hand, the ortho effect can also hinder the reactivity of the compound when the substituent is an electron-withdrawing group (EWG). EWGs tend to withdraw electron density from the ortho positions, making them less nucleophilic and less reactive towards electrophiles. This results in a decrease in reactivity compared to the unsubstituted compound.
Effect on Stability
In addition to reactivity, the ortho effect can also influence the stability of aromatic compounds. The presence of substituents in the ortho position can affect the resonance stabilization of the aromatic system.
Stabilizing Effect
If the substituent is an EDG, it can stabilize the aromatic system by donating electron density into the ring. This increased electron density improves the resonance stabilization, leading to a more stable compound.
Destabilizing Effect
Conversely, if the substituent is an EWG, it can destabilize the aromatic system by withdrawing electron density from the ring. This decreases the resonance stabilization and results in a less stable compound compared to the unsubstituted aromatic compound.
Conclusion
In summary, the ortho effect refers to the influence of substituents in the ortho position of an aromatic compound. It can affect the reactivity and stability of the compound, with electron-donating groups enhancing reactivity and stability, while electron-withdrawing groups hindering reactivity and stability. Understanding the ortho effect is important in predicting and explaining the behavior of aromatic compounds in various reactions.
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What is ortho effect ? for IIT JAM 2025 is part of IIT JAM preparation. The Question and answers have been prepared according to the IIT JAM exam syllabus. Information about What is ortho effect ? covers all topics & solutions for IIT JAM 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for What is ortho effect ?.
What is ortho effect ? for IIT JAM 2025 is part of IIT JAM preparation. The Question and answers have been prepared according to the IIT JAM exam syllabus. Information about What is ortho effect ? covers all topics & solutions for IIT JAM 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for What is ortho effect ?.
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