Actually, you just need to know $1$ point that Mesomeric effect or M effect has a greater effect than Inductive effect or I effect. In this case, the -OH group shows +M (donating electron density) effect and the -F group shows the -I (withdrawing electron density) effect.
In compound $2$, -OH group shows the +M effect which stabilizes the positive charge.
Compound $1$ also has -OH group but due to a farther distance shows a weaker +M effect.
Compound $3$ has -F attached to it showing -I effect destabilizing the positive charge.
Actually, you just need to know $1$ point that Mesomeric effect or M effect has a greater effect than Inductive effect or I effect. In this case, the -OH group shows +M (donating electron density) effect and the -F group shows the -I (withdrawing electron density) effect.
In compound $2$, -OH group shows the +M effect which stabilizes the positive charge.
Compound $1$ also has -OH group but due to a farther distance shows a weaker +M effect.
Compound $3$ has -F attached to it showing -I effect destabilizing the positive charge.
The fact that 1) is more stable than 3) can be explained by the concept of Neighboring Group Participation (NGP)
Oxygen being more polarisable and less electronegative than fluorine tends to delocalise its lone pairs to the C⁺ atom. (Nucleophilicity of oxygen atom is more due to greater polarisability which makes oh group capable of NGP).
The fact that 1) is more stable than 3) can be explained by the concept of Neighboring Group Participation (NGP)
Oxygen being more polarisable and less electronegative than fluorine tends to delocalise its lone pairs to the C⁺ atom. (Nucleophilicity of oxygen atom is more due to greater polarisability which makes oh group capable of NGP).
Actually, you just need to know $1$ point that Mesomeric effect or M effect has a greater effect than Inductive effect or I effect. In this case, the -OH group shows +M (donating electron density) effect and the -F group shows the -I (withdrawing electron density) effect.
In compound $2$, -OH group shows the +M effect which stabilizes the positive charge.
Compound $1$ also has -OH group but due to a farther distance shows a weaker +M effect.
Compound $3$ has -F attached to it showing -I effect destabilizing the positive charge.
Therefore, final order becomes: $(2) > (1) > (3)$
Actually, you just need to know $1$ point that Mesomeric effect or M effect has a greater effect than Inductive effect or I effect. In this case, the -OH group shows +M (donating electron density) effect and the -F group shows the -I (withdrawing electron density) effect.
In compound $2$, -OH group shows the +M effect which stabilizes the positive charge.
Compound $1$ also has -OH group but due to a farther distance shows a weaker +M effect.
Compound $3$ has -F attached to it showing -I effect destabilizing the positive charge.
Therefore, final order becomes: $(2) > (1) > (3)$
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The fact that 1) is more stable than 3) can be explained by the concept of Neighboring Group Participation (NGP)
Oxygen being more polarisable and less electronegative than fluorine tends to delocalise its lone pairs to the C⁺ atom. (Nucleophilicity of oxygen atom is more due to greater polarisability which makes oh group capable of NGP).
The fact that 1) is more stable than 3) can be explained by the concept of Neighboring Group Participation (NGP)
Oxygen being more polarisable and less electronegative than fluorine tends to delocalise its lone pairs to the C⁺ atom. (Nucleophilicity of oxygen atom is more due to greater polarisability which makes oh group capable of NGP).
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