Monday, 20 January 2020

Application of Inductive Effect

Tricky chemistry basics by suman negi January 20, 2020 GENERAL ORGANIC CHEMISTRY (GOC) , 1 Comments

Application of Inductive Effect

[A] Stability of Intermediate(मध्यवर्ती का स्थायित्व)--

●Stability of Carbocation(कार्बोकैटायन का स्थायित्व ------
1-contain positive charge धन आवेश
2-incomplete Octet ( less than 8 electron ) अपूर्ण अष्टक
3- electron poor species (इलेक्ट्रान ऋणी)

☆ Effect of + I group---

+I group are electron donating group.So they increase the electron density at electron poor centre( carbocation ) by donating them electron pairs. Hence they make Carbocation Centre electron rich that means the carbocation become stable .
+I समूह इलेक्ट्रॉन दाता समूह होते हैं । अतः वे इलेक्ट्रॉन ऋणी केंद्र ( कार्बो धनायन ) को इलेक्ट्रॉन दान करते हैं ।इलेक्ट्रॉन दान करने के पश्चात कार्बोधनायन केन्द्र ( इलेक्ट्रॉन गरीब केंद्र ) धनी हो जाता है । जिसके कारण कार्बोकैटायन का स्थायित्व बढ़ जाता है

☆ Effect of - I group---

-I group are electron Attracting group.So they decrease the electron density at electron poor centre( carbocation ) by attracting them electron pairs. Hence they make Carbocation Centre electron rich that means the carbocation become stable .
-I समूह इलेक्ट्रॉन ग्राही समूह होते हैं । अतः वे इलेक्ट्रॉन ऋणी केंद्र ( कार्बो धनायन ) से इलेक्ट्रॉन ग्रहण करते हैं ।इलेक्ट्रॉन ग्रहण करने के पश्चात कार्बोधनायन केन्द्र ( इलेक्ट्रॉन गरीब केंद्र ) धनी हो जाता है । जिसके कारण कार्बोकैटायन का स्थायित्व घट जाता है ।

●Stability of Free Radical (मुक्त मूलकों का स्थायित्व ------
1-contain Unpaired electron ( अयुग्मित इलेक्ट्रान )
2-incomplete Octet ( 7 electron ) अपूर्ण अष्टक
3- electron poor species (इलेक्ट्रान ऋणी)

☆ Effect of + I group---

+I group are electron donating group.So they increase the electron density at electron poor centre( Free Radical centre) by donating them electron pairs. Hence they make Free Radical Centre electron rich that means the Free Radical become stable.
+I समूह इलेक्ट्रॉन ग्राही समूह होते हैं । अतः वे इलेक्ट्रॉन ऋणी केंद्र ( मुक्त मूलक ) से इलेक्ट्रॉन ग्रहण करते हैं ।इलेक्ट्रॉन ग्रहण करने के पश्चात मुक्त मूलक केन्द्र ( इलेक्ट्रॉन गरीब केंद्र ) धनी हो जाता है । जिसके कारण कार्बोकैटायन का स्थायित्व बढ़ जाता है ।

☆ Effect of - I group---

-I group are electron Attracting group.So they decrease the electron density at electron poor centre( Free Radical ) by attracting them electron pairs. Hence they make Free Radical Centre electron poor that means the Free Radical become less stable .
-I समूह इलेक्ट्रॉन ग्राही समूह होते हैं । अतः वे इलेक्ट्रॉन ऋणी केंद्र ( मुक्त मूलक ) से इलेक्ट्रॉन ग्रहण करते हैं ।इलेक्ट्रॉन ग्रहण करने के पश्चात मुक्त मूलक केन्द्र (इलेक्ट्रॉन गरीब केंद्र )धनी हो जाता है । जिसके कारण मुक्त मूलकों का स्थायित्व घट जाता है ।

कार्बोएनायन का स्थायित्व ------
1-contain Negative charge ऋण आवेश
2-complete Octet ( 8 electron )पूर्ण अष्टक
3- electron Rich species (इलेक्ट्रान धनी )

☆ Effect of + I group---

+I group are electron donating group.So they increase the electron density at electron Rich centre( carbanion ) by donating them electron pairs. Due to accumulation of excess charge at electron rich centre (carbanion ) , more more repulsion occurs . Fue to more repulsion Carboanion centre become unstable , that is stability decreases .

Trick--

☆ Effect of - I group---
+I group are electron attracting group.So they decrease the electron density at electron Rich centre( carbanion ) by attracting electron pairs from them . Due to removal of excess of charge at electron rich centre (carbanion ) , Less repulsion occurs . Due to less repulsion Carboanion centre become stable , that is stability increases .

Trick--

[ B ] Reactivity----

Order of nucleophilic attack at carbonyl carbon ---
nucleophile ( nucleus loving ) is a negative charged species . So nucleophile is a electron rich species and they want to attack at electron poor centre that means nucleophile attack at that carbon where more positive charge accumulate .

Trick--
● More the number of + I group (electron donating group ) more the the electron density at carbonyl carbon , lesser the nucleophilic attack .
● More the number of - I group lesser the electron density at carbonyl carbon , more the nucleophilic attack .

Reactivity of alkyl halide in SN¹
reaction ---

In SN¹ reaction intermediate formed is Carbocation that means more the stability of Carbocation , quickly the SN1 reaction takes place Hence more the degree of carbon on alkyl halide , stability of intermediate Carbo cation increses due to which the reactivity of alkyl halide also increases .

Reactivity of alkyl halide in SN²
reaction ---

In SN² reaction nucleophile attack initially in rate determining step . so here we focus on nucleophilic attack . as we know before , nuclear attack occurs at that carbon of alkyl halide which contain more positive charge ( which is more electron deficient ) . Hence less the degree of carbon on alkyl halide ,lesser the electron density . Due to which the reactivity of alkyl halide also increases .

strength of carboxylic acid---

are those which release H+ Ion quickly and form a conjugate base ( anion ) .If acid is less stable than it will easily lose H+ ion and converted into stable conjugate base that means stability of conjugate base depend on acid structure.