DPP-01.pdf

IIT-JEE Chemistry by N.J. Sir te:

ORGANIC chemistry 

PP - 01

Tme: 1 mnutes

ALDOL CONDENSATION: The α-hydrogen  crbony compound s cdc due to the fct tht the non so s o known s the enote non s stbzed by resonnce Θ

O CH3

O Θ

base

C

O

CH2

C

CH2 C

H

H

H

   R    I    S  .   J  .    N α- hydrogen

(enolate anion)

In queous bse, two cetdehyde moecues moec ues rect to form  β-hydroxy dehyde ced do The recton rect on s ced Ado condenston The enote on s the ntermedte n the do condenston of dehyde nd ketone Acetdehyde for nstnce, forms  dmerc product do n presence of  dute bse  ≈ 10%  Θ

OH / HOH

  → CH3 23         5°C

CH – CH2 – CHO CHO

∆

    →  → 3 – =  – 

OH

β-hydroxy butyraldehyde (Aldol)

Mechanism :

H

OH

CH2 – C – H

CH2 – C – H + H2O O

O

O

O

CH3 – C – H

+

CH2 –  C – H

Slow

H

O

O

OH

O

C – H + OH CH3– CH – CH – 2

CH3– C – CH2 – C – H + H – OH H

CH3– C – CH2 – C – H

(aldol)

O

O

 Ados re stbe stbe nd nd my my be soted They, They, however however cn be dehydrted dehydrted esy by by hetng hetng the bsc recton recton mxture or by  seprte cd ctyzed recton Thus f the bove recton rect on s heted the product s dehydrted to crotondehyde 2-buten In cd ctysed do condenston eno form of crbony s the nuceophe n pce of enote Q.1

Wrte the product nd mechnsm for gven rectons I

CH3– CH CH2 – C – H

[8]

∆       →  A     →  →  B

Dil.NaOH

O

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1

O

Dil.NaOH

II

          →  

III

  →  6 – 2 –         

Dil.NaOH

O Dil.NaOH

IV

V

∆

          → E     → F

   R    I    S  .   J  .    N Dil.NaOH ∆ C 6H 5 – C –CH 3            → G     → 

O

Q.2

Identfy the ntrmoecur do product? O

I

O

O

Dil.NaOH

  →  CH3 – C – CH2 – CH2 – CH 2 – CH 2 –C – CH 3        

O

III

∆

Dil.NaOH

  → A   → B CH3 – C – CH2 – CH2 – C – CH 3        

O

II

[7]

O

Dil.NaOH

  →  CH3 – C – CH2 – CH2 – CH2 – C – CH 3        

O

IV

Dil.NaOH  →  F           → E    ∆

O

O

V Q.3

O

Dil.NaOH

     → G CH3 – C – CH2 – CH2 – CH 2 – CH 2 – CH 2 – C – CH 3       ∆

Fnd out the tot number of do products ncudng nd excudng stereo products nd wrte the IUPA nme of products   [10] NaOH / HOH

I

  → 3 –  + 3 – 2 –           

II

  → 6 –  + 3 –           

III

5°C

NaOH / HOH 5°C

CH3

NaOH / HOH CHO + CH3 – C –CH3              →

O

5°C

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IV

CH

3

NaOH / HOH

  → CH = O + CH – CH – C – CH           3

2

3

5°C

O V

NaOH / HOH CHO + CH3 – CH2 – C – CH3              →

C 6H 5

5°C

O Q.4

Identfy the structure of substrte?

[4]

O 

Dil. NaOH

  → I A        

   R    I    S  .   J  .    N A =?

5°C

OH

OH

II

Dil. NaOH A           → CH3 (2 mole) 5°C

C –CH2 – C – CH3 A = ?

O

Q.5

CH3

ompete recton sequence :

(i) O3 (ii) Zn/H2 O



b

|| O

(i) OH (ii) ∆

 B

(i) OH A (i) C6H5CHO (iii) ∆ CH3

c

 

[7]

O ||

(i) OH A + B (ii) ∆

OH | CH – CH3

O ||

d

Θ

OH A       →

CH

3

OH

O

e

Θ ( i) OH

  → [X]       ( ii) ∆

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