Phenol

Organic chemistry

1. PHENOL By Rashmi Mishra

2. INTRODUCTION Compound with the general formula   ArOH (Phenyl, substituted phenyl or some other aryl group)

3. CHEMICAL REACTIONS OF PHENOL Acidity salt formation Ester formation Ring substitution reactions Nitration Halogenation Sulfonation Friedal craft alkylation Friedal craft acylation Nitrosation Coupling with diazonium salt Carbonation Reimer- Tiemann reaction Williamson synthesis

4. Acidity salt formation COOH > Phenol > H 2 O (Ka of COOH = 10 -5 ) (Ka of Phenol 10 -10 ) COOH > Phenol > Alcohol (Ka of Alcohol = 10 -16 to 10 -18 )

5. Why OH attached to Aromatic ring is more acidic than OH attached to R??????

6. Additional structures as oxygen is basic ------ can share more than a pair of electron with ring.

7. EFFECT OF SUBSTITUENT ON ACIDITY OF PHENOL Nature of substituent: Electron withdrawing substituent (-NO 2 , -CN, -X): Withdraws electron Disperse – ve charge Stabilizes compound Increase acidity Electron releasing substituent (-OH, -R): Releases electron Destabilize phenoxide ion Increse – ve charge Decreaes acidity of phenol Position of substituent: Electron withdrawing and electron releasing group more pronounce at ortho and para (Due to resonance)

8. Why para nitro phenol > acidic than ortho nitro phenol ??????

9. 2. Ester formation

10. Ring Substitution Nitration

11. Ring Substitution b. Halogenation

12. Ring Substitution c. Sulfonation

13. d. Friedel Craft Alkylation (Preparation of alkylphenols )

14. e. Friedel Craft Acylation (Fries rearrangement)

15. f. Nitrosation

16. g. Coupling with diazonium salt

17. Carbonation (Kolbe reaction / Synthesis of phenolic acids) Salt of phenol reacts with CO 2 --------- brings about substitution of carboxylic group –COOH for hydrogen of ring = Kolbe reaction.

18. i . Reimer – Tiemann reaction ( Aldehyde formation / Synthesis of phenolic aldehydes ) Treatment of phenol with chloroform and aq. Hydroxide …….. Provide aldehyde group onto ring (at ortho to OH ) = Reimer- Tiemann reaction.

19. Williamson synthesis (Ether formation): Nucleophilic substitution reaction