CBSE Class 12 Chemistry Organic Chemistry Questions

9. In case of optically active alkyl halide, SN2 mechanism results in the inversion of configuration while SN1 mechanism in racemisation.

10. Aryl halides are much less reactive towards nucleopillic substitution reactions. Presence of electron withdrawing groups (like –NO2 , –CN, –COOH etc.) at o– and/or p-position to halogen increases the rate of reaction.

12. All the three types of monohydric alcohols (1°, 2° or 3°) except methanol can be prepared from Grignard Reagent

13. Alcohols

14. Presence of electron withdrawing group increases the acid strength of alcohol, phenol and carboxylic acid while presence of electron donating group decreases the acid strength. E.W.G. : NO2, –X, –CN, –COOH, etc., E.D.G. : –R, –OR, –OH, –NH2 etc.

15. In electrophilic aromatic substitution reaction, ring activating groups like –OH, –NH2, –OR, are o– and p– directing whereas ring deactivating groups like –CHO, > C = 0, –COOH, –NO2, –SO3H are m-directing. Halogens (F, Cl, Br and I) are deactivating but are o– and p– directing groups.

16. 3° alcohols are resistant to oxidation due to lack of -hydrogen.

17. Order of Acid strength : Alcohol < Phenol < Carboxylic acid, it is because of resonance stabilization of phenoxide and carboxylate ion. In carboxylate ion negative charge is delocalised over two oxygen atoms. while in phenoxide ion it is delocalised over one oxygen atom and the less electronegative C atom of benzene ring.

18. All organic compounds which form intermolecular H-bonds with water are soluble in water.

19. Intermolecular H-bonds of p- and m- nitrophenol increases water solubility/ Acid strength while intramolecular H-bonds in o-nitrophenol decreases

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