Q24 of 50 Page 1

How would you obtain the following:

(i) Benzoquinone from phenol


(ii)2-Methylpropan-2-ol from methylmagnesium bromide


(iii)Propan-2-ol from propene


(i) Phenol can be oxidised to benzoquinone by oxidising it in the presence of Na2Cr2O7 and H2SO4 (in acidic medium).



(ii) If acetone (CH3COCH3) is treated with Grignard’s reagent of methyl magnesium bromide in the presence of ether and then hydrolysis is done, we obtain 2-methylpropan-2-ol.



(iii) Addition of water in acidic medium to propene yields propan-2-ol and not propan-1-ol. This is due to the formation of more stable intermediate 2° carbocation instead of the less stable 1° carbocation as the reaction proceeds in normal acidic condition. This is because it follows Markovnikoff’s Rule of addition.



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22

Explain the following terms giving a suitable example in each case:

(i) Ambident ligand


(ii) Denticity of a ligand


(iii) Crystal field splitting in an octahedral field


 23

Rearrange the compounds of each of the following sets in order of reactivity towards SN2 displacement:

(i) 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane


(ii) 1 -Bromo-3-methylbutane, 2-Bromo-2-methyl-butane, 2-Bromo-3-methylbutane


(iii) 1-Bromobutane, 1-Bromo-2, 2-dimethylpropane, 1- Bromo-2-methylbutane.


 25

State reasons for the following:

(i) pKb value for aniline is more than that for methylamine.


(ii) Ethylamine is soluble in water whereas aniline is not soluble in water.


(iii) Primary amines have higher boiling points than tertiary amines.


 26

Draw the structures of the monomers of the following polymers:

(i) Polythene


(ii) PVC


(iii) Teflon