Q18 of 26 Page 1

(a) Write the IUPAC name of

(b) Predict all alkenes that would be formed by the dehydrohalogenation of 2-bromopentane.


(c) Arrange the following halides in the order of increasing


SN2 reactivity


CH3Cl, CH3CH2Cl, (CH3)2CHCl


(a) As, nitro group has higher priority than chlorine, so the IUPAC name will be 2,5-Dichloro-1-nitrobenzene.


(b) On dehydrohalogenation of 2-bromopentane, 2 products are possible as the H can be removed from the either side of bromine.


CH3 -CHBr-CH2-CH2-CH3 CH2=CH- CH2-CH2-CH3 + CH3 –CH=CH-CH2-CH3


As per the saytzeff’s rule the alkene with more alpha hydrogen will be more stable and hence the But-2-ene will be a major product and Butene will be a minor one.


(c) The SN2 reactions are bimolecular substitution reaction which occur in one step. As the reaction take place in one step, the steric hindreness here is the major factor. So the compound which shows least steric hindrenss will be most reactive towards the SN2 reactions. So order of reactivity will be


(CH3)2CHCl <CH3CH2Cl <CH3Cl


More from this chapter

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16

Account for the following:

(a) The highest oxidation state of a metal is exhibited in its oxides or fluorides only.


(b) Transition metals form coloured compounds.


(c) Transition elements form interstitial compounds.


 17

(a) [Ni(CO)4] possesses tetrahedral geometry while [Ni(CN)4] is square planar. Why?


(b) Write the IUPAC name of K 2[Ni(CN)4l.


(c) Write the hybridization and shape of [Fe(CN)6]3-.


 19

An organic compound (A) having molecular formula C6H6O gives a characteristic colour with aq. FeCl3 solution. When (A) is treated with CO2 and NaOH at 400 K under pressure, (B) is obtained. The compound (B) on acidification gives compound (C) which reacts with acetyl chloride to form (D) which is a popular pain killer. Write the structures of A, B, C and D.

 20

Give reasons for the following :

(a) Methyl amine in aqueous solution gives reddish brown precipitate with ferric chloride (FeCl3).


(b) Ethyl amine is a stronger base than ammonia.


(c) (CH3)3C—NH2 has a lower boiling point than CH3CH2CH2CH2 — NH2 although both are isomeric in nature.