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Arrange the following in the increasing order of their basic strengths : CH_(3)NH_(2),(CH_(3))_(2)NH,(CH_(3))_(3)N,NH_(3) |
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Answer» `NH_(3)lt(CH_(3))_(3)NltCH_(3)NH_(2)lt(CH_(3))_(2)NH` Methyl amines are stronger bases than `NH_(3)` due to the +I effect of `-CH_(3)` group. Thus greater the number of methyl GROUPS, more will be the basicity of the amine due to greater availability of ELECRON density on NITROGEN. Thus, the expected order is `NH_(3)ltCH_(3)NH_(2)lt(CH_(3))_(2)NHlt(CH_(3))_(3)N`. However, in tertiary amines, crowding of alkyl groups covers nirogen atom from al sides making the approach and bonding by `H^(+)` relatively DIFFICULT, thus the electrons are there but the PATH is blocked resulting in reduced basicity, thus the order of increasing basicity is: `NH_(3)lt(CH_(3))_(3)NltCH_(3)NH_(2)lt(CH_(3))_(2)NH`. |
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