JEE MAIN - Chemistry (2018 (Offline) - No. 1)
The increasing order of basicity of the following compounds is :
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(d) < (b) < (a) < (c)
(a) < (b) < (c) < (d)
(b) < (a) < (c) < (d)
(b) < (a) < (d) < (c)
Explanation
Among all the given compounds the basic nature depends upon their tendency to donate the electron pair.
_en_1_2.png)
Because of +M effect of $$-$$NH2, lone pair will make $$\pi $$ bond and $$\pi $$ bond will go to $$-$$NH and electron density will increase at $$-$$NH.
Because of +M effect Basic nature of this will make compare to others as in other compounds there is no +M effect and +M effect has more power than other effect.
Here, in,
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$$-$$CH3 has +I effect so in N $$-$$ C bond electron will move towards nitrogen, So electron density increase at nitrogen.
And alkayl group also has +I effect, so it will also increase electron density at nitrogen.
As electron density at nitrogen increases, so tendency to donate electron pair increases and basic nature also increases.
In those following,
_en_1_4.png)
double bond has ($$-$$ I) effect, it will decrease the availability of lone pair electron at nitrogen but at (b) double bond is closer to nitrogen, so ($$-$$ I) effect will be more powerful than compound at (a), so (b) will be less basic nature.
So, the order of basicity, c > d > a > b
Because of +M effect of $$-$$NH2, lone pair will make $$\pi $$ bond and $$\pi $$ bond will go to $$-$$NH and electron density will increase at $$-$$NH.
Because of +M effect Basic nature of this will make compare to others as in other compounds there is no +M effect and +M effect has more power than other effect.
Here, in,
$$-$$CH3 has +I effect so in N $$-$$ C bond electron will move towards nitrogen, So electron density increase at nitrogen.
And alkayl group also has +I effect, so it will also increase electron density at nitrogen.
As electron density at nitrogen increases, so tendency to donate electron pair increases and basic nature also increases.
In those following,
double bond has ($$-$$ I) effect, it will decrease the availability of lone pair electron at nitrogen but at (b) double bond is closer to nitrogen, so ($$-$$ I) effect will be more powerful than compound at (a), so (b) will be less basic nature.
So, the order of basicity, c > d > a > b
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