Organic Chemistry Some Basic Principles and Techniques Test - 28

Polar compounds will have more interaction with silica gel and hence polar compounds won't move much in the stationery phase.
Non polar compounds will have lesser interaction with the silica or the stationery phase and will move higher than the polar compound.

$$-NO_2$$ is the strongest -I group among all the neutral group because of the presence of + charge on N atom as shown in structure

$$-Cl$$ is a more electro negative group and when attached with a phenyl group (refer to image ) it would acts as electron withdraing group and act as (O-P) directions. {Ortho para}

$$CH_2=CH-$$ and phenyl both contain double bonds, Since we know -NO, C=C both can show +M and -M effect both hence all of the above options are correct.

As %s character increases, electronegativity of orbitals increases which means its tendency to pull electron towards itself also increases hence -I effect increases

(-) charge is a stronger donor than lone pairs hence the strongest +M effect is shown by $$-O^-$$.

Correct Answer: Option C

Explanation:

• In an organic molecule, the $$-I$$ effect describes the tendency of a certain group to attract the shared pair of electrons towards itself.
• The charges thus created are permanent charges and are, therefore, partial.
• This effect becomes negligible after three carbon atoms.

 

1. $$CN$$ $$\&$$ $$NC$$
Nitrogen is more electronegative than carbon. Therefore, it has more tendency to attract shared pair of electrons towards itself.
$$-I$$ effect order is $$CN < NC$$

2. $$F$$ $$\&$$ $$CF_{3}$$
Due to the presence of three $$Fluorine$$ on $$CF_{3}$$, it becomes a very strong group of reverse hyperconjugation. Thus, it has a greater tendency to attract a shared electron cloud towards itself than a single $$Fluorine$$ atom.
$$-I$$ effect order is $$F < CF_{3}$$

3. $$OH^{+}_{2}$$ $$\&$$ $$OH_{2}$$
Both of the given species have similar structures and atoms except for a positive charge on $${OH_{2}}^+$$. Due to this positive charge, it has more tendency to attract shared pair of electrons towards itself.
$$-I$$ effect order is $$OH^{+}_{2} > OH_{2}$$

4. $$NO_{2}$$ $$\&$$ $$NH^{+}_{3}$$
Due to the positive charge on $$NH^{+}_{3}$$ has more tendency to attract shared pair of electrons towards itself.
$$-I$$ effect order is $$NO_{2} < NH^{+}_{3}$$

Hence, option $$C$$ is the correct answer.

correct order is $$ii>i>iii $$

Since + charge is more electronegative than neutral atom therefore correct order is
$$-OH_2^+$$>$$-NH_3^+$$>$$-NO_2$$>$$-F$$. Hence least -I effect is shown by -F

To show inductive effect compound must contain electronegative element/ eletropositive element attatched to C-atom. So that movement of electrons away from chain/towards chain  would occur. This is possible only in case of Butanal among given options.