Question

Where is dative bond not involved?
This question has multiple correct options
(A) Protonation of ether
(B) Dissolution of HF in water
(C) Dimerisation of benzoic acid
(D) Formation of $B{{e}_{2}}C{{l}_{4}}$

Answer 1

Hint: Attempt this question by understanding about the dative bonds and then check each statement whether the dative bond is involved or not. Basically they are the covalent bonds (a bond which is formed by a shared pair of electrons) in which electrons are contributed by the same atom. It is also known as coordinate bond.

Complete answer:
Let us begin with the discussion of dative bonds:-
-Dative bond (also known as coordinate bond) is generally formed when one atom has at least one lone pair of electrons and another atom has an empty orbital to share those electrons.
-Since it is also a type of covalent bond so it must share a pair of electrons to form the bond but here the whole contribution towards sharing is done by one atom and other accept it to complete its octet in order to achieve a stable state. This bond is represented by an arrow whose tail represents the side of the donor atom and the arrowhead represents the side of the acceptor atom.
Now let us check whether the following statements have any involvement of dative bond or not:-
(A) Protonation of ether: When we protonate a molecule of ether in the presence of acidic medic , then at a certain time the O atom of ether donates its electron to the H atom of water and then detaches in the further series of reactions. Therefore we can say that dative bond is involved in this reaction.
(B) Dissolution of HF in water: As we know that H and F atoms have high electronegativity differences due to which hydrogen – fluoride covalent bond is highly polarized. When HF is dissolved in water, the ${{H}_{2}}O$ molecules get oriented around the HF molecule through hydrogen bonding and stabilize it. Thus, we can say that no dative bond is involved in this case.
(C) Dimerisation of benzoic acid: Hydrogen bond is involved in the dimerisation of benzoic acid because the H atom of one acid molecule interacts with the O atom of the neighboring acid molecule through hydrogen bonding. Hence there is no dative bond involved in this case as well.
(D) Formation of $B{{e}_{2}}C{{l}_{4}}$: $B{{e}_{2}}C{{l}_{4}}$ is formed by the dimerisation of $BeC{{l}_{2}}$ where Cl atom of a molecule completely donates its lone pair to Be atom of another molecule which means the bond formed during the formation of $B{{e}_{2}}C{{l}_{4}}$ is a dative bond. Hence this case involves dative bonds.

-From the above data, we may conclude that the correct options are as follows:-
(B) Dissolution of HF in water
(C) Dimerisation of benzoic acid

Note:
Remember that dative bonds are commonly seen in reactions which involve hydrogen atoms.
-The hydrogen bond involved in case of dissolution of HF not only stabilizes the HF molecular dipole, but it also weakens the hydrogen – fluoride covalent bond as a result of which, the H—F bond stretches and then fully breaks.