Question

Identify the correct statements about the nomenclature of alkylidene dihalides:
(A) Dihalogenalkanes in which two halogen atoms of the same type are present on the same carbon atom are called alkylidene dihalides.
(B) In common naming these are called alkylene dihalides.
(C] In the IUPAC system, the locants for the two halogen atoms are prefixed to the name of dihaloalkane.
(D) Both [A] and [C]

Answer 1

Hint: An alkylidene dihalide is also known as a gem dihalide. It is obtained from an alkane where two hydrogen atoms are replaced from the same carbon atoms. You can use this to answer the given question.

Complete step by step solution:
To answer this, firstly we have to discuss what alkylidene dihalides are.
We also know alkylidene dihalides by the name gem dihalide which is basically an abbreviation for geminal dihalides.
The term ‘geminal’ denotes that the substituent atom or group is attached to the same atom in a molecule.
An alkylidene group is a class of a divalent functional group. It is derived from an alkane by removing two hydrogen atoms from the same carbon atom.
In an alkylidene dihalide, the hydrogen atom removed from the same carbon atom is replaced by two similar halogen groups. For example, $C{{H}_{3}}CH{{X}_{2}}$, where X stands for any halogen.
Now, let us go through the options and identify the correct one.
We can understand from the above discussion that the first option is correct.
In the second option, the name alkylene dihalides are used for vicinal dihalides and not geminal dihalides. So, this option is incorrect.
And lastly, the third option is also correct as in IUPAC naming we use the prefix dihaloalkane for them. A dihalogen derivative of an alkane is known as dihaloalkane.

Therefore, the correct answer is option (D) Both (A) and (C).

Note: We often use the term geminal and vicinal in chemistry. We use geminal for the same carbon atom and vicinal means adjacent carbon atoms. In geminal dihalides, the di-halide group is present on the same carbon atom as we have already discussed above whereas, in vicinal dihalides, the halide groups are attached on adjacent carbon atoms.