Question

The IUPAC name of the compound $Br(Cl)IC - C{F_3}$ is:
A.2-bromo-2-chloro-2-iodo-1,1,1-trifluoroethane
B.1,1,1-trifluoro-2-bromo-2-chloro-2-iodoethane
C.2-bromo-2-chloro-1,1,1-trifluoro-2-iodoethane
D.1-bromo-1-chloro-2,2,2-trifluoro-1-iodo ethane

Answer 1

Hint: To write IUPAC names of any compound, we need some rules to be followed.
Here, we have 2 carbon, with Bromo, Chloro, fluoro and Iodo halogens. No other functional group is present. So, let us discuss the numbering of carbon chains and the correct naming of compounds according to IUPAC rules.

Complete step by step answer:
The general way of writing IUPAC nomenclature, can be summarized as:
Secondary prefix + primary prefix + word root + primary suffix + secondary prefix.
Now, let us discuss each one in reference to the above question.
For secondary prefix:
Firstly, we identify the parent chain in the compound. Here we have 2 carbon chains.
Numbering of this carbon chain is done from the place, halogen appears first, but here from both sides, halogen appears at number 1 carbon, so in case of conflict, give a lower number to carbon which has alphabetically lower value. Here, Bromo, Chloro, fluoro and Iodo are present. So we give a lower number to Bromo, as ‘B’ appears first in alphabetical order.
Now, we can also see that fluorine appears 3 times, so we use the word, di, tri, tetra for repetition of such substituents.
Also arrange them in alphabetical order for writing secondary prefixes.
So the secondary prefix is 1-bromo-1-chloro-2,2,2-trifluoro-1-iodo
Now, primary prefix is not considered here, as it has words like cyclo, bicyclo, spiro. But here no such structure is involved.
Now the word root is based on the number of carbons. Here 2 carbons are present, so the word root will become ‘eth-’.
Now the primary suffix depends on the carbon chain to be alkane, alkene or alkyne.
For alkane it will end in ‘-ane’, for alkene it will be ‘-ene’ and for alkyne it will be ‘-yne’.
Here, in a given compound we don’t have a double or triple bond, so it is simple alkane thus the primary suffix will be ‘-ane’.
Now, secondary prefix comes when there is presence of functional groups. But here we don’t have any functional groups.
Thus, summarizing, we see correct option is (D) 1-bromo-1-chloro-2,2,2-trifluoro-1-iodo ethane.


Note:
We should be careful in selecting the parent chain, numbering from which end, and also for selecting the primary functional groups if multiple functional groups are present.
Remember to repeat the number as many times as substituents are appearing, like here we used number 2, three times as fluorine is appearing 3 times. Also be careful to use word di, tri, tetra depending on the number of times the same functional group or substituent is coming, like here trifluoro is used.
The most common mistake that one may do is considering di, tri, tetra word for writing names, which has to be avoided, only the substituent mane has to be considered, not the repeating times, like di, tri, tetra.