Question

The position of -Br in the compound in $C{{H}_{3}}CH=CHC\left( Br \right){{\left( C{{H}_{3}} \right)}_{2}}$ can be classified as:
A. Vinyl
B. Secondary
C. Allyl
D. Aryl

Answer 1

This question can be answered if the definition of all four terms are clear including the structure of the molecule. One option can be eliminated easily Since, aryl are the groups which are formed after the removal of Hydrogen atoms from the aromatic ring.

Complete Solution :
To clear the difference between each of the terms, we are going to look at each definition and then decide about the answer of this question.
A. Vinyl are the groups which are known as ethenyl as it formed after removing one H atom from the ethene. Its formula is $R-CH=C{{H}_{2}}$.
B. Secondary groups are those which are formed when the functional group is attached to the Carbon who is attached to two more neighbouring carbons making it a secondary functional group.
C. Allyl are the groups which are attached to a vinyl group with a bridge atom in between. Its formula is also very simple, ${{H}_{2}}C=CH-C{{H}_{2}}R$.
D. Aryl groups are formed when a Hydrogen atom is removed from the aromatic ring. But we are already seeing a straight chain here, so it is not an aryl group for sure.

$C{{H}_{3}}CH=CHC\left( Br \right){{\left( C{{H}_{3}} \right)}_{2}}$, if we look at the structure, we notice that there is presence of a vinyl group $CH=CH$, but the functional group -Br is not directly attached to the atom, rather there is a bridge of one carbon present.
So, the correct answer is “Option C”.

Note: If we look at this question, then we will find that -Br is also attached to a carbon which is bonded to other carbons making it secondary and creates a confusion between allyl and secondary, but if we notice, due to presence of vinyl group it is confirmed as allyl.