Question

Which is the correct IUPAC name for the following structure? A. 2,3-dimethyloct-(2Z)-en-6-yne B. 6,7-dimethyloct-6-en-2-yne C. 2,3-dimethyloct-2-en-6-yne D. 6,7-dimethyloct-(6E)-en-2-yne

Answer 1

Answer:

                     Option-C (2,3-dimethyloct-2-en-6-yne) is the correct IUPAC name among the given choices.

Explanation:

Option-A i.e. 2,3-dimethyloct-(2Z)-en-6-yne is incorrect because it specifies a stereochemistry around double bond. It is not possible to assign the stereochemistry because three of the substituents around double bonds are the same. Hence, it is incorrect to assign stereo terms like Z (cis) or E (trans).

Option-B i.e. 6,7-dimethyloct-6-en-2-yne is incorrect because according to rules numbering parent chain always starts from the side having double bond at nearest position. Hence, in this name the triple bond is given first preference which is incorrect.

Option-C i.e. 2,3-dimethyloct-2-en-6-yne is correct as it has followed rules by starting numbering from double bond end and there is no stereo term used.

Option-D i.e. 6,7-dimethyloct-(6E)-en-2-yne is incorrect because it is violating both numbering rule and stereo rule.

In attached figure. the red names are the correct names for given wrong names (blue) except for option-C.