Question

What is wrong with the following names? Give the correct name for each compound. a. 2-ethylpropane b. 5-iodo- 5,6-dimethylhexane c. cis-4-methyl-3-pentene d. 2-bromo-3-butanol

Short answer

The correct names of each compound are

(a)2-methyl -butane

(b) 3-iodo-3-methyl-heptane

(c)2-methyl-2-pentene

(d) 3-bromo-2-butanol

Step-by-step solution

Correct name regarding part (a)

Abiding by the IUPAC rule with the longest possible carbon atom chain, we determine the root name, after observing the molecular structure of the given compound "2-ethyl-propane" it can be noticed that the longest possible carbon chain would consist of four carbon atoms which tells us the root name shall be "but".

Now there would be just one methyl group attached to the second carbon atom.

Therefore,the correct name would be "2-methyl-butane"

Correct name regarding part (b)

Abiding by the IUPAC rule with the longest possible carbon atom chain we determine the root name, after observing the molecular structure of the given compound,

“5-iodo-5,6-dimethyl-hexane".It can be noticed that the longest possible carbon chain would consist of seven carbon atoms which tells us the root name shall be "hept".

Now there would be just one methyl and one iodine group attached to the third carbon atom (the biggest branching).Therefore, the correct name would be "3-iodo-3-methyl-heptane"

Correct name regarding part (c)

Abiding by the IUPAC rule with the largest carbon bond branching we determine where we shall start counting carbon atoms, after observing the molecular structure of the given compound, "cis-1-methyl-3-pentane", it can be noticed that the largest carbon bond branching would be at the fourth carbon alom which tells us that, the counting should start close to that carbon, "from the right side of the diagram". Now there would be just one methyl group attached to the second carbon atom (the biggest branching). which tells us that the given compound doesn't have enough functional groups to be a "cis" isomerTherefore the correct name would be "2-methyl-2-pentene"

Correct name regarding part (d)

Abiding by the IUPAC rule with the largest carbon bond branching or by main functional group we determine where we shall start counting carbon atoms, after observing the molecular structure of the given compound, "2-bromo-3-butanol", we can notice that the main functional group would be "OH" which tells us that the counting should start close to that group, "from the right side of the diagram". Now there would be one bromine group attached to the third carbon atom. Therefore, the correct name would be "3-bromo-2-butanol"