It is blurry, but it looks like: (C2H5)2CHCH(CH3)CH(CH3)2, which would be 4-ethyl-2,3-dimethylhexane.

The displayed formula the OP drew is simply wrong - what with it having two carbon atoms with only three bonds.

Reply 12

charco

Study Forum Helper

18

Original post by Pigster

It is blurry, but it looks like: (C2H5)2CHCH(CH3)CH(CH3)2, which would be 4-ethyl-2,3-dimethylhexane.

The displayed formula the OP drew is simply wrong - what with it having two carbon atoms with only three bonds.

Yes, it's missing hydrogen atoms but it looks to me like (C₂H₅)₂CHCH₂CH(CH₃)CH(CH₃)₂
... when you add the hydrogen atoms in, making it 5-ethyl-2,3-dimethylheptane

Reply 13

Pigster

20

Original post by charco

Yes, it's missing hydrogen atoms but it looks to me like (C₂H₅)₂CHCH₂CH(CH₃)CH(CH₃)₂
... when you add the hydrogen atoms in, making it 5-ethyl-2,3-dimethylheptane

I have to disagree on two counts: 1. the OP's displayed does not match the structural given in the Q and hence overall the answer is wrong.
2. if we're only interested in ensuring the OP has named what they drew, rather than what they should have drawn, then the point of first difference rule surely would say 3,5,6 rather than 5,2,3?

Original post by Pigster

I have to disagree on two counts: 1. the OP's displayed does not match the structural given in the Q and hence overall the answer is wrong.
2. if we're only interested in ensuring the OP has named what they drew, rather than what they should have drawn, then the point of first difference rule surely would say 3,5,6 rather than 5,2,3?

I was only answering the (partial) structure that the OP drew.
However, you raise an interesting point. I was always lead to believe that the end was chosen to give the lowest numerical locants. You have raised "the point of first difference rule". I am not familiar with this rule.
OK I've found the documentation:
"Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When compairing a series of numbers, the series that is the "lowest" is the one which contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name."
From IUPAC http://www.chem.uiuc.edu/GenChemReferences/nomenclature_rules.html
Indeed sir, you are correct.

(edited 3 years ago)

Reply 15

Pigster

20

Original post by charco

I was only answering the (partial) structure that the OP drew.
However, you raise an interesting point. I was always lead to believe that the end was chosen to give the lowest numerical locants. You have raised "the point of first difference rule". I am not familiar with this rule. Do you have a reference?