-2
$\begingroup$

enter image description here

Find the IUPAC name of the above structure.

This question was asked in my Chemistry exam. I could not figure out whether it is a ketone or an ester. My attempts:

1.If i consider the whole compound as an ester then part to the left of C-O-C is the acid part and the part to the right is the alcohol part. Thus the IUPAC name is:

Ethyl 4,5-dibromoheptan-2-one-6-oate

2.If the consider the part to the left of C-O-C as ketone and the part to the right as ester then IUPAC name comes out to be:

4,5-dibromopentan-2-one Ethyl Methanoate

Is any of my attempts correct and if not then why not?

Improve this question
$\endgroup$
6
  • 4
    $\begingroup$ Ester group is more important but your first name is still quite thoroughly wrong. $\endgroup$
    – Mithoron
    Commented Jan 5, 2017 at 18:06
  • $\begingroup$ What about the second one? $\endgroup$
    – MrAP
    Commented Jan 5, 2017 at 18:07
  • 1
    $\begingroup$ Related: Nomenclature priorities with ethers, acyl groups and ketones $\endgroup$
    – user7951
    Commented Jan 5, 2017 at 18:12
  • $\begingroup$ Second is two molecules, you'd get if you'd manage to cleave it reductivly. $\endgroup$
    – Mithoron
    Commented Jan 5, 2017 at 18:15
  • $\begingroup$ What is the IUPAC name then and why has this question been downvoted? $\endgroup$
    – MrAP
    Commented Jan 5, 2017 at 18:59

1 Answer 1

Reset to default
4
$\begingroup$

According to Section P-41 in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the order of seniority of classes in decreasing order of seniority is as follows.

(…)
9. esters
(…)
16. ketones
(…)

Therefore, the compound that is given in the question is named as an ester.

The names of esters are usually formed by placing the alcoholic component in front of the name of the acid component as a separate word.

P-65.6.1 General methodology

Neutral salts and esters are both named using the name of the anion derived from the name of the acid. Anion names are formed by changing an ‘-ic acid’ ending of an acid name to ‘-ate’ and an ‘-ous acid’ ending of an acid name to ‘-ite’. Then, salts are named using the names of cations, and esters the names of organyl groups, cited as separate words in front of the name of the anion.

Therefore, the name of the parent structure without further substituents is ethyl hexanoate.

This ester is substituted using the usual principles of substitutive nomenclature. A low locant is assigned first to the principal characteristic group (i.e. the ester group). The prefix ‘oxo’, denoting $\ce{=O}$, is used to indicate a carbonyl group when the group cannot be cited as suffix.

Thus, the complete name for the compound that is given in the question is ethyl 2,3-dibromo-5-oxohexanoate.

ethyl 2,3-dibromo-5-oxohexanoate

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.