I found this question in the Resonance DLPD Organic Chemistry book on Page 55:

What is the hybridization of carbon atoms present in the smallest ester?

The smallest ester as far as I know is methyl formate ($\ce{HCOOCH3}$):

methyl formate

The first carbon atom (on left) has 3 σ bonds and the one on the right has 4 σ bonds. Hence, the hybridization is $\mathrm{sp}^2$ and $\mathrm{sp}^3$, respectively.

However, according to the answer given in the book, all carbon atoms in the smallest ester are $\mathrm{sp}^2$ hybridized.

What did I do wrong? Is there a smaller ester? Or the hybridization of the one I have above not correctly determined?

  • $\begingroup$ Consider the hybrid obtained after resonance: This is only a canonical structure $\endgroup$ Commented Feb 9, 2019 at 13:28
  • $\begingroup$ @YUSUFHASAN sorry I don't know about resonance as I am only a high school student and have only recently started studying organic chemistry. $\endgroup$
    – user69284
    Commented Feb 9, 2019 at 13:31
  • 1
    $\begingroup$ Ok...See this could be either one of two cases: the book wanted you to consider only this structure,and so there is a misprint, as then the answer would be one sp2 and one sp3 carbon. Or, they wanted you to consider resonance, and understand the fact that the hybridization will be somewhere between sp2 and sp3(atleast I would have done that), but the answer doesn't show that.So,most probably,it is a misprint.Although, resonance should be taken into consideration as the actual existence is of the hybrid Check it out here $\endgroup$ Commented Feb 9, 2019 at 13:37

1 Answer 1


You are right. Methyl formate has one $\mathrm{sp}^2$ and one $\mathrm{sp}^3$ hybridized orbital.

Your book probably has a misprint.

  • 1
    $\begingroup$ @YUSUFHASAN Atoms are not hybridized, orbitals are. Please avoid misleading edits with questionable improvements. Also, orbitals are denoted with upright roman letters. $\endgroup$
    – andselisk
    Commented Feb 9, 2019 at 19:37

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