More specifically, see the image down below:

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Would it be pentan-2-ene-3-yl propanoate? Do you just add the 2-ene to specify the position of the double bond?

  • $\begingroup$ Prefix the name with (Z). $\endgroup$
    – user55119
    Jan 21 at 19:59

1 Answer 1


According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the names of esters are generally formed by placing the alcoholic component in front of the name of the acid component as a separate word (e.g. ethyl acetate).

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.

The organyl group is named using the using the usual methodology.


The presence of free valences formally derived from the loss of one or more hydrogen atoms from a parent hydride is denoted by suffixes ‘yl’, ‘ylidene’, and ‘ylidyne’, together with multiplying prefixes indicating the number of free valences; lowest locants are assigned to all free valences as a set, then in the order ‘yl’, ‘ylidene’, ‘ylidyne’. In names, the suffixes are cited in the order ‘yl’, ‘ylidene’, ‘ylidyne’. The suffixes ‘ylidene’ and ‘ylidyne’ are used only to indicate the attachment of a substituent to a parent hydride or parent substituent by a double or triple bond, respectively.


Systematic names are formed by using the suffixes ‘yl’, ‘ylidene’ and ‘ylidyne’, with elision of the final letter ‘e’ of parent hydrides, when present, according to two methods:

  1. The suffixes ‘yl’, ‘ylidene’, and ‘ylidyne’ replace the ending ‘ane’ of the parent hydride name. The atom with the free valence terminates a chain and always has the locant ‘1’, which is omitted from the name. This method is recommended primarily for saturated acyclic and monocyclic hydrocarbon substituent groups and for the mononuclear hydrides of silicon, germanium, tin, and lead. Substituent groups formed by this method are referred to as ‘alkyl-type substituent groups’;
  2. The suffixes ‘yl’, ‘ylidene’, and ‘ylidyne’ are added to the name of the parent hydride with elision of the terminal letter ‘e’, if present, when followed immediately by the letter ‘y’. The locants for the atoms of free valences are as low as is consistent with any established numbering of the parent hydride and, except for mononuclear parent hydrides or the suffix ‘ylidyne’, the locant ‘1’ must be cited. This method is used to generate names of ‘alkanyl-type substituent groups’ that are simple substituent groups with free valences at positions other than ‘1’.


In this case, Method (2) is used because the free valence is not at position ‘1’. The name of the parent hydride (2E)-pent-2-ene is changed to the alkanyl-type substituent group pentenyl by addition of the suffix ‘yl’ and elision of the terminal letter ‘e’. A low locant is given first to the free valence, which gives penten-3-yl. After adding the other locants we finally get the complete name (2Z)-pent-2-en-3-yl propanoate.

(2Z)-pent-2-en-3-yl propanoate

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