{"id":1587,"date":"2018-03-21T15:28:33","date_gmt":"2018-03-21T15:28:33","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/chapter\/esters-structures-and-names\/"},"modified":"2018-11-08T16:46:23","modified_gmt":"2018-11-08T16:46:23","slug":"esters-structures-and-names","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/esters-structures-and-names\/","title":{"raw":"15.6 Esters: Structures and Names","rendered":"15.6 Esters: Structures and Names"},"content":{"raw":"
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Learning Objectives<\/h3>\r\n
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  1. Identify the general structure for an ester.<\/li>\r\n \t
  2. Use common names to name esters.<\/li>\r\n \t
  3. Name esters according to the IUPAC system.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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    Esters have the general formula RCOOR\u2032, where R may be a hydrogen atom, an alkyl group, or an aryl group, and R\u2032 may be an alkyl group or an aryl group but not<\/em> a hydrogen atom. (If it were hydrogen atom, the compound would be a carboxylic acid.) Figure 15.4 \"The Structure of Esters\"<\/a> shows models for two common esters.<\/p>\r\n\r\n

    \r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1545\"]\"image\" Figure 15.4 The Structure of Esters.\u00a0Esters feature a carbon-to-oxygen double bond in which the carbon is also singly bonded to a second oxygen atom, which is then joined to an alkyl or an aryl group. The esters shown here are ethyl acetate (a) and methyl butyrate (b).\u00a0 (Note color scheme:\u00a0 Green = H, blue = C, red = O)[\/caption]\r\n\r\n<\/div>\r\n

    Esters occur widely in nature. Unlike carboxylic acids, esters generally have pleasant odors and are often responsible for the characteristic fragrances of fruits and flowers. Once a flower or fruit has been chemically analyzed, flavor chemists can attempt to duplicate the natural odor or taste. Both natural and synthetic esters are used in perfumes and as flavoring agents.<\/p>\r\n\r\n

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    Note<\/h3>\r\n

    Fats and vegetable oils are esters of long-chain fatty acids and glycerol. Esters of phosphoric acid are of the utmost importance to life. (For more information about fats\/oils and esters, see Chapter 17 \"Lipids\"<\/a>, Section 17.2 \"Fats and Oils\"<\/a>, and Section 15.10 \"Esters of Phosphoric Acid\"<\/a>, respectively.)<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n

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    Names of Esters<\/h2>\r\n

    Although esters are covalent compounds and salts are ionic, esters are named in a manner similar to that used for naming salts. The group name of the alkyl or aryl portion is given first and is followed by the name of the acid portion.\u00a0 It may be helpful to draw the structural formula in order to determine the alkyl\/aryl and acid portions.\u00a0 In both common and International Union of Pure and Applied Chemistry (IUPAC) nomenclature, the -ic<\/em> ending of the parent acid is replaced by the suffix -ate<\/em> (Table 15.3 \"Nomenclature of Esters\"<\/a>).<\/p>\r\n\r\n

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    Table 15.3<\/span> Nomenclature of Esters<\/th>\r\n<\/tr>\r\n
    Condensed Structural Formula<\/th>\r\nCommon Name<\/th>\r\nIUPAC Name<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
    HCOOCH3<\/sub><\/td>\r\nmethyl formate<\/td>\r\nmethyl methanoate<\/td>\r\n<\/tr>\r\n
    CH3<\/sub>COOCH3<\/sub><\/td>\r\nmethyl acetate<\/td>\r\nmethyl ethanoate<\/td>\r\n<\/tr>\r\n
    CH3<\/sub>COOCH2<\/sub>CH3<\/sub><\/td>\r\nethyl acetate<\/td>\r\nethyl ethanoate<\/td>\r\n<\/tr>\r\n
    CH3<\/sub>CH2<\/sub>COOCH2<\/sub>CH3<\/sub><\/td>\r\nethyl propionate<\/td>\r\nethyl propanoate<\/td>\r\n<\/tr>\r\n
    CH3<\/sub>CH2<\/sub>CH2<\/sub>COOCH(CH3<\/sub>)2<\/sub><\/td>\r\nisopropyl butyrate<\/td>\r\nisopropyl butanoate<\/td>\r\n<\/tr>\r\n
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    \"image\"<\/div><\/td>\r\n
    		ethyl benzoate<\/td>\r\nethyl benzoate<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n
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    Example 5<\/h3>\r\n

    Give the common and IUPAC names for each compound.<\/p>\r\n\r\n

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      [reveal-answer q=\"375945\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"375945\"]<\/p>\r\n

      1. The alkyl group attached directly to the oxygen atom is a butyl group (in green).<\/p>\r\n\r\n

      \"image\"<\/div>\r\n

      The part of the molecule derived from the carboxylic acid (in red) has three carbon atoms. It is called propionate (common) or propanoate (IUPAC). The ester is therefore butyl propionate or butyl propanoate.<\/p>\r\n

      2. An alkyl group (in green) is attached directly to the oxygen atom by its middle carbon atom; it is an isopropyl group. The part derived from the acid (that is, the benzene ring and the carbonyl group, in red) is benzoate. The ester is therefore isopropyl benzoate (both the common name and the IUPAC name).<\/p>\r\n\r\n

      \"image\"[\/hidden-answer]<\/div>\r\n<\/div>\r\n
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      Skill-Building Exercise<\/h3>\r\n

      Give the common and IUPAC names for each compound.<\/p>\r\n\r\n

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        \"image\"<\/div>\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
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        Example 6<\/h3>\r\n

        Draw the structure for ethyl pentanoate.<\/p>\r\n

        [reveal-answer q=\"745586\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"745586\"]Start with the portion from the acid. Draw the pentanoate (five carbon atoms) group first; keeping in mind that the last carbon atom is a part of the carboxyl group.\"image\"<\/p>\r\n

        Then attach the ethyl group to the bond that ordinarily holds the hydrogen atom in the carboxyl group.<\/p>\r\n\r\n

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        [\/hidden-answer]<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n

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        Skill-Building Exercise<\/h3>\r\n
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          Draw the structure for phenyl pentanoate.<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

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          Concept Review Exercises<\/h3>\r\n
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            From what carboxylic acid and what alcohol can isopropyl hexanoate be made?<\/p>\r\n\r\n<\/div><\/li>\r\n \t

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            From what carboxylic acid and what alcohol can cyclobutyl butyrate be made?<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n

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            [reveal-answer q=\"592836\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"592836\"]<\/p>\r\n\r\n

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            1. hexanoic acid and isopropanol<\/li>\r\n \t
            2. butyric acid and cyclobutyl alcohol[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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              Key Takeaway<\/h3>\r\n