{"id":1615,"date":"2018-03-21T15:32:50","date_gmt":"2018-03-21T15:32:50","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/chapter\/hydrolysis-of-esters\/"},"modified":"2018-11-08T19:44:32","modified_gmt":"2018-11-08T19:44:32","slug":"hydrolysis-of-esters","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/hydrolysis-of-esters\/","title":{"raw":"15.9 Hydrolysis of Esters","rendered":"15.9 Hydrolysis of Esters"},"content":{"raw":"
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Learning Objectives<\/h3>\r\n
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  1. Describe typical reactions that take place with esters.<\/li>\r\n \t
  2. Identify the products of an acidic hydrolysis of an ester.<\/li>\r\n \t
  3. Identify the products of a basic hydrolysis of an ester.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nEsters are neutral compounds, unlike the acids from which they are formed. In typical reactions, the alkoxy (OR\u2032) group of an ester is replaced by another group. One such reaction is <\/span>hydrolysis, <\/span>the reaction of a substance with water<\/span><\/span>, literally \u201csplitting with water.\u201d The hydrolysis of esters can be catalyzed by either an acid or a base, with somewhat different results.\r\n<\/span>\r\n\r\n<\/div>\r\n<\/div>\r\n
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    Acidic hydrolysis is simply the reverse of esterification. The ester is heated with a large excess of water containing an acid catalyst. Like esterification, the reaction is reversible and does not go to completion.<\/p>\r\n\r\n

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

    As a specific example, butyl acetate and water react to form acetic acid and 1-butanol.<\/p>\r\n\r\n

    \r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1500\"]\"image\" (Note: Butyl acetate should have one more CH2<\/sub> in the green part,\u00a0 Also, the second to the last C in the green part should be CH2<\/sub> not CH3<\/sub>. \u00a0 MK)[\/caption]\r\n\r\n<\/div>\r\n
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    Example 7<\/h3>\r\n

    Write an equation for the acidic hydrolysis of ethyl butyrate (CH3<\/sub>CH2<\/sub>CH2<\/sub>COOCH2<\/sub>CH3<\/sub>) and name the products.<\/p>\r\n

    [reveal-answer q=\"325649\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"325649\"] In acidic hydrolysis, water (HOH) splits the ester bond. The H of HOH joins to the oxygen atom in the OR part of the original ester, and the OH of HOH joins to the carbonyl carbon atom:<\/p>\r\n\r\n

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    The products are butyric acid (butanoic acid) and ethanol.[\/hidden-answer]<\/p>\r\n\r\n<\/div>\r\n

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    Skill-Building Exercise<\/h3>\r\n
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      Write an equation for the acidic hydrolysis of methyl butanoate and name the products.<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

      When a base (such as sodium hydroxide [NaOH] or potassium hydroxide [KOH]) is used to hydrolyze an ester, the products are a carboxylate salt and an alcohol. Because soaps are prepared by the alkaline hydrolysis of fats and oils, alkaline hydrolysis of esters is called saponification from the <\/span><\/span>Latin sapon<\/em>, meaning \u201csoap,\u201d and facere<\/em>, meaning \u201cto make\u201d. In a saponification reaction, the base is a reactant, not simply a catalyst. The reaction goes to completion:<\/p>\r\n\r\n

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

      As a specific example, ethyl acetate and NaOH react to form sodium acetate and ethanol:<\/p>\r\n\r\n

      \"image\"<\/div>\r\n
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      Example 8<\/h3>\r\n

      Write an equation for the hydrolysis of methyl benzoate in a potassium hydroxide solution.<\/p>\r\n

      [reveal-answer q=\"815592\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"815592\"] In basic hydrolysis, the molecule of the base splits the ester linkage. The acid portion of the ester ends up as the salt of the acid (in this case, the potassium salt). The alcohol portion of the ester ends up as the free alcohol.<\/p>\r\n\r\n

      \"image\"[\/hidden-answer]<\/div>\r\n<\/div>\r\n
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      Skill-Building Exercise<\/h3>\r\n
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        Write the equation for the hydrolysis of ethyl propanoate in a sodium hydroxide solution.<\/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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          How do acidic hydrolysis and basic hydrolysis of an ester differ in terms of<\/p>\r\n\r\n

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          1. products obtained?<\/li>\r\n \t
          2. the extent of reaction?<\/li>\r\n<\/ol>\r\n<\/div><\/li>\r\n \t
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            What is saponification?<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n

            \r\n\r\n[reveal-answer q=\"907968\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"907968\"]\r\n\r\n1. a. acidic hydrolysis produces carboxylic acid + alcohol; basic hydrolysis produces carboxylate salt + alcohol\r\n\r\nb. Basic hydrolysis goes to completion; acidic hydrolysisis reversible, resulting in a mixture of the ester and the caboxylic acid and the alcohol. [\/hidden-answer]\r\n\r\n<\/div>\r\n<\/div>\r\n
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            Key Takeaways<\/h3>\r\n<\/div>\r\n
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