Formula of ester

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Structure of esters To make an ester, a hydrogen atom must be removed from the hydroxyl group (–OH) of the alcohol. The –OH portion of the acid's carboxyl group must also be removed. The hydrogren atom and the -OH combine to form a water molecule (H 2 O). \[propanol + ethanoic\,\,acid \rightleftharpoons propyl\,\,ethanoate + water\] This same change can be represented using shortened structural formulae: \[CH_O\] When looking at the structure of an ester, you can easily name it. Remember that the C=O part of the molecule came from the acid. In the molecule below, the ester link (-COO) separates the two parts of the molecule. Since the C=O came from the parent acid, there were four carbon atoms in the acid molecule (butanoic acid) and two carbon atoms in the parent alcohol (ethanol). This ester is called ethyl butanoate . The names and structures of some other esters are shown below.

Figure 15.4 The Structure of Esters. Esters feature a carbon-to-oxygen double bond that 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). 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. Names of Esters 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. In both common and International Union of Pure and Applied Chemistry (IUPAC) nomenclature, the – ic ending of the parent acid is replaced by the suffix – ate ( Table 15.3 Nomenclature of Esters Condensed Structural Formula Common Name IUPAC Name HCOOCH 3 methyl formate methyl methanoate CH 3COOCH 3 methyl acetate methyl ethanoate CH 3COOCH 2CH 3 ethyl acetate ethyl ethanoate CH 3CH 2COOCH 2CH 3 ethyl propionate ethyl propanoate CH 3CH 2CH 2COOCH(CH 3) 2 isopropyl butyrate isopropyl butanoate The part of the molecule derived from the carboxylic acid (in red) has three carbon atoms. It is called propionate (...

https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FPurdue%2FPurdue%253A_Chem_26200%253A_Organic_Chemistry_II_(Wenthold)%2FChapter_18._Carboxylic_Acid_Derivatives%2F18.01%253A_Structure_and_Nomenclature_of_Acid_Derivatives%2FEsters%253A_Structures_and_Names Learning Objectives • Identify the general structure for an ester. • Use common names to name esters. • Name esters according to the IUPAC system. Esters have the general formula RCOOR′, where R may be a hydrogen atom, an alkyl group, or an aryl group, and R′ may be an alkyl group or an aryl group but not a hydrogen atom. (If it were hydrogen atom, the compound would be a carboxylic acid.) Figure \(\PageIndex\): The Structure of Esters. Esters feature a carbon-to-oxygen double bond that 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). 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. Fats and vegetable oils are esters of long-chain fatty acids and glycerol. Esters of phosphoric acid are of the utmost importance to life. Solution The al...