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Esters introduction information
Naming and properties of Esters
15
Organic Chemistry
Undergraduate 2
02/28/2015

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Term
How are Esters formed?
Definition
When a carboxylic acid reacts with an alcohol to form an ester and a water.  The -H from the carboxylic acid is donated and an alkyl group replaces it.
Term
What is Esterification?
Definition

An ester is produced when a carboxylic acid and an alcohol react in the presence of an acid catalyst (H2SO4)

The -OH is removed from the carboxylic acid and the -H is removed from the alcohol to form the ester and water.

  O                                                 O                

       ||                                                ||                     

CH3-C-OH + H-O-CH3 (acid) Heat->CH3-C-O-CH3 + H2O

Ethanoic Acid + Methanol -> Methyl acetate + H2O

Term
What is the IUPAC naming for Esters?
Definition

The first word is te alkyl part of the alcohol.  The second word is the carboxylate name of the carboxylic acid (-ic replaced with -ate)

Methanol + Ethanoic Acid -> Methyl Ethanoate

    O

     || 

CH3-O-C-CH3

Term
What are common names for esters?
Definition

Use the  alkyl name of the alcohol and the common name of the acids.

Methyl alcohol + Acetic Acid = Methyl Acetate

     O

     || 

CH3-O-C-CH3

Term
What are the boiling points of Esters?
Definition

Higher than alkanes, lower than alcohols and carboxylic acids.  No hydrogen bonding is present.

Alkane -> Ether -> Ester -> Alcohol -> Carboxylic Acid

Term
Are esters soluble in water?
Definition
Smaller esters are due to the partial negativty of oxygen.  Carbonyl can form hydrogen bonds with water.
Term
What is acid hydrolysis of esters?
Definition

Esters are split when heated in a strong acid in the presence of water. 

O                                           O             

         ||                                           ||                       CH3-C-O-CH3 + HOH (acid) -> CH3-C-OH + CH3-OH

Methl ethanoiate + water -> Ethanoic Acid + Methanol

Term
What is Saponification?
Definition
The base hydrolysis of esters.
Term
How does Saponification work?
Definition

The reaction of a long chain fatty acid with NaOH to make soap.  The carboxylic acid produced in acid hydrolysis is converted to its carboxylate ion by a strong base.

 O                                             O                    

||                                            ||                   

CH3-C-O-CH3 + NaOH [Heat]-> CH3-C-O-Na+ + CH3-OH

Methyl Ethanoate + Sodium hydroxide ->               Sodium Ethanoiate + Methanol

Term
What is a soap?
Definition
A salt made of long chain fatty acids.  The soap molecule ends have different polarities.
Term
What is the polarity and solubility of the carbon chain of a soap molecule?
Definition
Non-polar and hydrophobic.  Soluble in oil and grease.
Term
What is the polarity and solubility of the carboxylate salt end of a soap molecule?
Definition
Ionic, hydrophilic and soluble in water.
Term
How does soap function?
Definition
The nonpolar ends dissolve in nonpolar fats and ols on dirt.  The carboxylate salt ends dissolve in water.
Term
What are micelles?
Definition
Clusters of coated oil and grease.  The ionic ends of the soap molecules provide polarity and makes them water soluble.  The coated glbules are pulled into water and are rinsed away.
Term
What is a problem using soap?
Definition
The carboxylate end reacts with calcium and magnesium to form insoluble substances.
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