ESTERS
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Transcript of ESTERS
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ESTE
RS
AN EST
ER IS
SIM
PLY
AN OXYG
EN B
ONDED
BETW
EEN T
WO H
YDROCARBON A
TOM
S.
{
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GENERAL FORMULA
OR-C
O-R’Alkyl Group or Aryl Group
Carbonyl Group{
The R groups can be short-chain or long –chain aliphatic (alkyl) or aromatic (aryl) groups, saturated or unsaturated.
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WHAT ARE ESTERS
Esters are derivatives of carboxylic acids in which the –OH of the carboxyl group has been replaced by an –OR from an alcohol.
Esters contain a carbonyl group and an ether link to the carbonyl carbon.
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MORE ABOUT ESTERS
Although the molecules are polar, they cannot form hydrogen bonds with one another because they do not contain hydrogen attached to oxygen or another electronegative atom.
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ESTERIFICATION
R–C
OH
O
+ RO H O
R
OR–C + H -
OH
H+
Carboxylic Alcohol Carboxylate Water Acid EsterEsters mainly result from the condensation (water producing reaction) of a carboxylic acid and an alcohol. The process is called esterification. This reaction can be catalyzed by the presence of H+ ions. Sulphuric acid, (H2SO4) is often used as a catalyst for this reaction.
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PROPERTIES
They have much lower boiling points than the strongly hydrogen-bonded carboxylic acids from which they are derived from.
The low formula-mass esters are somewhat soluble in water, but esters containing more than four or five carbons have very limited solubility.
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NAMING
The format is as follows:
(alkane further from carbonyl) (alkane closest to carbonyl) (parent chain)
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Step 1: Identify the alkyl group attached to the oxygen atom.
In this case, it is methyl attached to the oxygen because there is only one carbon.
General Formula
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Step 2: Determine the acid present, and change the stem name from –oic to –oate.
Methyl Methanoate
The acid attached is methanol, only have one carbon. Creating methanoate.
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EXAMPLE #1
1) First you identify the alkyl group attached to the oxygen.
2) Identify the alkane that attaches the carbon atoms.
3) Replace the –oic ending with an –oate ending
4) NOTE: You name the structure backwards from how its written.
Ethyl Ethanoate
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EXAMPLE #2
Methyl Ethanoate
1) Name the alkane farthest from theCarbonyl group first (Methyl)
2) Name the alkane attaching the Carbons (or carbonyl group) (Ethyl)
3) Change the ending to –oate.
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MORE EXAMPLES
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Many Esters give blueberries, pineapples, apples, pears, bananas and many other fruits there characteristic aromas.
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RaspberriesHCOOCH2CH3 ethyl methanoate (IUPAC) ethyl formate (common)
Pineapples CH3CH2CH2COOCH2CH3 ethyl butanoate
(IUPAC) ethyl butyrate
(common)