ESTERS

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ESTERS AN ESTER IS SIMPLY AN OX YGEN BONDED BETWEEN TWO HYDROCARBON ATOMS. {

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ESTERS. AN ester is simply an oxygen bonded between two hydrocarbon atoms. {. GENERAL FORMULA. {. O R-C O-R’. Carbonyl Group. Alkyl Group or Aryl Group. - PowerPoint PPT Presentation

Transcript of ESTERS

Page 1: ESTERS

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Esters are derivatives of carboxylic acids in which the –OH of the carboxyl group has been replaced by an –OR from an alcohol.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)