• Esters are derivative from acids, prepared by the reaction of a Carboxylic acid and an alcohol.

• A way to distinguish esters from other organic families is by the “COOC” located within a chemical formula.

• In terms of pH Esters are neutral, or extremely close to neutral (do not change colour of litmus, phenolphthalein, methyl orange or any other acid-base indicator).

• Esters are colourless and exist in liquid state at room temperature.

• Polar due to the presence of the carbonyl group (mainly because of the C=O) and act as hydrogen acceptors, not as donors. This ability to participate in hydrogen bonding allows for some solubility in water.

• Esters are volatile in nature, more then carboxylic acids

• Because of their lack of hydrogen-bond-donating ability, esters do not self-associate.

• An important fact is that the boiling point, melting point and solubility of the straight chain isomers of esters are lower than those of branched chain isomers. The larger the structure gets the higher the boiling point.

Example of a simple straight chain isomer

Example of a simple branched chain isomer

• The boiling point of the simple ester CH3COOCH2CH3 is 77.1°C

Chemical Boiling point

Ethyl butanoate 121 °C

Ethyl 2-methylbutanoate

133 °C

Branched VS. Straight

(Not Esters)

Ester names consist of two words. Use the alkyl portion of the alcohol name

first.(The carbon chain NOT double bonded to an oxygen)

The -ic acid ending of the name of the carboxylic acid is replaced with –ate and follows the first name.

(The carbon chain that IS double bonded to one OR MORE oxygen)

Methyl Propanoate

Diester

•Two butyls off the ends •Proponate in the center • Dibutyl Propanedioate (Di = two double bonded oxygens )

Esterification A condensation reaction

Carboxylic acids are recognized as organic acids (-COOH)

+ An alcohol compound recognized as a base by the (-OH) in it’s formula

→→→Factors involved in the reaction: Heat and an acidic catalyst such as the commonly used H2SO4

Esterification

NOTE: The concentration of water is ALWAYS derived from the (-OH) in the acid and the (-H) in the alcohol

Ester Formula Line Drawing Solubility (g per 100 mL of water)

ethyl methanoate

HCOOCH2CH

3

10.5

ethyl ethanoate

CH3COOCH2

CH3

8.7

ethyl propanoate

CH3CH2COOCH2CH3

1.7

Solubility in Water

In Summary: The longer the carbon chain the less soluble the ester is.

Polarity Ranking of the Functional Groups(most polar first):

Amide > Acid > Alcohol > Ketone ~ Aldehyde > Amine > Ester > Ether > Alkane

• The polarity of the ester molecules causes them to be attracted to one another and this intermolecular attraction requires more energy (heat) for the esters to transfer from a liquid to a gaseous state.

• Polarity also causes the ester molecules to be attracted to positively charged metal surfaces. As a result, the molecules tend to line up on the metal surface creating a film, which somewhat acts as a lubricant.

• The polar nature of esters also makes them good solvents, which allows them to disperse oil products(such as varnish).

• Esters with low molecular weight are commonly used as fragrances and found in essential oils

Esters in Synthetic Lubricants The Hatco Corporation

Esters have been used successfully in lubrication for more than 50 years. For example, esters have been used exclusively in jet engine lubricants worldwide due to their unique combination of low temperature ease of flow with clean high temperature operation.

Artificial fruit flavours in foods

Esters have been use in all food products containing artificial flavouring for years. They create distinct flavours and aromas which is what often sells the product. Flavours: Orange – octyl ethanoate, grape- ethly heptanoate, banana- 3-methlybutyl ethanoate, and etc. Also used as fruity flavours for foods and drinks such as milkshakes, ice-cream, chewing gum, jellies, sweets and cakes.

An industrial use of esters include the production of oils, such as bio diesel. Bio diesel is made using fatty acids (a carboxylic acid) taken from the seeds of plants and methanol (an alcohol). Heat and a concentrated acid is then used to quicken the reaction process. Linolenic acid and methanol are used to create bio diesel. Linolenic acid is found in vegetable or animal fats. As well as bio diesel being produce, small amounts of glycerine are also produced.

Condensation is emitted

Hydrolysis

The reverse of Esterification

Ester + Acid → Carboxylic Acid + Alcohol

Ester + Base → Carboxylic Acid + Alcohol

Floral and fruity perfumes also contain esters, as well as air fresheners. When produced properly, esters have a very pleasant and powerful scent

Saponification is a process that produces soap, usually from fats. Saponification involves a base (usually caustic soda NaOH), heat, and the hydrolysis of esters, to form the sodium salt of a carboxylate, which we call soap.

R- Carbon chain of a fatty acidR’- carbon chain of an alcohol

Type of Reaction

Reactant 1

Reactant 2

Sample Reaction Special Conditions

Condensation(Dehydration)

Carboxylic acid

Alcohol Heat and Concentrated acid

Hydrolysis Ester Water Heat and Catalyst

Delmar. Chemwiki: The dynamic chemistry textbook. Retrieved from http://chemwiki.ucdavis.edu/Organic_Chemistry/Esters/Nomenclature_of_Esters

Clark, J. (n.d.). Retrieved from http://www.chemguide.co.uk/organicprops/esters/background.html

Ophardt, C. (n.d.). Retrieved from http://www.elmhurst.edu/~chm/vchembook/213organicfcgp.html

http://www.vvc.edu/academic/chemistry/Unit%209R%20-%20Carboxylic%20Acids.pdf

http://www.perkinelmer.com/pdfs/downloads/APP_FAMEbyGCinB100Biodiesel.pdf

http://chemistryhelp.zohosites.com/Physical-Properties-of-Esters.html