Esters and Esterification

C11-5-20 FUNCTIONAL GROUPS Vocabulary & Concepts Esterification OUTCOME QUESTION(S): C11-5-20 FUNCTIONAL GROUPS Name and write structural models for and name alkyl halides. Name and write structural models for common alcohols and describe uses. Name and write structural models for common acids Name and write structural models for common esters and investigate importance. Vocabulary & Concepts Esterification

Esters account for some natural and artificial flavours and odors The functional group of esters is the ester group. Made up of two smaller functional groups General formula: R–COOR’ R - hydrocarbon chain from the acid R' - hydrocarbon chain from the alcohol carbonyl group O C R Esters account for some natural and artificial flavours and odors R' alkoxy group made by combining carboxylic acid and alcohol

O CH3CH2-C \ O-CH2CH2CH3 // Properties of Esters: alcohol acid Polar covalent: < 5C are soluble in water Strong IMF (dipoles) gives high bp/mp But not as strong as alcohols and acids O C R δ- δ+ R' The double-bonded oxygen part of the compound came from the acid…the other branch, the alcohol CH3CH2-C O \ O-CH2CH2CH3 // alcohol acid

When you analyze the compound left to right, the acid is always first Naming Esters Identify the acid part of the compound. Change acid ending from – oic acid to – oate 2. Identify the alcohol part of the compound. Change alcohol name into a branch – yl Written as two names When you analyze the compound left to right, the acid is always first acid alcohol CH3CH2CH2CH2COOCH2CH3 5 4 3 2 1 1 2 ethyl pentanoate

Esters are complex enough… Name the following compounds: Esters are complex enough… we won’t add branches HC OCH2CH3 O ethyl methanoate rum acid CH3C – OCH2CH2CH3 O acid alcohol alcohol propyl ethanoate pear acid alcohol CH3CH2CH2COOCH2CH2CH2CH2CH3 pentyl butanoate peaches

Draw the following compounds: Draw the acid first HC OCH3 O methyl methanoate acid alcohol H3C – C – OCH2CH2CH2CH3 O butyl ethanoate acid alcohol CH3CH2CH2CH2CH2COOCH2CH2CH3 propyl hexanoate acid alcohol

Making Esters: Esterification Esterification is a reversible reaction CH3CH2-C O \ OH // CH3CH2-C O \ O-CH2CH2CH3 // acid ester de esterification reaction + + H2O CH3CH2CH2OH water alcohol This is our first look at organic reactions – there are more coming

CH3-C O H CH3-C O H HO-CH3 O-CH3 O H Esterification between ethanoic acid and methanol: Ester (methyl ethanoate) CH3-C O H CH3-C O + H HO-CH3 O-CH3 O H Ethanoic acid Methanol The key here is to write the alcohol “backwards” to help visualize water leaving… water

Write the esterification reaction for the reaction between pentanoic acid and 1-butanol. CH3CH2CH2CH2-C O \ OH // water Pentanoic acid HOH + + CH3CH2CH2CH2-C O \ O-CH2CH2CH2CH3 // HOCH2CH2CH2CH3 1-butanol butyl pentanoate

Draw this esterification ALL in condensed formula… Write the esterification reaction for the reaction between butanoic acid and methanol. water CH3CH2CH2COOH butanoic acid HOH + + HOCH3 CH3CH2CH2COOCH3 methanol methyl butanoate Draw this esterification ALL in condensed formula…

Consider the alcohol propane-1,2,3-triol (glycerol) An ester at each hydroxyl group creates a tri-ester Called triglyceride – the main constituent of fat H2C–OOC(CH2)14CH3 HC–OOC(CH2)14CH3 H2C–OH HC–OH HOOC(CH2)14CH3 Depending on the number of double-bonds in the acid chains that create the tri-ester, triglycerides can be saturated, mono-unsaturated or polyunsaturated.

C11-5-20 FUNCTIONAL GROUPS Vocabulary & Concepts Esterification CAN YOU / HAVE YOU? C11-5-20 FUNCTIONAL GROUPS Name and write structural models for and name alkyl halides. Name and write structural models for common alcohols and describe uses. Name and write structural models for common acids Name and write structural models for common esters and investigate importance. Vocabulary & Concepts Esterification