Esters Flashcards
Outline the functional group of esters
-COOR
Outline the preparation reaction of esters
Carboxylic Acid + Alcohol -> Ester + Water
(Reversible)
Outline the conditions for the reaction of ester preparation
Reflux with concentrated CH2SO4
What type of reaction is the preparation of esters and why?
Condensation Reaction
-OH (R-COOH) + H+ (R-OH) -> H2O
How do you name esters? Give an example.
Ester = Prefix (-yl)
Acid = Suffix (-oate)
PropYL EthanOATE
Outline the solubility in water of esters
Small esters form H+ bonds with water
What happens to solubility of esters when the carbon chain increases?
Less soluble - C=O smaller effects
Large esters are immiscible (don’t mix, separate layers)
Outline the four uses (with examples) for the uses of esters
Solvents (e.g: ethyl ethanoate as glues)
Plasticizers/molecular lubricants (e.g: hexanedioic acid 50% plastics)
Food Flavourings (e.g: Octyl Ethanoate orange flavour)
Perfumes (e.g: Ethyl methanoate raspberry fragrance)
What intermolecular forces do esters have and why?
Dipole-Dipole and VDWs because they are polar
Which has a higher boiling point and why? Esters or Alkanes?
Esters - alkanes only have weak VDWs
Which has a higher boiling point and why? Esters or Alcohols/Carboxylic Acids?
Alcohols/Carboxylic Acids - esters don’t have H+ bonding so weaker IMFs so weaker BPTs
How can Esters be purified?
Purified from R-OH & -COOH by distillation
Which is the better method of hydrolysis of esters and why? With H2O or with dilute acid?
With dilute acid - H2O is too slow so never used
What is the hydrolysis with dilute acid reaction the opposite of?
Esterification
Ester + Water <(H+)> Carboxylic Acid + Alcohol
Why is the dilute acid used in the hydrolysis of esters?
H+ in acid makes carbonyl more susceptible to be attacked
What is another method of ester hydrolysis?
Hydrolysis with a base, NaOH
What is the reaction for the hydrolysis of esters with a base?
Ester + Sodium Hydroxide -(reflux)-> Alcohol + Sodium Salt of -COOH
What are Oils and Fats?
Esters of Glycerol + Fatty Acids
What are the differences between Oils and Fats?
Oils:
- Liquid at room temp
- Have more unsaturated fatty H+
Fats:
- Solid at room temp
- Contain mainly saturated fatty H+
Why are Oils liquid but Fats solid at room temperature?
Fats have strong VDWs (saturated=pack together)
Oils have weak VDWs (unsaturated less SA contact - far apart)
