Isomerism + carbonyl compounds Flashcards
(19 cards)
Define chiral carbon
Carbon that has 4 diff. groups attached to it
Define enantiomer
Non-superimposable mirror image
How do you test for optical isomerism?
- Shine plane polarised light
- 1 will rotate it clockwise
- 1 will rotate it anticlockwise
Define racemate
Contains equal quantities of each enantiomer
How do racemate mixtures form?
- C=O is planar
- Equal chances of nucleophile attacking either directions
- Equal amounts of each enantiomer will form
Outline the properties of esters
- Sweet smell - used for flavouring
- Polar so polar organic compounds dissolve in them
- Low BP so good solvent for ink + glue
- Plasticisers
What type of hydrocarbons do animal fats mainly have?
Saturated - long straight so strong VDW, high MP so solid
What type of hydrocarbons do vegetable oils mainly have?
Unsaturated - chain bent so weaker VDW, lower BP so liquid
What is needed to hydrolyse veg oil + animal fat to make glycerol, soap + FA?
3 Sodium hydroxide
What is biodiesel made up of?
Mixture of methyl esters
Acyl chloride names
What happens when an acid anhydride reacts w/ water, ammonia, alcohol + amine?
Same w/ acyl chloride but forms carboxylic acid instead of HCl
Why is acid anhydride used in industry instead of acyl chloride?
- Cheaper
- Safer - reacts slowly + doesn’t produce hydrogen chloride fumes
How do you remove water soluble impurities from a product?
- Seperation: pour mixture into seperation funnel, add water, organic layer + aqueous layer are immiscible so seperate into 2 layers
- Organic layer will end up w/ water so dry w/ MgSO4/CaCl2 (binds to water to become hydrated) - keep adding salt until it disperses then filter
How do you remove other impurities from a mixture?
- Washing
- E. add sodium hydrogen carbonate to mixture to remove acid, will give off CO2
What do you do when both the product + impurities are soluble in water?
- Solvent extraction
- Add organic solvent which product is more soluble in than water to mixture
- Product will dissolve in solvent leaving impurities dissolved in water
- Use seperating funnel
How do you purify volatile liquids?
- Distillation
- Connect condensor to round bottomed flask
- Place thermometer at neck of flask
- Heat
- Place flask at end of condensor to collect pure product
How do you purify organic solids?
- Recrystallisation
- Add hot solvent to impure solid until it dissolves - saturated solution of impure product
- Filter through heated funnel to remove insoluble impurities
- Leave sol to cool, crystals will form
- Remove liquid containing impurities from crystals by filtering mixture under reduced pressure - filter paper lined buchner funnel sitting in side arm flask attached to vacuum line
- Wash crystals w/ ice cold solvents to remove soluble impurities
Outline how impurities affect MP
Lowers MP + inc melting range
