Condensation & Redox - Organic Reactions & Mechanisms (8.3) Flashcards
Give 2 types of condensation reactions
Esterification
Amide/Protein synthesis
Give the reactants used in esterification
Alcohol
+ Carboxylic acid derivative
+ Catalyst
Give the reactants used to make amides (proteins)
Amine
+ Carboxylic acid derivative
+ Catalyst
In organic chemistry what is usually being oxidised or reduced?
Carbon
Give an alternative definition of oxidation (not to do with adding/removing electrons)
Addition of oxygen
OR
Removal of hydrogen
Give an alternative definition of reduction (not to do with adding/removing electrons)
Loss of oxygen
OR
Addition of hydrogen
Give an example of an oxidising agent
Acidified potassium dichromate
Describe the colour change from Cr(VI) -> Cr(III)
Orange -> Green
Give an example of 2 reducing agents
Lithium aluminium hydride (LiAlH4) & Sodium borohydride (NaBa4)
Give an advantage and disadvantage of using LiAlH4 as a reducing agent
+ Very reactive
- Requires dry solvent
Give an advantage and disadvantage of using NaBH4
+ Does not need dry conditions
- Won’t reduce carboxylic acids
What can we use to symbolise oxidising & reducing agents in organic chemistry?
[O] (oxidising agent)
[H] (reducing agent)
Ketones can be oxidised. True or false?
False. Ketones cannot be oxidised
Tertiary alcohols cannot be oxidised. True or false?
True
What are the main uses of the potassium dichromate test?
- Oxidation gives a positive test for aldehydes & 1°/2° alcohols
- It can distinguish between 1°/2° and 3° alcohols
- It can distinguish between aldehydes & ketones
How do you test for aldehydes using Fehling’s solution?
Blue sol -> red/orange ppt
How do you test for aldehydes using Tollen’s reagent?
[Ag(NH3)2+)])
Colourless sol -> gives silver mirror (solid Ag)
What happens to ketones in Fehling’s solution?
No change (remains blue)
What happens to ketones in Tollen’s reagent?
No change (remains colourless)
How do you make aldehydes?
- Primary alcohols are oxidised under reflux
- A reflux allows us to boil the solvent without it evaporating
- The aldehyde is removed by distillation before it is oxidised before it is oxidised further
How do you make ketones?
- Secondary alcohols are oxidised under reflux
- A reflux allows us to boil the solvent without it evaporating
What happens if you heat the reaction with primary alcohols strongly?
Carboxylic acid is formed
