Grignard's Reagent Flashcards
1
Q
What is the structure of a Grignards reagent?
A
R-Mg-X
2
Q
What are Grignards reagents used for?
A
To lengthen the carbon chain
3
Q
How would a Grignards reagent be prepared?
A
- Refluxing under anhydrous conditions
- Water bath around 40C
- Vertical condenser
- Haloalkane is added to reaction flask, along with Mg turning and diethyl ether
4
Q
How do we prevent the addition of water when preparing a Grignards reagent?
A
- Dry all apparatus in an oven prior
- Add an anhydrous calcium chloride drying tube to the top of the condenser
5
Q
Why does the addition of water need to be prevented?
A
Grignards reagents react with water to produce alkanes.
6
Q
What is the purpose of diethyl ether in the reaction?
A
- solvent
- aprotic, water or alcohols would protonate Grignards to produce a hydrocarbon (not what we want)
- C-O is polar, allowing the oxygen to solvate and stabilise the Mg ion
7
Q
What is the most common reaction using a Grignards reagent?
A
Addition of the R to the central carbon, addition of MgX to O. Protonation using H+/H2O to substitute MgX with H.
