Inorganic Chemistry (300899) Experiment 3.4 Report Preparation of Vanadium Acetylacetonate Introduction:

Acetylacetone exists in two tautomeric forms Keto and enol. It is a weak acid and is mainly found in enol form. Acetyacetone is a bidentate ligand. The ligand binds to the transition metal ion in such a way that, one oxygen atom from the carbonyl group is bonded via covalent bond and the other via dative bond.

The two hydrogen atoms attached to the α-Carbon, (the centre carbon (CH2) that is linked to the carbonyl groups) are acidic. The α-hydrogen can easily be lost to water thus, producing an anion. Only after Acetylcetone becomes deprotonated, it can act as a ligand and form a Blue-Green, five-coordinated Acetylacetonate complex with Vanadium (IV).

Aim:
To synthesise Vanadium (IV) Acetylacetonato complex, using vanadium (V) as a starting material.

Experimental:
1. Add 10 ml of water, 5 ml of concentrated sulfuric acid and 15 ml of ethanol to 2.5 g of Vanadium (V) oxide in a 200ml beaker.
2. Cover the beaker with watch glass and heat on steam bath for about 30 min, stirring frequently.
3. Filter off the mixture, using a Buchner funnel and transfer it to 400ml beaker using approximately 20ml of water.
4. Add 6.2 ml of Acetylacetone, then slowly add the sodium carbonate solution (10g in 60ml water).
5. Keep adding until the solution is neutralized, this is determined by using a pH paper.
6. Filter off the product using Buchner funnel, wash with water, then ethanol and dry it thoroughly.
7. Weigh the product and calculate percentage yield.
Results:
Calculations:
Weight of V2O5 used: 2.5 g Moles of V2O5 used: 2.5 / (50.94 x 2)