SYNTHESIS NO.43
Bis dimethylglyoximato nickel (II)
1.
Weigh, to the nearest 0.01 g, 2 g of NiCl2 • 6H2O. Place in a 1000 ml round bottom flask.
Support the round bottom flask in a cork ring so it won’t roll over. Add 500 ml H2O and swirl
until the salt dissolves.
2.
Using a 10 ml pipet, add 5.5 ml of dilute (3N) HCl. Mix thoroughly.
3.
Weigh, to the nearest 0.01 g, 2.2 g dimethylglyoxime. It is important that an excess of this
reagent is not used, as it will cause premature precipitation of the product. Place the reagent in
a 250 ml flask and add 150 ml n-propanol. Place the flask on a hot plate and heat until the
dissolution occurs. This will require frequent swirling. After dissolution, place the flask in an
ice and water bath and cool to 25º C.
4.
Weigh, to the nearest 0.1 g, 35 g urea. Place the reagent in the 1000 ml flask and swirl to
dissolve.
5.
Slowly add, with swirling, the dimethylglyoxime solution to the nickel solution. Use about 10
ml of n-propanol to rinse the transfer flask.
6.
Place the flask on a steam bath, removing as many of the metal rings as possible.
7.
Place a small watch glass on the flask to prevent excessive loss of solvent.
8.
Allow the solution to heat for approximately 1.5 hours. Monitor the solution during the first 10
minutes of heating. Small red crystals will start to form in the solution at this time; however,
there should not be a dense red precipitate.
9.
At the end of the heating period, check the pH of the solution with a piece of hydrion paper.
The pH of the solution should be 7-8 . If the solution is still acidic, heat for an additional 20
minutes and recheck the pH.
10.
Filter off the product, using a 150 ml M sintered glass filter funnel. Use some of the filtrate to
rinse the boiling flask.
11.
Wash the product with two small (10 ml) portions of acetone. Suction dry the product and
place in a pre-weighed vial (with cap).
12.
If the sintered glass funnel is dirty, rinse it under suction with dilute hydrochloric acid and then
distilled water.
H3C
N
:
N
:
HO
CH3
dimethylglyoximato
O-