Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

USB OF NICKEL 379
Preparation of Platinum Oxide, PtO2 1
Platinum oxide catalyst prepared by the method of R. Adams has
recently come into use because it is very convenient to prepare and
handle and at the same time has very high activity. When in use it is
first reduced by hydrogen in the hydrogenation bulb to very finely
divided platinum.
Dissolve 2-1 g. of platinic chloride (H2PtCl6) in 5 c.c. of water
in a large porcelain crucible, mix with 20 g. of pure sodium nitrate,
and evaporate the water over a small flame, stirring continuously
with a thick glass rod. Then gradually raise the temperature until
the contents of the crucible are completely fused. Nitrogen peroxide
is evolved. Meanwhile, by heating with two powerful Bunsen
burners, raise the melt to moderate red heat (500-600°). Evolution
of NO2 decreases greatly after five to ten minutes. Allow to cool,
extract with distilled water, wash the heavy residue several times by
decantation, filter at the pump, and dry in a desiccator. Platinum
oxide so produced should have a moderately dark-brown colour.
2. CATALYTIC HYDROGENATION WITH NICKEL.
CYCLOHEXANOL *
Half a porous plate is broken into pieces the size of small peas
and the fragments, after being mixed with a solution of 40 g. of
chlorine-free nickel nitrate in 20 c.c. of water, are dried, with stirring,
on the water bath. The impregnated material is then heated at dull
redness in a nickel crucible until evolution of oxides of nitrogen
ceases and filled into a combustion tube (leaving at each end 10 cm.
empty).
The tube is then heated in a slightly sloping bomb furnace, or,
better, in an electric resistance furnace, 3 while a stream of hydrogen,
which is washed with saturated permanganate solution and dried in
two wash-bottles containing concentrated sulphuric acid, is passed
through. An adapter is fitted to the other end of the tube and afterwards,
when the nickel oxide has been reduced, is kept with its
point dipping into a vessel containing concentrated sulphuric acid
(to prevent the entrance of air).
1 J. Amer. Chem. Soc., 1922, 44, 1397 ; 1923, 45, 2171.
2 Sabatier, Gompt. rend., 1903, 173, 1025.
8 Such furnaces can easily be constructed from simple materials. See, for
example, H. Rupe, Helv. Chim. Acta, 1918, 1, 454; Chem. Fabr., 1929, 50, 519-
Cf. also Handbuch der Physik, H. Geiger and K. Scheel, 11, 370 et seq.