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                        Palladium Catalyst faq rev 0.01
                        Channelled By : Randolph Carter
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1-Palladium on Carbon (charcoal)(5% Pd)

Prepare a solution of 1.7 g of Palladium Chloride (1)in 1.7 ml of concentrated
hydrochloric acid and 20 ml of water by heating on a water bath for 2 hours or
until solution is complete, and add this to a solution of 30 g of sodium acetate
trihydrate in 200 ml of water contained in a 500 ml hydrogenation flask. Add 20
g of acid washed activated charcoal (2) and hydrogenate in an atmospheric
hydrogenation apparatus (fig 1 to follow if yer lucky...)until absorption
ceases. Collect the catalyst on a buchner funnel and wash it with five 100 ml
portions of water and suck dry as possible. Dry the catalyst at room temperature
over potassium hydroxide pellets or anhydrous calcium chloride in a vacuum
dessicator. powder the catalyst (approx 20 g yield...)and store in a tightly
stoppered glass bottle, under a stump, by the creek, around the bend, close to
the edge, down by the corner.

2-Palladium on Carbon (charcoal) (30% Pd)

Prepare a solution of 8.25 g of palladium chloride(1) in 5 ml of concentrated
hydrochloric acid and dilute with 50 ml distilled water. Cool the solution in an
ice-salt bath and add 50 ml of 40% formaldehyde solution and 11 g of acid washed
activated charcoal(2). Stir the mixture mechanically and add a solution of 50 g
of potassium hydroxide in 50 ml water, keeping the temperature below 5 deg c.
When the addition is complete, raise the the temperature to 60 deg c for 15
minutes. Wash the catalyst thoroughly by decantation with water as above and
finally with dilute acetic acid, collect on a buchner filter and wash with water
free from chlorine or alkali. Dry at 100 deg c and store in a desiccator or
under a stump as above...

3-Palladium Black

Dissolve 5 g palladium chloride in 30 ml concentrated hydrochloric acid and
dilute with 80 ml water; cool in an ice-salt bath and add 35 ml 40% formaldehyde
solution. add a cold solution of 35 g potassium hydroxide in 35 ml water
dropwise during 30 minutes to the vigorously stirring palladium solution. Warm
to 60 deg c for 30 minutes and the wash the palladium precipitate six times by
decantation with water Filter on a sintered crucible, wash with 1 liter water
and suck dry (approx 3.1 g yield) and transfer to a dessicator charged with
silica gel or alternately under a stump as above.....


Notes:

(1) Alternately, the equivalent (molar) quantity of palladium chloride dihydrate 
    may bee used....

(2) Any of the commercial forms of activated charcoal/carbon ("Norit", "Darco",
    "Big K Brand", GNC etc...)may bee employed; the carbon should bee heated on 
    a steam bath with 10% nitric acid for 2-3 hours, washed free of acid with 
    water and dried at 100-110 deg c before use... 

All water used must bee high grade distilled totally free of chlorine/ other
halogens and alkali.

The sodium acetate dihydrate may bee prepared from vinegar/sodium hydroxide
reaction as covered elsewhere.

The 40% formaldehyde may bee substituted by use of a 37% solution instead or
preperation of your own solution in that neighborhood from parformaldehyde
heated in water as covered elsewhere/when....

The potassium hydroxide may bee obtained thru photo or alternately "wet" NiCad
battery outlets (dream of airplane and medical equipment battery suppliers...)

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Adam's Catalyst 

In a fume cupboard, dissolve chloroplatinic acid (H2PtCl6.6H2O, 0.10 g) in water
(ca. 0.5 ml) in a porcelain crucible (3-4 cm diameter). Add sodium nitrate (1 g)
and evaporate the mixture to dryness, over a low flame, with continuous
stirring. Turn the Bunsen burner full on and stir the contents of the crucible
vigorously until the mass has melted completely and the initial decomposition
has subsided. Keep the bottom of the crucible at a dull red heat for a further
30 min. (too strong a heat decomposes the oxide to the metal). Allow the
crucible to cool and wash the contents into a 250 ml. beaker with hot water from
a wash bottle. Filter off the brown platinum oxide with a small ('Hirsch')
funnel (Whatman paper No. 541) and wash the oxide with hot water (about 200 ml)
until the washings are free from nitrate ion. Dry the catalyst over calcium
chloride in a vacuum desiccator.

Palladium Black

Heat a mixture of palladium chloride (0.50 g) and water (100 ml) to 80deg.C and
carefully neutralise the suspension, to wide-range indicator paper, with 20%
sodium hydroxide solution (if the end point is overshot, palladium hydroxide
precipitates). Add 2.6% formic acid (2.5 ml) and, after about 2 min. make the
solution strongly alkaline with 20% sodium hydroxide solution (5 ml). Add more
of the formic acid (5 ml) and make sure that the solution is still alkaline.
Heat the mixture on a steam bath for 2 hours. Filter off the precipitate with a
small ('Hirsch') funnel (Whatman filter paper No. 541), wash it free from alkali
and dry it over calcium chloride in a vacuum desiccator.


5% Palladised Charcoal

Heat decolourising charcoal (7.5 g) on a steam bath for 2-3 hours with conc.
hydrochloric acid (5 ml) and water (150 ml). Wash the charcoal by decantation
with hot water until free of acid, filter it off, and dry it in an oven at
<100deg.C. Warm palladium chloride (0.5 g) in conc. hydrochloric acid (0.75 ml)
and water (5 ml) on the steam bath for ~ 20 min. Add the solution to AnalaR
sodium acetate (17.5 g) in water (50 ml) contained in a hydrogenation flask.
Introduce the purified charcoal (5.8 g) and hydrogenate the mixture until no
more hydrogen is absorbed (~ 2 h). The hydrogenation procedure is described
below. Collect the catalyst on a 7 cm Buchner filter (3 thicknesses of Whatman
No. 1 filter paper), wash it with water (5 x 100 ml) and drain it on the filter
with suction. Dry the catalyst over fresh silica gel in a vacuum desiccator and
store it in a tight stoppered bottle.


Lindlar's Catalyst (5% Pd on CaCO3, poisoned with Pb)

Stir calcium carbonate (precipitated, light; 1.1 g) in water (10 ml) in a flask
which is fitted with a thermometer and mounted on a magnetic stirrer/hotplate.
Whilst continuing the stirring, add palladium chloride (90 mg) to the suspension
and after 5 min., raise the temperature to 80deg.C for a further 10 min. Cool
the mixture and transfer it to a hydrogenation flask, using ~ 10 ml of water for
rinsing. Hydrogenate the mixture until hydrogen absorption (10-20 ml) is
complete (ca. 15 min); the hydrogenation procedure is described below. Collect
the reduced catalyst on a small 'Hirsch' funnel (Whatman filter paper No. 1) and
wash the catalyst with distilled water (20 ml). Add the damp catalyst to
distilled water (10 ml) in a flask on the magnetic stirrer/hotplate. Switch on
the stirrer, add a 5% (w/v) solution of AnalaR lead acetate in water (2 ml) and,
after 10 min., raise the temperature to 90deg.C for 40 min. During this time,
add distilled water, as necessary, to compensate for evaporation losses. Cool
the mixture, collect the catalyst on Whatman No. 1 paper in a small 'Hirsch'
funnel and wash the catalyst with distilled water (total, ~ 50 ml). Transfer the
catalyst to a clean, tared, specimen tube and dry the catalyst in a pistol at
40deg.C to constant weight (~ 1-3 h). Crush the dry catalyst to a powder with a
clean spatula or glass rod and stopper and label the tube (catalyst yield: 0.9-1 g).

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Preparation of Palladous Oxide (PdO) (Org Chem Coll Vol 2, p 566)

In a 350-cc. casserole, 2.2 g. (0.02 moles) of palladium metal is dissolved in 
a small amount of aqua regia, and the solution is treated with 55 g. of sodium 
nitrate and enough distilled water to make a thick paste. The substances are 
thoroughly mixed and then heated gently to drive off the water. The heating is 
increased until the mixture melts (about 270-280°C) and continued cautiously. 
Just above the melting point the mixture must be stirred and heated carefully 
as oxides of nitrogen are evolved and foaming occurs. After the evolution of 
gases is nearly complete (about five minutes) the full flame of a Bunsen burner 
is applied for about ten minutes. The entire time of heating should be about 
onehalf hour. As the mass cools, the casserole is rotated to allow the melt to 
solidify on the sides of the dish. After digestion with about 200 cc. of 
distilled water until the sodium salts are completely dissolved, the dark brown 
precipitate of palladous oxide is filtered and washed thoroughly with 1 per cent 
sodium nitrate solution (1). The oxide must not be washed with pure water since 
it shows a marked tendency to become colloidal. After drying in a vacuum desiccator 
the palladous oxide weighs 2.3-2.4 g. (91-95 per cent of the theoretical amount) (2).

(1) The filtrates should be clear and colorless; if they show a yellow-orange 
opalescence, some of the oxide has become colloidal. The palladium may be recovered (3) 
as the oxide by evaporating the filtrates to dryness and re-fusing, or as palladium 
black by rendering the filtrates slightly alkaline with sodium carbonate and heating 
with formaldehyde.

(2) A small amount of palladous oxide adheres to the casserole and cannot be removed 
by the ordinary means. The oxide is not dissolved readily by aqua regia but is easily 
removed by boiling with 48 per cent hydrobromic acid.

(3) See J. Am. Chem. Soc. 46, 1684 (1924) and Adams, J. Am. Chem. Soc. 47, 1147 (1925). 

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Rocketdoc:

Here are my instructions for Pd black from PdCl2 with borohydride.

Magnetically stirr the PdCl2 in water. If it does not dissolve, add a dash of HCL. 
100-200ml dH20 per 1g PdCl2 works fine. The solution should look like tea. Now 
add borohydride to the solution. The water immediately turns black. Add a little 
more borohydride and then stop stirring. Once the Pd black has settled, the water 
should be clear, and not tan colored anymore. If the color is still present, 
meaning all of the PdCl2 has not been reduced, then stirr some more and add more 
borohydride. The final color of the water should be clear. Filter the precipitate 
and wash with dH20.

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