Quote: Originally posted by njl  | C
seen plating out. If the Cu2+ is reduced to metallic copper, doesn't that imply that this process isn't catalytic?
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It is catalytic imo. U-Cu aka Urushibara copper
NEW HYDROGENATING CATALYSTS p203
The discovery of the Urushibara catalysts was due to the exploitation of a novel method for the reduction of estrone. Hence, we
shall begin with some of the earlier methods which are now of historical interest. The reduction of estrone, established in
this early period,3' involves the addition of precipitated nickel to an alkaline solution of estrone, to which aluminum chips are
then added to liberate hydrogen. It has subsequently developed that precipitated copper, in place of the
precipitated nickel, also gives estradiol-17/S in a good yield.27'
The modified method is the following: Zinc dust is added to 5 g of CuS04.5H20 dissolved in 100 ml of water, until the color
of the copper(II) ion disappears. The pre-cipitated copper is washed with water and added to 50 mg of estrone dissolved in 65
ml of 10% potassium hydroxide solution. The solution is heated on a water bath with stirring, while 3 g of aluminum
chips are added in small portions over a period of 10 hours. When the reaction is over, solid matter is filtered
off, and the filtrate, made acid with hydrochloric acid, is extracted with ether. From the extract, 40 mg of estradiol-17/3 is
obtained. Copper(II) chloride or copper(II) acetate may be used instead of copper(II) sulfate with almost the same result. A
further modification consists in the use of zinc dust in place of aluminum chips. Zinc dust (4 g) is added in one portion to
50 mg of estrone dissolved in 65 ml of 10% potassium hydroxide solution. The solution is heated on a water bath with stirring
and the precipitated copper, prepared from 5 g of copper(II) sulfate crystals and zinc dust, is added in small portions over a
period of 10 hours. The yield of estradiol-17/? is the same as in the former method.
US4273679 Aluminum alloys having a high reducing capacity and preparation thereof
ABSTRACT
This invention relates to a process for the preparation of
aluminum alloys having a high reducing capacity for
use in reductions in organic chemistry. According to
this method a discontinuous heterodisperse superficial
alloy is formed by subjecting an aluminum alloy pre
pared by a metallurgical process to superficial activa
tion and/or treating aluminum with a salt of a metal
having a greater normal electrode potential than that of
aluminum; whereby the solution of said metal in a protic
solvent is reacted with granular aluminum and/or an
aluminum alloy. The catalyst prepared according to the
invention is especially suitable for the reduction of a
nitro or nitroso group into an amino group. The aluminun alloys having a high reducing capacity are also
within the scope of the invention.
EXAMPLE 7
27 g. of aluminum grains (Al content 99%) are heated
in 200 ml. of 0.1 N hydrochloric acid with 3g of copper
powder for half an hour at 50° C. to 70° C. After cooling the metal is filtered off and may be used for reduction.
EXAMPLE 11
27 g. of aluminum grains (Al content 99%) are activated in 200 ml. of a 40% aqueous acetic acid solution
at 60° C. to 80° C. with 5 g. of cupric sulfate.
EXAMPLE 3
123. g. of nitrobenzene are dissolved in a mixture of 65
300 ml. of water and 300 ml. of methanol, whereupon
200 g. of an aluminum treated according to Example 1
are added. To the mixture 800 ml, of concentrated
hydrochloric acid are added under reflux, with stirring
and cooling within 90 minutes. After cooling the metal
is filtered off, the methanol is distilled off in vacuo and
about 200 g. of sodium chloride are added. After stand
ing for some hours the aniline can be separated. After
fractionation 85g. of aniline are obtained. Yield: 91%.
EXAMPLE 4
21.7 g of freshly prepared crystalline 1-phenyl-2,3-
dimethyl-4-nitroso-pyrazolone-5 are suspended in 200
ml. of ice cold water. 20 g. of aluminum grains-activated according to Example 5-are added, at a temperature between 0° C. and -10 C. under
stirring,whereupon 100 ml. of concentrated hydrochloric acid
are added dropwise. After 30 minutes the reaction mixture becomes colourless and the reduced product goes
into solution. The metal is filtered off. Thus 18.3 g of
1-phenyl-2,3-dimethyl-4-amino-pyrazolone-5 are obtained. Yield: 18.3.g., 90%.
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