In a
hood a
2-l., wide-mouthed Erlenmeyer flask containing 600 ml. of distilled water is placed in an empty
water bath and fitted with an efficient stainless steel stirrer, so that its blades are half immersed. The stirrer is started, and
160 g. of sodium hydroxide is dissolved in the water. Then
125 g. of 1:1 aluminum-nickel alloy (Note
1) is added in portions as rapidly as possible, but at such a rate that no material is lost by frothing with the stirrer running at full speed (Note
2). When all the alloy has been added the stirrer is slowed down, and the catalyst is washed down from the sides of the flask with distilled water. As soon as the reaction has subsided the water bath is filled with boiling water, and the catalyst is slowly stirred while the volume is kept up by the occasional addition of distilled water so that the catalyst is well covered at all times. After 6 hours, stirring and heating are discontinued, and the catalyst is allowed to stand at room temperature for 12–15 hours. It is then washed by decantation with ten 250-ml. portions of distilled water and transferred to a
1-l., round-bottomed, three-necked flask by means of distilled water. The total volume of catalyst and water is adjusted to 300 ml., and the flask placed in a cold water bath which is equipped with a
thermometer. One side arm is fitted with a
100-ml. dropping funnel, and the other two necks are each connected to a
3-l. Büchner flask by short lengths of thick-walled, wide-bore rubber tubing (Note
3), (Note
4). One of the Büchner flasks is connected to a vacuum gauge and then to an efficient
water pump. The other Büchner flask is connected directly to a second, equally efficient water pump. To control the pressure inside the apparatus, a screw clamp is placed between each Büchner flask and each pump (Note
5). With these clamps completely closed both pumps are turned on fully. The pressure inside the apparatus is now gradually reduced by opening the clamps at such a rate that no excessive frothing occurs. When both clamps are fully open, the water bath is heated slowly until the water in the reaction flask begins to boil. The bath is kept at this temperature until there is no more water left in the flask (Note
6). Then, with both clamps fully opened, the temperature of the water bath is raised to 100° during 15–20 minutes and kept at this temperature for 2 hours. After this time the catalyst is allowed to cool to 50–60°; it is now ready for use.