Sponge nickel

The azido mesylate is suspended in absolute ethanol and 80% hydrazine hydrate (3 ml/g of azido mesylate). A small amount (tip of spatula) of Raney nickel (W-2 grade or commercial 50% sponge nickel catalyst from W. R. 

Preliminary kinetic analysis revealed that the reactions mentioned for various sugars were close to first order with respect to the organic reactant, while the reaction order with respect to hydrogen varied between 0.5 and 2.2, being 0.7 for hydrogenation of lactose on sponge nickel and about 2 for fructose hydrogenation on CuO/ZnO. 

Some data fitting results are displayed in Figures 12.1 and 12.3. The general conclusion is that both models describe the behaviours of the main components, lactose and lactitol very well, both for sponge nickel and ruthenium catalysts. In this respect, no real model discrimination is possible. Both models also describe equally well the behaviour of lactobionic acid (D), including its concentration maximum when the reversible step is included (ks) (Figure 12.3). 

The most common and least expensive catalyst for producing primaiy amines from nitriles is sponge nickel. The generalized reaction, carried out in the presence of sponge nickel catalyst, is the following ... 

The reaction mass consists of two liquid phases and one solid phase no solvent is required. The major liquid phase is the crude amine product itself. The solid phase is promoted sponge nickel catalyst. Surrounding the catalyst is a second liquid phase consisting of concentrated caustic and water. Water and caustic are added continuously to make up for losses leaving in the crude product. The ratios of water, caustic, and catalyst in the reaction mass are controlled to produce high yields of product amine and very low catalyst usages. High catalyst concentrations are employed in the reaction mass to keep the concentration of unreacted nitriles very low the upper limit on the catalyst concentration is the point where the circulation rate is inhibited. 

Next, a series of runs was conducted to determine the effect of various alkali metal hydroxide additions along with the sponge nickel catalyst. The 50 wt. % sodium hydroxide and 50 wt. % potassium hydroxide caustic solution used in the initial test was replaced with an aqueous solution of the alkali metal hydroxide at the level indicated in Table 2. After the reaction number of cycles indicated in Table 2, a sample was removed for analysis. The conditions and results are shown in Table 2. The results reported in Table 2 show the level of 2° Amine in the product from the final cycle. The level of NPA in all of the mns was comparable to the level observed in the initial test. No significant levels of other impurities were detected. 

Deactivation of Sponge Nickel and Ru/C Catalysts in Lactose and Xylose... 

Catalyst deactivation during consecutive lactose and xylose hydrogenation batches over Mo promoted sponge nickel (Activated Metals) and Ru(5%)/C (Johnson Matthey) catalysts were studied. Deactivation over sponge nickel occurred faster than on Ru/C in both cases. Product selectivities were high (between 97 and 100%) over both catalysts. However, related to the amount of active metal on the catalyst, ruthenium had a substantially higher catalytic activity compared to nickel. 

Catalyst deactivation often plays a central role in manufacturing of various alimentary products. Sugar alcohols, such as xylitol, sorbitol and lactitol, are industrially most commonly prepared by catalytic hydrogenation of corresponding sugar aldehydes over sponge nickel and ruthenium on carbon catalysts (5-10). However, catalyst deactivation may be severe under non-optimized process conditions. 

Figure 1. A. Consecutive xylose hydrogenation batches over 2.5 wt-% sponge nickel and 1.5 wt-% Ru/C catalyst. B. Catalyst deactivation during consecutive lactose hydrogenation batches over 5 wt-% sponge nickel and 2 wt-% Ru/C catalyst.

Figure 2. A. Consecutive xylose hydrogenation batches over sponge nickel catalyst (XA=xylonic acid). B. Influence of lactobionic acid (LBA) on lactose hydrogenation rate.

A solution of 5.0 g (14.3 mmoles) 5-amino-N-methoxy-l-p-D-ribofuranosylimidazole-4-carboxamidine 3, 5 -cyclic phosphate in 200 ml H2 preheated to 60°C and containing approximately 5.0 g moist sponge nickel catalyst, was shaken with 2-3 atm. H2 at 60°C for 2 h. The filtered solution was evaporated to dryness to give 3.75 g of 5-amino-l-p-D-ribofuranosylimidazole-4-carboxamidine 3, 5 -cyclic phosphate (82%), (recrystallization from water). 

Nickel metal occurs as a lustrous, white, hard, ferromagnetic, metallic solid. Nickel is commonly used as a catalyst for hydrogenation reactions for food chemicals. Depending on the use, Nickel catalysts fall into two general categories Sponge Nickel Catalyst and Supported Nickel Catalyst. 

Sponge Nickel Catalyst is typically used in the manufacture of amines and polyols. It is prepared by chemically treating a Nickel-aluminum amalgam with sodium hydroxide to remove... 

Sponge Nickel Catalyst Dissolve approximately 100 mg of sample in about 2 mL of hydrochloric acid, and dilute to about 20 mL with water. Place 5 mL of this solution into a test tube, add a few drops of bromine water, and make it slightly alkaline with ammonium hydroxide. Add 2 to 3 mL of a 1% solution of dimethylglyoxime in alcohol. An intense red color or precipitate forms. 

Sponge Nickel Catalyst Not less than 83.0% of Ni, calculated on the dried basis. 

Caution Sponge Nickel is pyrophoric when dried. Handle with extreme care. 

Procedure Determine as directed under Procedure for Sponge Nickel Catalyst, beginning with Add 2 g of tartaric acid.. .. ... 

Sponge Nickel Catalyst Store under liquids such as water, alcohol, or methylcyclohexane in a cool, dry place. 

The reduction of nitriles is of wide scope and has been applied to many nitriles. When catalytic hydrogenation is used, secondary amines, (RCH2)2NH, are often side products.These can be avoided by adding a compound, such as acetic anhydride, which removes the primary amine as soon as it is formed, or by the use of excess ammonia to drive the equilibria backward. Sponge nickel or nickel on silica gel have been used for the catalytic hydrogenation of aryl nitriles to amines. 

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