Stabilization decomposition ratio

Figure 10. Stabilization to decomposition ratio for CnHon+. Slope at 0.004 torr C%H4 based on points outside the range of the graph.

Cyclopentadienyltitanium Compounds with Other Carbon Titanium Links. Cyclopentadienyltitanium trichloride and, particularly, CpgTiClg react with RLi or with RAl compounds to form one or more R—Ti bonds. As noted, the Cp groups stabilize the Ti—R bond considerably against thermal decomposition, although the sensitivity to air and moisture remains. Depending on the temperature, mole ratio, and stmcture of R, reduction of Ti(IV) may be a serious side reaction, which often has preparative value for Cp Ti(Ill) compounds (268,274,275). 

Replenishment should be done with caie. Massive additions can cause decomposition. Maximum stability of electroless baths is obtained when continuous replenishment is practiced. Colorimetric analy2ers are commonly used to control the addition of replenisher solutions in a set ratio based on the nickel or copper content of the bath. A number of machines are available that continuously analy2e plating baths and make additions based on each separately analy2ed component. 

An alternative approach to increase the oxidation rate is the use of alkaline solutions, because bases enhance the reactivity of L-sorbose and weaken the adsorption strength of 2-KLG. Unfortunately, the rate enhancement at higher pH is accompanied by a drop in selectivity due to the poor stability of 2-KLG in alkaline solutions. To circumvent this problem, we have modified the platinum catalysts by adsorbed tertiary amines and carried out the oxidation in neutral aqueous solution [57], This allowed to enhance the rate without increasing the pH of the bulk liquid, which leads to detrimental product decomposition. Small quantities of amines (molar ratio of amine sorbose = 1 1700, and amine Pts = 0.1) are sufficient for modification. Using amines of pKa a 10 for modification, resulted in a considerable rate enhancement (up to a factor of 4.6) with only a moderate loss of selectivity to 2-KLG. The rate enhancement caused by the adsorbed amines is mainly determined by their basicity (pKa). In contrast, the selectivity of the oxidation was found to depend strongly on the structure of the amine. 

On the alloy surface the reaction proceeded both via the anhydride and formate intermediates (117). As the copper concentration was increased, the formate species dominated the reaction, until at 63% copper the CO/COj ratio was less than 0.1. This change was due to the decrease in the amount of anhydride formed with increasing copper and the corresponding increase in formate. Since only the anhydride decomposition produced CO, the relative amount of anhydride formed could be determined as a function of surface composition. This relationship is shown in Fig. 21 the anhydride concentration fell as the fourth power of the nickel concentration, suggesting the requirement of four nickel atoms for its stabilization. This value agreed with the earlier determination for the saturation density of anhydride intermediates on Ni(llO) (99). 

Decomposition of this equilibrium mixture with catalytic amounts of CuOTf affords a mixture of all three possible biaryls. The formation of the unsymmetrical biaryl 2-Me2NCH2C6H4C6H4Me-4 can only be explained by the occurrence of aggregated copper species in which both the C6H4CH2NMe2-2 and the C( H4Me-4 groups are bound to the same copper core [77]. It was furthermore observed that the ratio of the formed biatyls is not statistical, which points to significant differences in the thermodynamic stabilities of the various mixed aggregates present in solution. 

Polymer-stabilized bimetallic nanoparticles containing both a light transition metal element and a precious metal element can also be prepared by a modified alcohol reduction method. For example, Cu/Pd bimetallic nanoparticles were successfully prepared with various Cu Pd ratios by refluxing a glycol solution of the hydroxides of Cu and Pd in the presence of PVP or by thermal decomposition of metal acetates. 

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