Kinetics decomposition, interference from

X-ray patterns of the products formed by the reaction between strontium carbonate and anatase, rutile, and nonstoichiometric rutile each showed SrTiOj to be the only phase present. X-ray patterns of partially reacted compacts revealed the presence of strontium titanate, strontium carbonate, and titania. The absence of strontium oxide indicates that the carbon dioxide evolution was associated with the reaction between SrCOj and Ti02 to form a product phase and not with the decomposition of SrCOj to SrO. The data of Wanmaker and Radielovic for the rate of dissociation of strontium carbonate indicates that interference from dissociation in measuring the kinetics of interaction between SrCOj and Ti02 is negligible below 900°C. Above this temperature a correction may be necessary for the dissociation of SrCOj. However the fact that the same kinetic model can be used to represent the data above and below this temperature suggests that the correction term is small. 

Because of the small concentration of the 2 1 complex the last term can be ignored. From the extreme rate values in the absence of zinc and with an excess of zinc, 2i and 22 are determined as 2.4 X 104 min.-1 and 1.57 min.-1 respectively. These values can be combined with the trend in the rate constants to give the stability constant of the reactive complex, presumably Zn(OR)(OAc), as 3 X 107. For the simple zinc complex in water the literature values of the stability constant for the 1 1 complex vary from 2.5 X 108 to 6.3 X 108. The diazo coupling reaction of the complex indicates the smaller effect of coordination vis a vis protonation since this reaction is very sensitive to such effects and does not proceed with phenols. Unfortunately the choice of cations for such a reaction is restricted since the cation should not interfere with the analytical methods used to obtain the kinetic data nor should it introduce additional reactions such as occur with transition metal cations which can catalyze the decomposition of the diazonium salt via a redox process. 

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