Of titanium compounds

Data relating to changes of state of selected titanium compounds are Hsted in Table 1. Heats of formation, free energy of formation, and entropy of a number of titanium compounds at 298 and 1300 K are collected in Table 2. 

Table 1. Thermal Data for Changes of State of Titanium Compounds...

Manufacture. Titanium chloride is manufactured by the chlorination of titanium compounds (1,134—138). The feedstocks usually used are mineral or synthetic mtile, beneficiated ilmenite, and leucoxenes. Because these are all oxygen-containing, it is necessary to add carbon as well as coke from either coal or fuel oil during chlorination to act as a reducing agent. The reaction is normally carried out as a continuous process in a fluid-bed reactor (139). The bed consists of a mixture of the feedstock and coke. These are fluidized by a stream of chlorine iatroduced at the base (see Fluidization). The amount of heat generated in the chlorination process depends on the relative proportions of CO2 or CO that are formed (eqs. 1 and 2), and the mechanism that... 

The following discussion on health and safety aspects of titanium compounds is concerned only with the behavior of the titanium present in inorganic compounds and not with the effects of the compounds themselves. For example, titanium tetrachloride must be treated with care because of the effects of the hydrochloric acid and heat produced when it reacts with water, not because of the possible toxicity of titanium. Apart from very few exceptions, the inorganic compounds of titanium are generally regarded as having low toxicity. Because of the ubiquitous nature of the element and its compounds, average concentrations of titanium in blood have been determined at 130—160 Fg/L (182—184), with a typical value of 10 Fg/L in urine (185). 

Considerable attention is also being given to the anti-tumor activity of titanium compounds. 

Organic titanium compounds are useful as crosslinkers [1462]. Aqueous titanium compositions often consist of mixtures of titanium compounds. 

D. Chain Transfer Process Depending on the Amount of Titanium Compound. 32... 

The kinetics of the above reported chain transfer reactions seem to be also catalytically affected by the titanium compound present in the reaction system. In fact we have observed (Table III) that both the numbers of ethyl groups and aluminum atoms bound to the polymeric chains decrease with decreasing amount of titanium compound in the catalytic system. 

As described in the previous paragraph, we investigated the influence of increasing amounts of titanium compounds on the molecular weight, and other characteristics of the polymer. 

It follows from the above reported results that an agent whose concentration depends upon the amount of titanium compound introduced into the reagent system takes part directly or indirectly in a chain transfer process. 

The terms of the numerator indicate the rates of chain transfer and termination processes depending, respectively, on the concentration of the growing chains, on the partial pressure of olefin, on the concentration of alkylaluminum, and on the amount of titanium compounds. 

The amount of amorphous polymer, which is generally produced in small percentage (9-16%) contemporaneously with the non-atactic polymer, is independent of reaction time (see Table II). It is on the contrary closely connected with the nature of the catalytic system employed and changes, for instance, when the triethylaluminum is substituted by other metal alkyls (beryllium alkyls, propylaluminum, isobutylaluminum, etc.) 5,28). It also depends on the purity of the a-titanium trichloride, in particular increasing in the presence of other crystalline modifications of titanium trichloride [i.e. -TiCU (27)] and of titanium compounds obtained by reduction of titanium tetrachloride at low temperature with aluminum alkyls. 

Photolysis [KINETTCMEASUREMENTS] (Vol 14) maleic anhydnde [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) of molybdenum compounds [MOLYBDENUM AND COMPOUNDS] (Vol 16) of pesticides [SOIL CHEMISTRY OF PESTICIDES] (Vol 22) of silanes [SILICON COMPOUNDS - SILANES] (Vol 22) of titanium compounds [TITANIUM COMPOUNDS - ORGANIC] (V ol 24)... 

Silanediols -htanates of [TITANIUM COMPOUNDS - ORGANIC] (Vol24)... 

Mechanistic information is difficult to obtain when the catalytically active titanium centers are present in a dilute matrix of silica. Only few techniques can be applied, and the available information does not allow discrimination between possible mechanisms. Consequently, it is necessary in this discussion to rely on analogies with the known chemistry of titanium compounds. 

The polymeric nature of zirconium in aqueous systems is similar to that of titanium compounds. However, zirconium compounds tend to be significantly more stable towards hydrolytic polymerization. 

The oxidative alkylation of titanium compounds (Cp TiX Cp" = r] -C5MQs, X = Me, OMe, Cl, N=CH-f-Bu) by dimethylzinc and dimethylcadmium has been reported to afford diamagnetic see Diamagnetism) compounds of general formula Cp2TiMe(X) and metallic zinc and cadmium, respectively. ... 

Itin, V. I., Bratchikov, A. D., Merzhanov, A. G., and Maslov, V. M., Principles of self-propagating high-temperature synthesis of titanium compounds with elements of the iron group. Combust. Sci. Tech., 17,293 (1981b). 

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