With the metal chlorides

Oiganometallic usage is shown in the piepaiation of titanium- oi vanadium-containing catalysts foi the polymerisation of styrene or butadiene by the reaction of dimethyl sulfate with the metal chloride (145). Free-radical activity is proposed for the quaternary product from dimethylaruline and dimethyl sulfate and for the product from l,l,4,4-tetramethyl-2-tetra2ene and dimethyl sulfate (146,147). 

The 1 1 complex with titanium chloride or the 1 2 complex with beryllium chloride may explode violently. Careful pyrolysis of these gives mixtures of disulfur dinitride and its 1 1 complexes with the metal chlorides, which may also explode, so screening is essential. 

Reactions with Metal Salts. Interactions of asphaltenes with the metal chlorides yield products containing organically bound chlorine, but the analytical data indicate dehydrogenation processes occurring simultaneously (12). There is, of course, no clear way by which the extent of the dehydrogenation can be estimated, but it may be a dehydro-... 

Ammonium thiomolybdate, (NH4)2MoS4, was reacted with the metal chloride (AX ) to obtain the precursor compound. 

Chlorination of Pt/HL at 400°C for 4 h leads to PtCl this was confirmed by the H2/Pt ratio from quantitative TPR results and by XPS (209). In the chlorination of large Pt or Pd aggregates in proton-rich zeolites, no interaction of protons with the metal chlorides is apparent below 350°C, but above 400°C HCl has been detected, indicating the occurrence of ion exchange and the reaction given by Eq. (16). 

The possibility of suspended transformation or the non-formation of the new phases must also be granted in the case where the vapour pressure is raised above that corresponding to the system hydrate— anhydrous salt (or lower hydrate)— vapour in this case the formation of the higher hydrate becomes a possibility, but not a certainty. Although there is no example of this known in the case of hydrated salts, the suspension of the transformation has been observed in the case of the compounds of ammonia with the metal chlorides (p. 76). Horstmann, for example, found that the pressure of ammonia in... 

Prior to film deposition, a temperature greater than = 550°C must be maintained during the mixing of hydrogen with the metal chloride gas stream to preclude snowing (parasitic prereaction) of NbCb [53]. 

Another interesting piece of work is concerned with metal fcis(dithiolene) complexes substituted peripherally with four or eight aliphatic chains ((70) R = OCJ32 +i> R = H R = R = OC H2/,+i). Structurally similar to the metal /3-diketonate complexes discussed above, it was expected that such complexes would exhibit columnar mesophases on the basis of their disk-like shape. Furthermore, combined with their vr-acceptor properties, such discogens could find potential applications as low-dimensional conductors. The complexes were synthesized in a one-pot procedure the appropriately substituted benzoin or benzil (a-diketone derivative) was treated with P4S10, and complexation was carried out in situ with the metal chloride salt. 

Most metal chlorides undergo only partial metathetical halide/alkoxide exchange upon reaction with alcohols or no reaction at all even at elevated temperatures. The metal alkoxide chlorides thus obtained, MClx(OR), have not been used in sol-gel processing (see, however. Section 7.10.3.3.2). In order to achieve the preparation of homoleptic metal alkoxides from metal chlorides basic conditions are essential in order to trap the liberated HCl. This can be achieved by reaction of metal chlorides with alcohols in the presence of a base such as ammonia or, less often, trialkylamines or pyridine (Equation (11a)). The base also increases the equilibrium concentration of alkoxide ions, which are a more powerful nucleophile for reaction with the metal chloride than the parent alcohol. For this reason the use of alkali alkoxides (M OR), mostly lithium, sodium, or potassium alkoxides, proves to be more successful (Equation (11b)). The use of LiOR has advantages for the preparation of insoluble metal methoxides because LiCl is soluble in methanol and is thus easily separated from insoluble metal alkoxides. 

Heat stabilizers belong to one of the two major classes primary heat stabilizers and secondary heat stabilizers. Primary heat stabilizers function both by retarding the dehydrochlorination process and by reacting with the liberated HQ to delay progress degradation. Secondary heat stabilizers or costabilizers are used to scavenge Uberated HCl from the PVC resin or to react with the metallic chloride by products of the primary mixed metal stabilizers. 

The nature of the alcohol has a significant influence on the preparation of alkoxides by the reaction involving metal chlorides and alcohols. For the lower straight chain alcohols such as methanol and ethanol, the alcohol undCTgoes a relatively straightforward reaction with the metal chloride and the base. However, for other alcohols, side reactions may assume a dominant role so that the yield of the alkoxide product is usually low. 

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