Trihalides hydrolysis

Lower oxidation states are rather sparsely represented for Zr and Hf. Even for Ti they are readily oxidized to +4 but they are undoubtedly well defined and, whatever arguments may be advanced against applying the description to Sc, there is no doubt that Ti is a transition metal . In aqueous solution Ti can be prepared by reduction of Ti, either with Zn and dilute acid or electrolytically, and it exists in dilute acids as the violet, octahedral [Ti(H20)6] + ion (p. 970). Although this is subject to a certain amount of hydrolysis, normal salts such as halides and sulfates can be separated. Zr and are known mainly as the trihalides or their derivatives and have no aqueous chemistry since they reduce water. Table 21.2 (p. 960) gives the oxidation states and stereochemistries found in the complexes of Ti, Zr and Hf along with illustrative examples. (See also pp. 1281-2.)... 

The hydrolysis of 106 was studied in some detail and led to the isolation and structural characterization of a rare example of a titanoxane derivative with a planar Ti2(p-G)2 core 108 [111]. The formation of complex 108 can be contrasted with the hydrolysis reaction of the trihalides in the Cp and Cp series giving rise... 

Antimonyl chloride (sometimes called antimony oxychloride) is known as a "basic chloride." It is insoluble in water, but aqueous solutions of the trihalides can be made if enough HX is present to prevent hydrolysis. Adding water to reduce the concentration of acid causes the oxychloride to precipitate. 

From the standpoint of use, PC13 is the most important of the trihalides. In addition to hydrolysis, PC13 reacts with oxygen and sulfur to produce OPCl3 and SPC13, respectively. 

The reactivity of aryltellurium trihalides decreases on going from the chlorides to the iodides, the same trend occurring for hydrolysis. Aryltellurium trichlorides are very sensitive to water and moisture and are easily hydrolysed, the tribromides being more stable, while the triiodides are unaffected by cold water and can be prepared even by aqueous procedures. Diaryltellurium dihalides are stable in water, and ionic exchange reactions allow the conversion of dichlorides into dibromides and diiodides. 

Aryltellurium trihalides are sensitive to water and can be converted into products at different stages of hydrolysis. Oxohalides, aryltellurinic acids and aryltellurium anhydrides have been known for a long time, the oxohalides being the products of partial hydrolysis. 

A methyl ester was formed by methanolysis of a trihalide (Equation 32) <2007S225>. Decarboxylation of the /3-ketoacid resulting from hydrolysis has also been reported (Equation 33) <1980LA1917>. A carboxylic acid substituent was reduced to aldehyde with LAH (Equation 34) <1974J(P1)2092>. Thiazine nitrogen probably participates in this reaction. 

Alcoholysis of trihalides 0-6 Hydrolysis of ortho esters 0-20 Alcoholysis of acyl halides 0-21 Alcoholysis of anhydrides 0-22 Esterification of carboxylic acids 0-23 Transesterification 0-24 Alkylation of carboxylic acid salts 0-25 Cleavage of ethers with anhydrides 0-26 Alkylation of carboxylic acids with diazo compounds... 

Bismuth trihalides exhibit an increased tendency toward hydrolysis, usually forming bismuthyl compounds, also called bismuth oxyhalides,... 

Aryltellurinic acid anhydrides 9 are prepared by alkaline hydrolysis of aryltellurium trihalides 5, followed by acidification.84-86 The anhydrides 9 precipitate as white solids in high yields (Scheme 15). 

Organo tellurium trihalides are the best known and most numerous compounds among the tellurinic acid derivatives. Most of the other derivatives are represented only by a few compounds, some of which have not been adequately characterized. Frequently, different products are claimed for similar reactions with identical starting materials. Much more work needs to be done with the various hydrolysis products of organo tellurium halides before this area of organic tellurium chemistry can be considered to be adequately explored. 

Aryl tellurium trihalides treated with water are converted to arenetellurinyl halides. The susceptibility to hydrolysis decreases from the trichlorides to the triiodides2,3. With basic aqueous solutions (sodium carbonate, sodium hydroxide) tellurinic acids or tellurinic acid anhydrides are formed2 5. 

Ammonium aryltetrachlorotellurates were also obtained in yields of 40% or less when diethylamine, trimethylsilyl(diethyl)amine, pyrrolidine, or A-(trimethylsilyl)pyrrolidine were reacted with aryl tellurium trihalides in benzene solution1. The initial products in these reactions are aryl amino tellurium dichlorides, which are then converted to the ammonium tetrachlorotellurates by hydrogen chloride. Hydrogen chloride is formed in the condensation of diethylamine with the aryl tellurium trichlorides, through hydrolysis of chlorotri-methylsilane, or through interaction of the aryl tellurium trichloride with benzene. 

Silsesquioxanes. At the same time as silanetriols were stabilized, another significant observation was made in the hydrolysis of silyl trihalides. Incompletely condensed silsesquioxanes, RySiyOgfOH (Chart 6) are formed along with other products during the hydrolysis of RSiCl3 (R =... 

Oxyfluorides are the most stable of the oxyhalides, and the stability decreases with increasing atomic weight of the halogen. Special methods are used in the preparation of oxyfluorides, while the other oxyhalides can be prepared by general reactions, such as the partial hydrolysis of the pentahalides, or the oxidation of the trihalides. The compounds fume in the air and readily undergo further hydrolysis giving hydrogen halides and oxyaeids of phosphorus. 

The general chemistry of Ac3 in both solid compounds and solution, where known, is very similar to that of lanthanum, as would be expected from the similarity in position in the Periodic Table and in radii (Ac3, 1.10 La3, 1.06 A) together with the noble gas structure of the ion. Thus actinium is a true member of Group 3, the only difference from lanthanum being in the expected increased basicity. The increased basic character is shown by the stronger absorption of the hydrated ion on cation-exchange resins, the poorer extraction of the ion from concentrated nitric acid solutions by tributyl phosphate, and the hydrolysis of the trihalides with water vapor at 1000°C to the oxohalides AcOX the lanthanum halides are hydrolyzed to oxide by water vapor at 1000°C. 

Heavier halogens such as chlorine and bromine provide their boron trihalides with better complexing ability than BF3, but their facile hydrolysis makes BF3 the more effective Lewis acid choice. 

The covalent trihalides of thallium(III) are less stable than the trihalides of the lighter metals of group 13. Aqueous solutions of these compounds are acidic because of their extensive hydrolysis. The compound TICI3 is an important starting material for the preparation of Tl organometallic compounds. 

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