Alcohol, solvation

Anhydrous lanthanum and praseodymium trichlorides have been prepared from the hydrates by transforming them into alcohol solvates and breaking them down at 150-180°C in a vacuum 131). 

The nature of these products is unknown, but they may be mixed oxidation state UV/UVI species. Dioxouranium(VI) alkoxides, U02(0R)2, and some alcohol solvates are also known, (c) Aryloxides. The only aryloxides known are the dioxouranium(VI) compounds... 

On the other hand, numerous observations favour the opinion that the solvent enters into a chemical combination with nitrocellulose to form solvates. Some of those solvates are stable only at low temperatures. For instance, cellulose dinitrate does not dissolve in methyl alcohol at room temperature, though on cooling it does so. The cellulose nitric ester precipitates again when the solution is heated. Similar behaviour is observed with ethyl alcohol a lower temperature causes nitrocellulose to swell or even to dissolve more readily. The solvent seems likely to be bound to free hydroxyl radicals (Highfield [36]). The hypothesis explains why nitrocellulose is soluble in a mixture of ether and alcohol, though neither of these solvents, when used separately, is capable of dissolving it. It is assumed that first an alcohol solvate of nitrocellulose is formed which then dissolves in the ether. 

It was quite unexpectedly found that the amorphous samples of zirconium and hafnium alkoxides M(OR)4 contain several types of oxocomplexes, particularly, M3O(OR)i0 and M40(0R)14 [1612], The trinuclear Zr3([l3-0)()i3-OBu XOBu ), was isolated in a crystalline form and turned out to be a structural analog of the known isopropoxide clusters of Th, Mo, and U(IV) -MjOCOPr ),) [1520] (see also Sections 4.3 and 12.12). The inclusion of the solvent molecules inside the cavities of the structures and formation of alcohol solvates in many cases leads to microanalysis data that does not deviate much from those calculated for M(OR)n. 

The desolvation of alcohol solvates is to some extent always accompanied by the formation ofoxoligands, — for example,... 

The majority of Th(OR)4 have been isolated in the crystalline form only as pyridine solvates and Th(OBu )4 — as alcohol solvate (with 2 1 composition), the yields of complexes being rather far from quantitative [387]. This fact in combination with the observed molecular complexities (3-4) for unsolvated Th(OR)4 (R = Pf, Bu, C5H , C5H , CjH, ) — amorphous solids or viscous liquids—permits to suppose (in analogy with Zr(OR)4 and Hf(OR)4 , see Section 12.12) the existence in their samples oftri- and tetranuclear oxocom-plexes — MjO(OR)10 and M40(0R),4 — to be supposed. Crystalline Th3O(OBu )i0 has in fact been isolated on the hydrolysis of [Th(OBul)4Py2] [387] (Table 12.14). 

L-valyl-L-phenylalanine-2-propanol (1/1) and L-leucyl-L-phenylalanine-2-propanol (1/1) (P-form), Acta Cryst. C55, 2171-2177 d) Gorbitz, C. H. and Torgersen, E. (1999) Symmetry, pseudosymmetry and packing disorder in the alcohol solvates of L-leucyl-L-valine Acta Cryst. B55, 104-113 e) Mitra, S. N., Govindasamy, L. and Subramanian, E. (1996) L-Leucyl-L-alanine dimethyl sulfoxide solvate, Acta Cryst. C52, 2871-2873. 

One can assume that as the hydrate has already interacted intimately with water (the solvent), then the energy released for crystal break-up, on interaction of the hydrate with solvent, is less than for the anhydrous material. The nonaqueous solvates, on the other hand, tend to be more soluble in water than the nonsolvates. The n-amyl alcohol solvate of fludrocortisone acetate is at least five times as soluble as the parent compound, while the ethyl acetate solvate is twice as soluble. 

Intensely yellow leaflets from alcohol, solvated needles from chloroform, dec about 189. Practically inso] in water sol in alcohol, benzene, acetone, chloroform, ethyl acetate, dil acids slightly so] in ether. The ale soln undergoes partial decompn, indicated by a ted color, hence shonld be protected from light. Dipole moment in benzene 7,2. Solubility of some Nitron salts in 0,0lJV HCI Nitrate 0.0099%, perchlorate 0.008%, iodide 0.0] 7%, thiocyanate 0.04%, chromate 0.06%, chlorate 0.12%, nitrite 0.19%, bromide 0.61%. 

There have been many previous studies on zirconium compounds of the so-called fatty acids, which upon analysis are usually found to be oxy species. For example, the reaction of excess steric or palmitic acids with the isopropyl alcohol solvate of tetraisopropoxide zirconium (280, 281) in benzene at reflux temperatures gives final products which are consistent with the composition [(RC00)3Zr]20. Actually this reaction can be carried out so as to isolate the mono- and disubstituted alkoxides, Zr(RCOO)(OPr )3andZr(RCOO)2(OPr )2. Treatment of the disubstituted product with additional fatty acid in benzene gives products for which... 

The spectra were obtained at the most positive potential achievable in which the 3500 cm bands are at their maximum intensity. The bands at around 3650 cm arise from the free interfacial water. The frequency of this band decreases with an increase of the alcohol chain length in the solvent, since the alcohols solvate... 

Suggest an explanation for this effect of DMF on the basis of Lewis acid—base considerations. (Hint. Although water or an alcohol solvates both cations and anions, DMF is only effective in solvating cations.)... 

Recent crystal structure studies have shown that the interaction of basic hydroxides with aliphatic alcohols does not lead to metal alkoxides, but to alcohol solvates of the hydroxides. For example, the reaction of Ba(OH)2 with MeOH was found to provide Ba(OH)2(MeOH)2-MeOH (Turova, priv.commim.). 

It should be mentioned that the reaction of metal chlorides with alcohols could not be applied for the synthesis of metal alkoxides—precursors of oxide materials. Its products are usually quite complex mixtures of alkoxide chlorides and alcohol solvates of metal oxochlorides (Turova, 2002 Turevskaya, 1989). 

Formation of alcoholates—solvate complexes with functional alcohols can be considered as a variety of this synthetic approach. Metal j6-diketonates or carboxylates are reacted with amino- or alkoxy-alcohols in stoichiometric amounts in organic solvents (both nonpolar such as toluene or hexane or polar, such as methanol or ethanol can be applied (Williams, 2001 Seisenbaeva, in press) ... 

The solvent effect on intensities of hypersensitive transitions of R(C104)3 (R=Nd, Ho, Er) has been investigated by Legendziewicz et al. (1982). The molar refiactivities and oscillator strengths of hypersensitive bands are reported for water, alcohols, DMSO, DMF and diethylformamide. Intensities of the f-f bands and the nephelauxetic effect of the alcoholic solvates of the heavy-lanthanide chlorides with Ho(III) and Er(III) have also been reported (Keller et al. 1982). The intensity T2 parameter increases as follows ... 

It is to be noted that alkoxides of more electropositive metals - alkaline, alkaline earth, rare earth (RE), and Zr(IV), Hf(IV), and Sn(IV) - often form quite stable complexes with protic ligands, which are also Lewis bases (alcohok, amines). Their formation is supported by both complexation of the metal atom with this additional Lewis base function, which is apparently weaker than the alkoxide one, and formation of the hydrogen bonds with active hydrogen atoms of the additional ligands [61]. No stable complexes are formed with stronger but aprotic nucleophiles such as trialkylamines, R3N [62]. Very often, the alcohol solvates have a bit lower solubility, but are easily purified by recrystallization, which makes them attractive as commercial products. When the pure alkoxides are highly... 

Ethers were shown to form adducts with silicon compounds (e.g., 8,9 and 10), but literature reports on crystallographic evidence are limited to few examples [77-80]. In the same manner, alcohols and water should be capable of forming related adducts. Surprisingly, no example of an alcohol solvate can be found in the CSD [81], but adduct formation with alcohols has already been reported [82]. Water, however, has already been demonstrated by X-ray crystallography to act as a ligand in hypercoordinated Si complexes (e.g., 11 and 12) [82-85]. 

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