The Olation Reaction

Dynamic and isothermal thermogravimetric measurements [1284] for the olation reactions... 

A), strong, and centered hydrogen bonds.846 Heating of solid compounds (169) at 150°C leads to the formation of the dihydroxo-bridged dimers (170) (olation reaction Scheme 28).846 Stereoselectivity of the olation reactions for the [Cr2(chxn)4(/x-H307)2]41 complexes (chxn = (15,25)- or (15,25)-l,2-/nmv-cyclohexanediamine) has been discussed.847... 

Fig. 11. The olation reaction. The solid lined squares indicate the original tetrameric units, and the dashed lines denote new ol bridges...

The olation reaction between aquo-hydroxo complexes, or between aquo-hydroxo and aquo complexes, may be schematically written as... 

Oxolation may occur over a wide range of pH. The reaction rate will be at a minimum when the reactants carry no charge (neutral oxolation). This is not the case for the olation reaction, which involves aquo-hydroxo forms for which condensation rates are limited only by the lability of the water molecule. 

Alkoxy)alkynylcarbene complexes have been shown to react with nitrones to give dihydroisoxazole derivatives [47]. Masked 1,3-dipoles such as 1,3-thia-zolium-4-olates also react with alkynylcarbene complexes to yield thiophene derivatives. The initial cycloadducts formed in this reaction are not isolated and they evolve by elimination of isocyanate to give the final products [48]. The analogous reaction with munchnones or sydnones as synthetic equivalents of... 

The hydrolysis reaction is very slow at ambient temperatures and is accelerated by boiling chromium salt solutions (5). The hydrolysis reaction is characterized by the transformation of the deep blue colored CrtHgOJg to green colored hydrolyzed olates. Another indication is tnatan aged or boiled Cr(III) salt solution has a higher neutralization equivalent than a fresh one due to the hydrolytically produced protons. One way to establish hydrolytic equilibria quickly is to add appropriate equivalents of bases such as NaOH to Cr(III) salt solutions. 

Gelation time of a 2000 ppm Flocon 2% NaCl solution with 90 ppm Cr(III) according to Equation 5 was 2 weeks (Table II), which is in the range of the Cr colloid gelation discussed earlier. Based on the earlier discussion, the gelation reaction of redox generated Cr(III) can also be accounted for with the olation mechanism. However it is... 

The reaction of Cr(0H) and H+ is the reverse of the hydrolysis of CrCHgOJg (Equation 1). Therefore by adjusting the acidity of the redox reaction (Equation 8), Cr olates of all oligomerizations can be prepared. 

The condensation reactions occur only through the mediation of sylanol groups generated by hydrolysis. There are two main opportunities. The condensation can be carried out by oxolation or olation mechanisms. The oxolation occurs with the participation of two sylonol groups. In the course of the reaction a hydroxo ligand is exchanged for an oxo one [8] ... 

The result is a dimer in which the two silicon atoms are linked by the Si—O—Si siloxane bond. The olation is realized through involvement of both sylanol and alkoxy groups. It can be represented by the following general reaction ... 

The olation leads also to the formation of a dimer with siloxane bond. If the other alkoxy groups in its molecule have been also substituted to hydroxyls, the dimer keeps on going further condensation reactions. This results in the formation of a polymeric chain that can be linear, branched or cyclic. As general, it includes all these segments. 

The mesoionic 1,2,3-triazolium-4-olates 361a,b and l,2,3-triazolium-4-thiolate 361c did not react with benzocyclopropene (113), and the attempted reaction between l,3-diazolium-4-olate 362 and benzocyclobutadiene failed (114). In contrast to these negative results, Ichinari et al. (249) found that the isomeric l,3-diazolium-4-olates (l,3-imidazolium-4-olates) 363 and 364 react with DMAD to form pyridones and pyrroles, respectively. 

The chemical reactions of the cinnolinium-4-olates (233) are conveniently illustrated by considering specific reactions of the 2-methyl derivative (243) (Scheme 10). Compound 243 readily forms salts Ethanolic hydrogen chloride gives 2-methyl-4-hydroxycinnolinium chloride (239) and tri-ethyloxonium tetrafluoroborate gives 2-methyl-4-ethoxycinnolinium tetra-... 

Hydroxycinnoline (252) slowly dissolves in ethereal diazomethane producing a brilliant emerald green colour which changes to deep blue. Comparison with the analogous reaction of 8-hydroxyquinoline (Section III,B,5) has led to the suggestion that this blue product, mp 120°C, is l-methylcinnolinium-8-olate (251 R = Me). 

The l,2,4-triazolo[l,5,-a]pyrimidinium-2-olates (23) were prepared by the sequential reaction of 2-methylaminopyrimidines (21) with phosgene to give 22 followed by Me3SiN3 [87JCS(CC)112] (Scheme 8). 

The formation of chloroimino ligands has been proposed solely on weak v(C=N) vibrations in the 1600-1750 cm-1 IR region. A repeat of the vanadium reaction by other workers (109) found the product of their reaction to be VC13(CNBu )3, so some caution should be applied to the formulation of the proposed vanadium dimer at least. Substitution reactions on these compounds with a series of mono- and bidentate tertiary phosphorus ligands and metathetical replacements with lithium quinolin-8-olate and sodium diethyl dithiocarbamate have given a range of neutral and cationic products (204, 483). 

The replacement of halogen atoms in halides by alkoxide or thiolate ions is normally viewed as an alkylation of the olate moiety. For the purposes of this review we will consider this synthetically useful functional group interconversion as a nucleophilic displacement reaction of the halide by which ether and sulfide moieties are introduced into organic compounds. 

Werner and Surber2 used this olation reaction to assign configurations to the salts. The lilac-colored potassium salt, which crystallizes as either the di-or trihydrate, was first prepared by Werner and Surber.2... 

The recognition of H302 bridges provided an explanation for why it was the only cis-hydroxoaqua species that could undergo the so-called olation reaction to give dihydroxo species, i.e.,... 

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