Acetals table

Nishioka and Fujita 68 78) have, independently of Van Etten et al.71), determined and analyzed the rate constants, k2, for the cyclodextrin-catalyzed cleavage of m-and p-substituted phenyl acetates (Table 6). They have derived Eqs. 37 to 40 ... 

The catalytic alcohol racemization with diruthenium catalyst 1 is based on the reversible transfer hydrogenation mechanism. Meanwhile, the problem of ketone formation in the DKR of secondary alcohols with 1 was identified due to the liberation of molecular hydrogen. Then, we envisioned a novel asymmetric reductive acetylation of ketones to circumvent the problem of ketone formation (Scheme 6). A key factor of this process was the selection of hydrogen donors compatible with the DKR conditions. 2,6-Dimethyl-4-heptanol, which cannot be acylated by lipases, was chosen as a proper hydrogen donor. Asymmetric reductive acetylation of ketones was also possible under 1 atm hydrogen in ethyl acetate, which acted as acyl donor and solvent. Ethanol formation from ethyl acetate did not cause critical problem, and various ketones were successfully transformed into the corresponding chiral acetates (Table 17). However, reaction time (96 h) was unsatisfactory. 

Reactivity of a number of solid acid catalysts that include zeolites, resin, nafion and HP As was determined for the direct reaction of ethylene with acetic acid to produce ethyl acetate (Table 1). It was established that the Keggin HSiW supported on silica is very active for the vapom phase reaction of acetic acid with ethylene at about 180°C, 145 psig with a high molar ratio of ethylene to... 

Much of the available published data on the aqueous solubility of disperse dyes was accumulated during the 1960s in the course of studies of the mechanism of dyeing cellulose acetate with disperse dyes. Most of the dyes examined were low-energy types for dyeing acetate (Table 3.5). Particular attention was given to monoazo dyes derived from aniline or... 

There is a roughly inverse relationship for a series of structurally related dyes between the time of half-dyeing and the saturation solubility in an appropriate substrate, as illustrated for several 4-alkylamino derivatives of 1-anilinoanthraquinone on cellulose acetate (Table 3.17). It is interesting that methylamino and 2-hydroxyethylamino substituents confer good solubility in this substrate, but ethylamino groups are even less effective than isobutylamino groups in this respect [114]. 

The values of AH for the thallium (III) halide systems becomes less exothermic as complex formation proceeds. There are no steps with about the same value of AH , in marked contrast to e.g. Hg2+ and Pd2+. The trend of AH is in fact opposite to that found for several t)q)ical hard-hard interactions, e.g. iron (III) fluoride, lanthanum sulphate and yttrium acetate (Table 1). An even more striking feature of the thallium (III) halides is that AS°n is approximately constant for all steps. This is indeed different not only from ions such as In +, Cd2+ and Zn +, where reversals of the decreasing trend of AS°n occur for certain steps, but also from Hg2+ and Pd + where the higher steps have a much lower value of ASn than the earlier ones. 

Further investigation with various silyl ketene acetals is summarized in Table 6. Silyl ketene acetals derived from various esters were reacted with /V-benzyloxy-carbonylamino sulfones 1 in the presence of 0.5-1 mol% Bi(0Tf)3-4H20. The corresponding (3-amino esters 24 were obtained in moderate to good yields (Table 6). Silyl enolates derived from esters as well as thioesters reacted smoothly to give the adducts. The /V - be n z v I o x v c ar bo n v I a m i n o sulfone derived from n-butvraldehyde lp led to moderate yields of (3-amino esters when reacted with (thio)acetate-derived silyl ketene acetals (Table 6, entries 1 and 2). A very good yield was obtained when the same sulfone was subjected to a tetrasubstituted silyl ketene acetal (Table 6, entry 3). The latter afforded moderate to good yields of (3-amino esters 24 with phenylacetaldehyde, / -tolu aldehyde, and o-tolualdehyde-derived sulfones (Table 6, entries 4-6). 

The second effect could be observed by comparison of the hydrolysis rates of primary and secondary acetates (Table 6). 

F-Teda BF4 (6) is very effective for the fluorination of a wide variety of organic substrates steroidal enol acetates (Table 7)92 and silyl enol ethers, certain carbanions, mildly activated aromatic compounds, and sulfides bearing oc-H atoms.73,75,76,77,84,88 90 The products are obtained with good yields and regioselectivity under very mild reaction conditions (Table 8). 

The cyanato- and, especially, the thiocyanato-boranes form equally stable complexes with amines, nitriles and ethyl acetate (Table 6). The Lewis acidity of these pseudohalogenoboranes and halogenoboranes, with respect to pyridine and ethyl acetate, follows the order Cl >NCS > NCO > F.79... 

The solvent acid also affects the oxidation rate since the rate with cobalt acetate (Table II) is reduced in propionic or butyric acids in contrast to the increase in the hydroperoxide decomposition rate. 

ISOAMYL ACETATE (Table VIII) Lubricating oils Ethylene glycol... 

Nucleophiles other than hydride can be added to support-bound imines to yield amines. These include C,H-acidic compounds, alkynes, electron-rich heterocycles, organometallic compounds, boronic acids, and ketene acetals (Table 10.9). When basic reaction conditions are used, stoichiometric amounts of the imine must be prepared on the support (Entries 1-3, Table 10.9). Alternatively, if the carbon nucleophile is stable under acidic conditions, imines or iminium salts might be generated in situ, as, for instance, in the Mannich reaction. Few examples have been reported of Mannich reactions on insoluble supports, and most of these have been based on alkynes as C-nucleophiles. 

Other solid-phase preparations of carbonyl compounds include the hydrolysis of acetals (Table 12.4), inter- [52] and intramolecular Pauson-Khand reactions, the isomerization of allyl alcohols, and the a-alkylation and a-arylation of other ketones. Tietze reported the generation of acetoacetyl dianions on cross-linked polystyrene and their selective alkylation at C-4 (Entry 6, Table 12.4). The use of weaker bases resulted in single or twofold alkylation at C-2 [53]. 

Table V contains a list of the absolute rates and relative rates of migration for various carbohydrates in methanolic solutions of potassium acetate and sodium acetate. Table IV shows the effect of different salts on the absolute rates and relative rates of D-xylose and D-glucose in methanol. The ability...

Surprisingly selective appears to be the oxidation of perfluorophenol for a brief period with concentrated nitric acid to give perfluoro-l,4-benzoquinone (fluoranil, 9).171 When the substrate is added too slowly the quinoid ether is partly formed,171 which in turn is easily prepared by lead(IV) acetate (Table 10).172... 

Exercise 29-17 Polyvinyl alcohol prepared by hydrolysis of polyethenyl ethanoate (polyvinyl acetate Table 29-1) does not react with measurable amounts of periodic acid or lead tetraethanoate (Sections 16-9A and 20-4A). However, periodic acid or lead tetraethanoate treatment of the polymer does decrease the number-average molecular weight, for a typical sample from 25,000 to 5000. Explain what these results mean in terms of the polymerstructures and the mechanism of the polymerization. 

Tn comparison to conventional extraction with ethyl acetate, Table HI for parameters... 

Di(l-methylbenzimidazol-2-yl)furan [ 4751-43-3] [81], which has the ability to form salts, was one of the first cationic benzimidazole brighteners. More recently, cationic benzimidazoles have been developed as brilliant, chlorine-fast, lightfast brighteners for polyacrylonitrile and cellulose acetate (Table 7.7). They are marketed in the form of cold- and heat-resistant concentrated aqueous solutions with long shelf lives. 

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