Alcoholysis-hydrolysis

Tetrachlorosilane was added to aqueous ethanol (the presence of water was accidental). There was no proper stirring during this operation, which led to the formation of two liquid layers of compounds that did not react. The very fast and exothermic reaction of the alcoholysis-hydrolysis of chlorosilane started violently and the large compoundion of hydrogen chloride caused the reactor to detonate. 

Biphasic systems have been effectively used in several enzyme-catalyzed reactions, including peptide and alkyl glycosides synthesis, esterification and transesterification, alcoholysis, hydrolysis, and enantiomeric resolution [2, 24, 60]. Although application of this particular bioconversion system has been used for final products, it is mostly used in the production of intermediate compounds, particularly optically active ones, that can be used as building blocks in the pharmaceutical and food sectors [61-64]. Updated reviews have addressed this matter [2, 4, 24, 60-63], and examples of some representative recent applications of this methodology are given in Table 8.1). 

Nesmeyanov et al. 201-211) have carried out a systematic study of cyclopentadienyl ligand substitution in bis- and mono-cyclopentadienyl derivatives of titanium, including alcoholysis, hydrolysis, and reaction with FeClj. 

It is possible to increase the hydroxyl number by developing an alcoholysis - hydrolysis reaction. 

Introduction.—Few reviews have appeared dealing with more or less general aspects of cyclophosphazene chemistry. The role of cyclophosphazenes as model compounds for reactions of their polymeric analogues has been discussed some fundamental subjects in the area of phosphorus-nitrogen chemistry such as aminolysis, alcoholysis, hydrolysis, and tautomerization phenomena have also been discussed. An extensive review has appeared dealing with reactions of phosphazenes with alkoxides and aryloxides. ... 

PVAl is obtained from PVAc by alcoholysis, hydrolysis or aminolysis [485] PVAl-PVAc with the degree of hydrolysis below 83% shows the LCST behaviour between 0 and 100°C Tcp decreases with increasing VAc content [124, 491-493]... 

Table 5. Gas yields obtained diethylzinc upon alcoholysis/hydrolysis of...

Fig. 41. Alcoholysis - hydrolysis apparatus for estimation of aluminium bound alkyl and hydride groups.

Table Al. Alcoholysis/Hydrolysis of Diethylaluminium Ethoxide and Di-n-Propylaluminium Isopropoxide... 

Phillip et al also compared their method with the alcoholysis-hydrolysis procedure described by Crompton and Reid and Crompton. Again good to excellent agreement is obtained as shown in Table 47,... 

As a class of compounds, nitriles have broad commercial utility that includes their use as solvents, feedstocks, pharmaceuticals, catalysts, and pesticides. The versatile reactivity of organonitnles arises both from the reactivity of the C=N bond, and from the abiHty of the cyano substituent to activate adjacent bonds, especially C—H bonds. Nitriles can be used to prepare amines, amides, amidines, carboxyHc acids and esters, aldehydes, ketones, large-ring cycHc ketones, imines, heterocycles, orthoesters, and other compounds. Some of the more common transformations involve hydrolysis or alcoholysis to produce amides, acids and esters, and hydrogenation to produce amines, which are intermediates for the production of polyurethanes and polyamides. An extensive review on hydrogenation of nitriles has been recendy pubHshed (10). 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

Acidic Cation-Exchange Resins. Brmnsted acid catalytic activity is responsible for the successful use of acidic cation-exchange resins, which are also soHd acids. Cation-exchange catalysts are used in esterification, acetal synthesis, ester alcoholysis, acetal alcoholysis, alcohol dehydration, ester hydrolysis, and sucrose inversion. The soHd acid type permits simplified procedures when high boiling and viscous compounds are involved because the catalyst can be separated from the products by simple filtration. Unsaturated acids and alcohols that can polymerise in the presence of proton acids can thus be esterified directiy and without polymerisation. 

CycHc esters show accelerated hydrolysis rates. Ethylene sulfate compared to dimethyl sulfate is twice as fast ia weak acid (first order) and 20 times as fast ia weak alkaH (second order) (50). Catechol sulfate [4074-55-9] is 2 x 10 times faster than diphenyl sulfate ia alkaline solution (52). Alcoholysis rates of several dialkyl sulfates at 35—85°C are also known (53). 

The acylates undergo facile hydrolysis or alcoholysis with loss of one or both Cp groups (335). 

Pyrimidine-5-carbonitrile, 4-amino-6-methyl-synthesis, 3, 114 Pyrimidinecarbonitriles alcoholysis, 3, 83 aminolysis, 3, 83 hydrolysis, 3, 83, 127 oxides... 

The most convenient laboratory method for the preparation of 2,4-dimethyl-5-carbethoxypyrrole is that given above. A cheaper method of obtaining large quantities consists in the partial hydrolysis of 2,4-dimethyl-3,5-dicarbethoxypyrrole with sulfuric acid, followed by decarboxylation. The ester has been obtained also by the alcoholysis of 5-trichloroaceto-2,4-dimethyl-pyrrole in the presence of sodium ethylate. The free acid has been obtained fronii-[2,4-dimethylpyrrole-5]-2,4-dimethylpyrrole-5-carboxylic acid and from 2,4-dimethylpyrrole-5-aldehyde. ... 

Either acid or base catalysis may be employed. Alkaline catalysts such as caustic soda or sodium methoxide give more rapid alcoholysis. With alkaline catalysts, increasing catalyst concentration, usually less than 1% in the case of sodium methoxide, will result in decreasing residual acetate content and this phenomenon is used as a method of controlling the degree of alcoholysis. Variations in reaction time provide only a secondary means of controlling the reaction. At 60°C the reaction may takes less than an hour but at 20°C complete hydrolysis may take up to 8 hours. 

Alcoholysis of 1 -chloro-2-acyl-1,1,2-trifluoroethane, available from trifluoro-ethylene, an acyl chloride, and aluminum chloride, leads to 1-fluoro- 1-acylacetates [/] (equation 1) It is surpnsing that the remaining carbon-tluorine bond resists hydrolysis. 

Innumerable derivatives have been prepared by the standard techniques of organic chemistry. The organosilanes tend to be much more reactive than their carbon analogues, particularly towards hydrolysis, ammonoly-sis. and alcoholysis. Further condensation to cyclic oligomers or linear polymers generally ensues, e.g. ... 

Modification of the Erlenmeyer reaction has been developed using imines of the carbonyl compounds, obtained with aniline," benzylamine or n-butylamine. Ivanova has also shown that an A-methylketimine is an effective reagent in the Erlenmeyer azlactone synthesis. Quantitative yield of 19 is generated by treatment of 3 equivalents of 2-phenyl-5(4ff)-oxazolone (2) (freshly prepared in benzene) with 1 equivalent of iV-methyl-diphenylmethanimine (18) in benzene. Products resulting from aminolysis (20), alkali-catalyzed hydrolysis (21), and alcoholysis (22) were also described. 

The mechanism of hydrolysis and alcoholysis has been described, and the greater reactivity of the 4-position over the 2-position is attributed to the greater stability of the transition complex (20) with respect to (21), hence its greater ease of formation. The hydrolysis... 

A variety of solvents have been used successfully. Extensive hydrolysis or alcoholysis may accompany reduction in aqueous or alcoholic solvent, attack presumably occurring on the intermediate vinyl ether (SS). 

The report from Sheldon and co-workers was the second publication demonstrating the potential use of enzymes in ionic liquids and the first one for lipases (Entry 13) [43]. They compared the reactivity of Candida antarctica lipase in ionic liquids such as [BMIM][PFg] and [BMIM][BF4] with that in conventional organic solvents. In all cases the reaction rates were similar for all of the reactions investigated alcoholysis, ammoniolysis, and per hydrolysis. 

In 1965, Breslow and Chipman discovered that zinc or nickel ion complexes of (E)-2-pyridinecarbaldehyde oxime (5) are remarkably active catalyst for the hydrolysis of 8-acetoxyquinoline 5-sulfonate l2). Some years later, Sigman and Jorgensen showed that the zinc ion complex of N-(2-hydroxyethyl)ethylenediamine (3) is very active in the transesterification from p-nitrophenyl picolinate (7)13). In the latter case, noteworthy is a change of the reaction mode at the aminolysis in the absence of zinc ion to the alcoholysis in the presence of zinc ion. Thus, the zinc ion in the complex greatly enhances the nucleophilic activity of the hydroxy group of 3. In search for more powerful complexes for the release of p-nitrophenol from 7, we examined the activities of the metal ion complexes of ligand 2-72 14,15). 

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