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Alkyl-oxygen cleavage of ester

Diamines from cblorocarbonic acid esters Alkyl-oxygen cleavage of esters... [Pg.408]

Therefore, transesterification reactions frequently fail when R is tertiary, since this type of substrate most often reacts by alkyl-oxygen cleavage. In such cases, the reaction is of the Williamson type with OCOR as the leaving group (see 10-14). With enol esters, the free alcohol is the enol of a ketone, so such esters easily... [Pg.487]

A second type of anomalous cryoscopic behaviour is exhibited by f-butyl esters ". The benzoate and acetate both give varying / -values between 3 and 4, and by extrapolating the value for f-butyl benzoate to zero time Kuhn1" obtained a value close to 3.0. This he interpreted as evidence for alkyl-oxygen cleavage, and the formation of the f-butyl cation, viz-... [Pg.64]

The reactions of protonated carboxylic esters in the absence of significant amounts of water have been discussed above. Two types of cleavage are possible. Alkyl-oxygen cleavage is a very fast reaction for the conjugate acids of tertiary alcohols... [Pg.74]

The final increase in the rate of hydrolysis of the esters of primary aliphatic alcohols, in 85-100% H2SO, is presumably due to acyl-oxygen cleavage, since methyl acetate reacts faster than the ethyl ester, which would not be the case for alkyl-oxygen cleavage. So also may be the rapid hydrolysis of aryl acetates at moderate acidity, since aryl-oxygen cleavage is not expected to be so rapid a reaction. [Pg.75]

This suggests that the hydrolysis of the ethyl ester involves the Aac1 mechanism, but that protonated isopropyl benzoate cleaves by alkyl-oxygen cleavage. A change in mechanism at this point would explain the order of reactivity towards hydrolysis of the various alkyl benzoates, observed by Kuhn18. [Pg.85]

Since the great majority of studies of ester hydrolysis involving the AAi 1 mechanism have been with tertiary alkyl esters, strongly acidic media have not been necessary indeed some esters undergo alkyl-oxygen cleavage even in the absence of strong acid (see p. 146). [Pg.87]

Another well-established class of ester reactions which involve alkyl-oxygen cleavage belongs to the large category of SN2 reactions. [Pg.147]

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esters of methanesulfomc acid, p-toluenesulfonic acid, and especially trifluoromethane-sulfonic acid (triflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... [Pg.211]


See other pages where Alkyl-oxygen cleavage of ester is mentioned: [Pg.68]    [Pg.87]    [Pg.110]    [Pg.68]    [Pg.87]    [Pg.110]    [Pg.7]    [Pg.69]    [Pg.75]    [Pg.86]    [Pg.97]    [Pg.102]    [Pg.189]    [Pg.8]    [Pg.476]    [Pg.534]    [Pg.473]    [Pg.259]    [Pg.14]    [Pg.241]    [Pg.39]    [Pg.109]    [Pg.151]    [Pg.582]    [Pg.335]    [Pg.381]    [Pg.338]    [Pg.7]    [Pg.76]    [Pg.84]    [Pg.87]    [Pg.89]    [Pg.92]    [Pg.94]    [Pg.96]    [Pg.98]    [Pg.100]    [Pg.101]    [Pg.137]    [Pg.148]    [Pg.67]    [Pg.444]    [Pg.187]   
See also in sourсe #XX -- [ Pg.21 , Pg.480 ]

See also in sourсe #XX -- [ Pg.21 , Pg.480 ]




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Alkyl esters

Alkylation of esters

Alkylation oxygen

Alkylative cleavage

Cleavage esters

Cleavage of esters

Esters alkylation

Oxygen cleavage

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