Acidic cleavage, of ethers

The problem with solvents is that in most cases they decompose under the reaction conditions used in the reductive carbonylation reaction. Solvent decomposition can occur in a variety of ways including (i) acid cleavage of ether linkages by HI and HCo(CO), (ii) well known hydrolysis and halogenation reactions. 

Q Suggest mechanisms for the displacement of the sulfonic acid group by hydroxide ion and the acid cleavage of ethers to produce phenols, and comment on the differences. 

In the case of the acid cleavage of ethers, which can be achieved with either concentrated hydriodic acid or hydrobromic acid, this proceeds by protonalion of the oxygen atom, followed by nucleophilic displacement of phenol as shown in Scheme 4.5. 

Hydiobiomic acid Cleavage of ethers 8. 1, 11/2 2, 31 4, 18 with simultaneous replacement of nitro groups by bromine 8. 5, 411 Cleavage of trityl ethers s. 2, 249 3,10 Hydroxycarboxylic acids from methoxynitriles s. 2, 236 HBr ROR -V ROH... 

Both HI and HBr can be used to cleave ethers. HCI is less efficient, and HF does not cause acidic cleavage of ethers. This reactivity is a result of the relative nucleophilicity of the halide ions. 

Cleavage of ethers with hydriodic acid. Aliphatic ethers suflFer fission when boiled with constant boiling point hydriodic acid ... 

When it does occur, the Bal2 mechanism is easy to detect, since it is the only one of the base-catalyzed mechanisms that requires inversion at R. However, in the last example given, the mechanism is evident from the nature of the product, since the ether could have been formed in no other way. The Aal2 mechanism has been reported in the acid cleavage of y-lactones. ° ... 

Arylalkanoic acid esters, 72 166 Arylaldehydes, microwave-accelerated transformation to nitriles, 76 580-581 Aryl alkyl ethers, acid cleavage of, 70 569 Arylalkylsulfones, 9 273 Arylamine dye intermediates, 9 272t... 

Although the conditions used to cleave the ether linkage are vigorous, we decided to attempt this reaction on the a -alkoxy N-nitrosamines. The cleavage of ethers with acetic anhydride in the presence of Lewis acids is well-known in the literature (12,13,14). Reaction of a -methoxy dimethylnitrosamine IV with Ac20 in the presence of BF3 etherate at 60° resulted in the cleavage not only of the C-0 bond but also the N-C bond (15,16). ... 

COOH stabilizes the ring towards acid cleavage of the ether bond.)... 

Hydrolysis of carboxylic esters 0-17 Transetherification 0-18 Payne rearrangement 0-23 Transesterification 0-55 Ammonolysis of carboxylic esters 0-68 Cleavage of ethers with concentrated acids... 

Alcoholysis of trihalides 0-6 Hydrolysis of ortho esters 0-20 Alcoholysis of acyl halides 0-21 Alcoholysis of anhydrides 0-22 Esterification of carboxylic acids 0-23 Transesterification 0-24 Alkylation of carboxylic acid salts 0-25 Cleavage of ethers with anhydrides 0-26 Alkylation of carboxylic acids with diazo compounds... 

Deegan, T. L. Gooding, 0. W. Baudart, S. Porco, J. A., Jr. Non-Acidic Cleavage of Wang-Derived Ethers from Solid Support Utilization of a Mixed-Bed Scavenger for DDQ, Tetrahedron Lett. 1997, 38, 4973. 

Dimethoxycinnamic acid is a good source of 6-hydroxycoumarin and the preparation illustrates the value of boron tribromide in the cleavage of ethers (69MI22401). 

A variety of organic reactions, including dehydration of alcohols, cleavage of ethers, many additions to olefins, a number of nucleophilic substitutions, and various rearrangements, are catalyzed by acids. Since the substrates in these... 

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