Replacement of halogen by oxygen

The technique for alkylating salts of carboxylic acids is simple The salt is heated with the halide, if necessary in a closed tube or an autoclave. The product is worked up by any suitable process. 

For sensitive or valuable carboxylic acids silver salts are usually used these are readily prepared and sparingly soluble, but lead or alkali salts react similarly. 

Briihl875 observed that alkali salts often do not react smoothly with alkyl halides, but that in such cases addition of a little methanol may be helpful. It is essential that the salt be finely divided lead or silver salts should be washed with water, alcohol, and ether after their preparation and then dried in a vacuum-desiccator heat should be avoided during drying. 

Iodides react most readily of the halides and are also to be recommended because of their relatively high boiling points. In many cases solvents or diluents are helpful, e.g., xylene, benzene, toluene, light petroleum, chloroform, ether, or acetone. 

According to Liebermann and Lindenbaum876 it is unnecessary to isolate the silver salt the mixture of acid and alkyl halide may be treated with silver oxide in a diluent. 

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Ether formation by replacement of halogen by oxygen alkylation by halogen compounds... 

M ercuryj nitrogen d i oxi d e I oxygen Preferential replacement of halogen by oxygen Carboxylic acid fluorides from polyhalides... 

Substitution of halogen by oxygen has been used in the synthesis of nucleosides. Photolysis of 2-iodoadenosine in water provides isoguanosine725. 2 -Deoxyisoguanosine and some base-modified analogues were prepared via photochemical replacement of chlorine or bromine by water726. 

Hydroxide Ions. The photolysis of propanil, 4-CPA, and other chlorinated aromatic pesticides in water also can generate phenols through the replacement of halogen by hydroxyl groups (39, 41). Oxygen does not seem to have an important part in this reaction, if it is involved at all, and observation that the replacement proceeds upon irradiation... 

Pyridine/phosphorus pentasulfide Replacement of halogen and oxygen by sulfhydryl... 

Reductive removal of halogen substituents has been of value in the synthesis of pyrimidines and purines since the time of Fisher (1899). Natural purines were de-oxygenated in a sequence of reactions involving the replacement of hydroxyl by chlorine through the reaction with phosphorus pentachloride and the reduction using zinc dust and water [152], 2-Chloropurines 45 are not reduced under these conditions. The 2-iodopurines are however reduced by zinc and water [152]. The elec-... 

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