Organic chemistry Ethers to isocyanates

These compounds contain the characteristic ether linkage C-O-C, and can be thought of either as alcohols in which the hydrogen atom of the hydroxyl group is replaced by an alkyl group, or as alcohol anhydrides . Diethyl ether and some other ethers are made by a dehydration reaction  

This proceeds via the esterification of ethanol by sulphuric acid. Alternatively the dehydration can be carried out over aluminium oxide at 240-260° C under high pressures. 

In spite of this resemblance to anhydrides, ethers are very resistant to hydrolysis, and heating under pressure with dilute sulphuric acid is required to bring about 

The ether linkage is more readily broken by heating with halogen acids, particularly hydrogen iodide  

The oxide or epoxide ring, R—CH----------CH2, which, at first sight, 

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ORGANIC CHEMISTRY ETHERS TO ISOCYANATES 47 Aldehydes and ketones... 

When ultrasonihcation (US) is applied to the reaction of a bromobenzene with t-butyl isocyanate and butyl lithium in diethyl ether or THF, a considerable improvement in time and yield is obtained addition of DMF at a low temperature induces cyclization [3184a). The use of ultrasonihcation in organic chemistry has been reviewed [B-58, 3615, 3646]. 

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