Some Chemical and Stereochemical Consequences of Enolization

Further chlorination of the chloromethyl ketone gives the corresponding trichloromethyl ketone, which then undergoes hydrolysis to form chloroform. 

Purification of drinking water, by adding CI2 to kill bacteria, is a source of electrophilic chlorine and contributes a nonenzymatic pathway for a chlorination and subsequent chloroform formation. Although some of the odor associated with tap water may be due to chloroform, more of it probably results from chlorination of algae-produced organic compounds. 

A number of novel reactions involving the a-carbon atom of aldehydes and ketones involve enol and etiolate anion intermediates. 

Substitution of deuterium for hydrogen at the a-carbon atom of an aldehyde or a ketone is a convenient way to introduce an isotopic label into a molecule and is readily carried out by treating the carbonyl compound with deuterium oxide (D2O) and base. 

Only the a hydrogens are replaced by deuterium in this reaction. The key intermediate is the enolate ion formed by proton abstraction from the a-carbon atom of cyclopentanone. Transfer of denterium from the solvent D2O to the enolate gives cyclopentanone containing a denterinm atom in place of one of the hydrogens at the a carbon. 

In excess D2O the process continues until all four a protons are eventually replaced by deuterium. 

After the compound shown was heated in D2O containing K2CO3 at 70°C the only signals that could be found in its NMR spectrum were at 8 3.9 (6H) and 8 6.7-6.9 (3H). What happened  

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