Question

How do you name hemiacetals?

Answer 1

A hemiacetal has the general formula ${R^1}{R^2}COR$ , where ${R^1}$ or ${R^2}$ is hydrogen or an organic substituent. Remember that '' $R$ '' is shorthand to denote any carbon chain. The carbon chain can be hundreds of carbon atoms long or as short as one carbon atom. Most sugars are hemiacetals.

Complete answer:
A hemiacetal is a carbon connected to two oxygen atoms, where one oxygen is an alcohol and the other is an ether. Hemiacetals are named substitutively as alkoxy, aryloxy, etc., derivatives of an appropriate hydroxy parent compound, such as an alcohol, and by functional class nomenclature in the same way as acetals using the class name "hemiacetal".
Sulfur analogues of hemiacetals with general structures $R{R'}(SH)(S - {R{''}})$ and $R{R'}C(OH)(S - {R{''}})$ are generically dithio hemiacetals or monothiol hemiacetals, respectively. They are named substitution as alkyl sulfonyl, arylsulfonyl, alkyloxy, or aryloxy, derivatives, as appropriate, of a hydroxy parent compound, such as an alcohol, or of a thiol parent compound. They may also be named by functional class nomenclature in the same way as hemiacetals. Selenium and tellurium and mixed analogues are treated in the same way as their sulfur analogues; generically, they are mono selena hemiacetals, difluoro hemiacetals, selenothio hemiacetals, etc., and are named substitutively as derivatives of a hydroxy parent compound or a chalcogen analogue, such as a thiol or selenol, using prefixes such as alkyl allyL and aryl tellanyl, etc.

Note:
Hemiacetals are formed when an alcohol oxygen atom adds to the carbonyl carbon of an aldehyde or a ketone. When this reaction takes place with an aldehyde, the product is called a 'hemiacetal'; and when this reaction takes place with a ketone, the product is referred to as a 'hemiketal'.