Hemiacetal | 食品添加物合法業者資訊網

AhemiacetalorahemiketalhavethegeneralformulaR1R2C(OH)OR,whereR1orR2ishydrogenoranorganicsubstituent.Theygenerallyresultfromthe ...

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Organic compound of the form >C(OH)O–

In organic chemistry, a hemiacetal or a hemiketal has the general formula R1R2C(OH)OR, where R1, R2 is hydrogen or an organic substituent. They generally result from the addition of an alcohol (a compound with at least one −OH group) to an aldehyde (R−CH=O) or a ketone (R2C=O), although the latter are sometimes called hemiketals. Most sugars are hemiacetals.

According to the IUPAC definition, in R1R2C(OH)OR R1 and R2 may or may not be a hydrogen. In a hemiketal, neither R-group can be a hydrogen. Hemiketals are regarded as hemiacetals where none of the R-groups are H, and are therefore a subclass of the hemiacetals.[1] The Greek prefix hèmi means half, refers to the fact that a single alcohol has been added to the carbonyl group, in contrast to acetals or ketals, which are formed when a second alkoxy group has been added to the structure.[2]

Cyclic hemiace...