Nomenclature ketones

Nomenclature for aldehydes and ketones. Nomenclature of difunctional molecules containing a carbonyl group and an alkene or alkyne, or two carbonyl groups. 

The suffix for ketone nomenclature is -one the numbering scheme gives the ketone carbonyl the lowest possible number. 

Although substitutive names of the type just described are preferred the lUPAC rules also permit ketones to be named by functional class nomenclature The groups attached to the carbonyl group are named as separate words followed by the word ketone The groups are listed alphabetically... 

In substitutive lUPAC nomen clature cyanohydrins are named as hydroxy deriva tives of nitriles Because ni trile nomenclature will not be discussed until Section 20 1 we will refer to cyanohydrins as derivatives of the parent aldehyde or ketone as shown in the ex amples This conforms to the practice of most chemists... 

Ketones may also be named using functional class lUPAC nomenclature by citing the two groups attached to the carbonyl m alphabetical order followed by the word ketone Thus 3 methyl 2 butanone (substitutive) becomes isopropyl methyl ketone (functional class)... 

It is possible to regard radicofunctional nomenclature, in which the functional class narrie of a compound (c.g. alcohol, ketone, etc.) is cited after the names of the attached radicals, as involving an additive procedure (example 146). This type of nomenclature is gradually falling out of use in favor of the substitutive equivalent [for 146 the substitutive name would be l-(3-pyridyl)propan-l-one]. 

A further anomaly in nomenclature is thebainol, the name applied to the substance formed by the alkaline reduction of metethebainone, and which was at first believed to be formed by reduction of the carbonyl group, but which Gulland and Robinson proved to be a ketone. It is isomeric with dihydrothebainone referred to above, and has been re-named dihydrom tathebainone (Schopf). The interrelationships of these substances are shown by the following formulae —... 

Ketal is an acceptable subcategory term for acetals formed from ketones. It was dropped from lUPAC nomenclature, but continues to be so widely used that it has been reinstated. 

Although a polyfunctional organic molecule might contain several different functional groups, we must choose just one suffix for nomenclature purposes. It s not correct to use two suffixes. Thus, keto ester 1 must be named either as a ketone with an -one suffix or as an ester with an -oate suffix but can t be named as an -onoate. Similarly, amino alcohol 2 must be named either as an alcohol (-0/) or as an amine (-amine) but can t be named as an -olamine or -anritiol. 

Cyclic acetals formed by the reaction of saccharides or saccharide derivatives with aldehydes or ketones are named in accordance with 2-Carb-24.1, bivalent substituent names (formed by general organic nomenclature principles) being used as prefixes. In indicating more than one cyclic acetal grouping of the same kind, the appropriate pairs of locants are separated typographically when the exact placement of the acetal groups is known. 

NADH (reduced nicotinamide adenine dinucleotide) is utilized in biological reductions to deliver hydride to an aldehyde or ketone carbonyl group (see Box 7.6). A proton from water is used to complete the process, and the product is thus an alcohol. The reaction is catalysed by an enzyme called a dehydrogenase. The reverse reaction may also be catalysed by the enzyme, namely the oxidation of an alcohol to an aldehyde or ketone. It is this reverse reaction that provides the dehydrogenase nomenclature. 

The carbonyl group in glucose and ribose is an aldehyde such compounds are termed aldoses. Fructose, by contrast, has a ketone group and is therefore classified as a ketose. Glucose could also be termed an aldohexose and fructose a ketohexose, whereas ribose would be an aldopentose, names which indicate both the number of carbons and the nature of the carbonyl group. Another aspeet of nomenclature is the use of the suffix -ulose to indicate a ketose. Fructose could thus be referred to as a hexulose, though we are more likely to see this suffix in the names of specific sugars, e.g. ribulose is a ketose isomer of the aldose ribose. 

The basic nomenclature for aldehydes and ketones follows that of other organic compounds. The following steps cire the keys ... 

The structure and 2-ethyl-4-methylpentanal nomenclature of some aldehydes and ketones. 

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