Multiplizierende Affixe

[Gast]

Hallo,

hab eine Nomenklaturfrage:

Bis jetzt dachte ich immer, dass man bei "identen unsubstituierten Resten" (also CH3), "di, tri, tetra, etc.", verwendet,

und bei "identen subsubstituierten Resten" (also z. B. Cl) "bis, tris tetrakis, etc.".

Jetzt habe ich aber ein Bsp. gefunden, in dem es bei der substitutiven Nomenklatur "Diisopropylamino", und bei der konjunktiven Bis-(1-methylethyl)amino" heißt.

Kann mir das wer erklären, ich versteh das überhaupt nicht, denn die Reste bleiben ja gleich, egal, nach welcher Art man die Verbindung benennt.

lg,
apfel

[alpha]

Bin mir nicht sicher, da ich kein grosser Terminologe bin und mich wenig um Nomenklatur schere, aber soviel ich weiss, ist "isopropyl" sowieso keine saubere Nomenklatur, d.h. alle wissen, was es ist, aber systematisch ist das nicht.

Aber das beantwortet deine Frage wohl kaum?


Grüsse
alpha

[Gast]

nein, leider nicht, aber trotzdem danke für deine Bemühungen!

lg,
apfel

[alpha]

Gut, dann schauen wir mal, was IUPAC schreibt:

4.5.2.4 [...]
The following names are still used, but only for the unsubstituted groups. These
particular names are also referred to as retained names. If there are substituents
within these groups, systematic procedures must be followed.
Examples
6. (CH3)2CH- isopropyl
7. (CH3)2CH-CH2- isobutyl
8. CH3-CH2-CH(CH3)- sec-butyl
9. (CH3)3C- tert-butyl
[...]
The groups attached to the principal chain are called substituents, and these may
be simple or complex. Simple substituents are formed directly from parent hydrides;
when a simple substituent is itself substituted, it becomes complex as a consequence.
Normal alkyl groups are simple substituents; branched alkyl groups are complex
substituents. However, as exceptions the names isopropyl, isobutyl, sec-butyl, tertbutyl,
isopentyl, tert-pentyl and neopentyl are taken to refer to simple substituents.

4.5.2.5 Multiplicative prefixes. Multiplicative prefixes (Table 4.2) are used when more than
one substituent of a given kind is present in a compound or group. The name of the
substituent is cited as a prefix, and two sets of multiplicative prefixes are used,
depending on whether the substituent is simple or complex.
Basic multiplicative prefixes di-, tn-, tetra-, etc. are used with the names of simple
substituents and retained names. Different or modified prefixes are used with
complex substituents: bis-, tris-, tetrakis-; from tetrakis- onwards the ending -kis is
attached to the basic multiplicative prefix, giving pentakis-, hexakis-, etc. (compare
the use in coordination nomenclature).
Examples
1. 3,3-dimethylpentane
2. 5,5-bis(l,2-dimethylpropyl)nonane
3. 4,4-diisopropylheptane or 4,4-bis(1-methylethyl)heptane

In general, chemists like to use retained names. The shorter an approved name, the
better.