DescriptionFatty acid carbon numbering.svg |
English: Carbon numbering schemas for fatty acids:
- Systematic IUPAC numbering () starting from 1 at the carboxyl carbon (blue).
- Old Greek letter labels () starting at the carbon after the carboxyl (green).
- Omega-minus numbering () starting at the end opposite to the carboxyl (red).
The position of a double bond is always the carbon closest to the carboxyl, even in the omega numbering. Thus a acid with 18 carbons (as shown) has the bond between carbons and .
A common mistake is to say that the last carbon is . Another common mistake is to say that the position of a bond in omega-notation is the number of the carbon closest to the end. For double bonds, these two mistakes happen to compensate each other. However, for substitutions and other purposes, they don't: a hydroxyl at is at carbon 15, not 16.[1]
Note also that the "−" in the omega-notation is a minus sign, and should in principle be read "omega minus three". However, it is very common (especially in non-scientific literature) to write it "ω-3" (with a hyphen/dash) and read it as "omega-three".
Eesti: Süsinikuaatomite nummerdamine.
Galego: Numeración dos carbonos dos ácidos graxos; neste caso nun ácido graxo de 18 carbonos. Os números sistemáticos ( IUPAC) están en azul. A notación omega está en vermello. A notación con letras gregas está en verde.
Latina: Acidi adipati structura: sinistra acidum carboxylicum cum atomo carboni numero caeruleo 1, dextrorsum catena aliphatica cum carboniis numeris caeruleis increscentibus. Numeri rubri ad ultimum carbonium nomine omega spectant: hoc ultimum enim descriptionis qualitatis propriae sui numero quoque 1 (rubro) numeratur. Nota cursum numerandi hic contrarium esse.
Тыва дыл: Стеаридинниг кислота (Атомнарның физиологтук дугаарлаан ёзузу кызыл өң-биле, а химиктиг — көк өң-биле көргүстүнген). |