This is not helpful

by James

in Nomenclature, Teaching

What’s my least favorite thing about organic chemistry? Nomenclature, by far. I  loathe doing nomenclature. Don’t get me wrong, it’s a means to an end, it’s necessary. But what I loathe about it is how arbitrary it can be – particularly the non-IUPAC names. This makes it tough to teach.

What’s the number one rule for naming hydrocarbons?  Find the longest carbon chain containing the functional group, and use that as the root. Seems really simple, right? Something that would be hard to confuse people with?

You would be wrong. This is from “Organic Chemistry: A Brief Course, Third Edition”, by Atkins and Carey.

1-not helpful

Am I missing something here?

What’s the deal with naming this as 1-methyl butyl iodide? What’s the longest carbon chain? Five.

There’s a name for 1-methyl butyl, okay?  It’s pentyl.

2-pentyl iodide, to be exact, if you’re going to name it that way.

When I see things like this  – and do damage control with students who are having a hard enough time with the course material as it is, without dealing with these types of contradictions  – it makes me want to take out a few millilitres of Muscalure ® and swab it generously over the car of the editor responsible for this. Preferably on a nice windy day.


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{ 4 comments… read them below or add one }

Peter M

What about 2-iodopentane?

I have lots of trouble with nomenclature too – my lecturer uses, apparently for no reason, systematic nomenclature on one slide and then ‘common’ nomenclature on another.

I prefer to use the IUPAC nomenclature because its clear.


appears on my tute sheet.

I’ve never been taught what ‘carbinol’ is. The lecturer has never mentioned it. Nor in my last session of Org Chem.

I had to look it up, apparently it is another name for methanol.

Why not just call the compound


I don’t have the liberty of using the ‘net in an exam…so its very frustrating.

Thanks for your nomenclature sheets, they’re very helpful. Also this website is absolutely amazing – there’s so much in Organic chem that I wish was covered in more detail, especially reaction mechanisms and drawing compounds.

I feel like I’m just picking up bits and pieces of ways of drawing compounds, and mechanisms…and it feels a bit slapdash. I wish it were more rigorous.

Robert Grossman has a book “The Art of Drawing Reasonable Organic Reaction Mechanisms” that helps somewhat.

Thanks again


Peter M

Also, here’s another one:


I would have called this ‘propanal’.

or maybe, ‘propanaldehyde’.

Why priopIONaldehyde? Wikipedia says this is the ‘systematic name’ and the ‘IUPAC name’ is propanal. I don’t know the difference between the systematic name and the IUPAC name. I thought they were the same thing?


Peter M

OK one last example:

n-propyl alcohol

That’s what my tute sheet calls 1-propanol.

The IUPAC name is propan-1-ol.
Wikipedia lists the following ‘other names’:

Propionic alcohol
Propionyl alcohol
Propyl alcohol
Propyl hydrate
Propylic alcohol

It’s crazy. Propyl hydrate? Propylic alcohol? I dunno, if I was told to draw those i’d be set on the wrong track.
Nomenclature is a bizarro world. I truly wish they’d have one naming standard which they’d stick to (at least in lectures and tutorials).



Awesome comment. Thanks for all those examples… this is exactly why I hate nomenclature.


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