• Neuroscience & Pharmacology Discussion Welcome Guest
    Posting Rules Bluelight Rules
    Recent Journal Articles Chemistry Mega-Thread
    FREE Chemistry Databases! Self-Education Guide

  • N&PD Moderators: Skorpio

Is there a maximum amount of permutations a chemical can be drawn differently in 2D?

Nagelfar

Nagelfar

Bluelight Crew
Joined
Nov 23, 2007
Messages
2,527
Location
Vancouver, Washington USA
...not counting sliding scale geometric angle distances on freely rotatable molecular branches and such (but conformation and absolutely differently depicted orientation of those, for instance)...

Does anybody know the maximum number of two-dimensional permutations/ways any one given chemical could be drawn in such two-dimensions? (given they have every common established aspect which has an alternate way of being drawn according to chemical nomenclature?)...

As a project for whom is concerned, could someone maybe just draw a chemical of their choice (doesn't have to contain the potential for max permutations of any conceivable chemical in this second request) that is not dauntingly complex but not overly simple, and see if they can draw out every manner that it can be? This'll circumvent using programs like chemdraw (I suppose?), and it would be interesting to see the other manners in which other users catch what other ways said chemical/molecule could legitimately be drawn in a modern 2D chemist's context that the initial attempting poster overlooked...
 
Last edited:
There are ambiguities in drawing A, the most important of which is that you can't tell whether either of the substituents on the tropane are endo or exo.

But then when trying to make unambiguous skeletal drawings of bridged, polycyclic, chiral molecules, you'll easily end up with a troubled foetus:

220px-Benztropin.png

​
IUPAC publishes a 74 page protocol for Graphical Representation of Stereochemical Configuration
 
seep said:
There are ambiguities in drawing A, the most important of which is that you can't tell whether either of the substituents on the tropane are endo or exo.

But then when trying to make unambiguous skeletal drawings of bridged, polycyclic, chiral molecules, you'll easily end up with a troubled foetus:

220px-Benztropin.png

​
IUPAC publishes a 74 page protocol for Graphical Representation of Stereochemical Configuration
Click to expand...

Thank you much for that pdf link... bringing up the follies of diagram A; would anyone care to fix the image but while in keeping its same basic structure as distinct from diagram B as it now stands?
 
The problem with fixing diagram A is that the tropane is smooshed into a hexagon, and the cocaine molecule will never actually look like that. Also, you'd have to put 3 fat wedges inside a regular hexagon and even with a good vector graphics program, that much clutter will confuse the human eye and also cause some chemistry software to misinterpret the molecule.

So do this thought experiment (or build it with a model kit):

1) Lay a cycloheptane ring flat on a sheet of plexiglass.
2) Number the carbons 1-7
3) Drop a methylamino group on top of carbons 1 and 4 (the ring will no longer be planar).
4) Drop benzoic acid on carbon 6.
5) Drop the ethyl formyl end of methyl acetate formate on carbon 5.
6) Erase the numbers and remove the plexiglass.

I don't have the program that makes the straight lines. I have the welfare version of some commercial program and these polygons are very ugly. Anyways a protonated version of this?



That's kind of how the molecule will actually appear from above (if you were very tiny and could fly). There's ugliness to the irregular heptagon no matter what program you use, but at least the heptagon doesn't have any wedges (which that IUPAC manual will tell you to avoid making any of the bonds on the main ring a wedge).

The biggest caveat with regard to perspective drawings is straightforward: perspective is a difficult
concept. The artwork of M. C. Escher [17] famously demonstrates the ambiguities that can easily
arise from the use and misuse of perspective. Even when used completely properly, perspective diagrams
of molecular entities rely on subtle visual cues to impart significant changes of meaning in portions
of the diagram that are far removed from those cues.
Click to expand...

Most readers will still prefer the perspective diagrams though.
 
Last edited:
seep said:
There's ugliness to the irregular heptagon no matter what program you use,
Click to expand...

I've seen it portrayed as a tetrahedron (if you mean the tropane part). Thank you much for your revision.

Though I have, looking at that image, come up with a QSAR question concerning the molecule: would cocaine still be active as a DRI if the carbon ring was replaced with a second tropane section?
 
You must log in or register to reply here.
Top