Talk:E–Z notation

Geocities
Although I'm not the original author who added the Geocities link, I'm unclear on why it was deleted. I've read through the webpage and it appears to give a more thorough, in-depth discussion of the EZ system than the quick, almost summary, overview presented in the WP article. JeramieHicks (talk) 19:46, 3 October 2008 (UTC)
 * See WP:VERIFY for the kinds of sources used in the editing of science articles at Wikipedia. If the Geocities is a good read, then it also was cribbed from somewhere, and it is that authoritative somewhere that we want to read, and summarize, and cite here. Le Prof 50.179.252.14 (talk) 21:12, 2 March 2016 (UTC)

three of four
Currently, the article says this notation can be used for double bonds with "three of four" substituents. Is that a typo for "three or four" or rather "up to four"? --Una Smith (talk) 02:26, 14 March 2009 (UTC)


 * Fixed with "three or four". JeramieHicks (talk) 21:12, 8 April 2009 (UTC)

Edits of this date
Needed additions: The E-/Z- nomenclature applies not only to substituted alkenes, but also, applies (unequivocally) to any disubstituted system with an sp2-hybridized (e.g., element-element, e.g., carbon-carbon double) bond; hence, it is used routinely, even overwhelmingly, in the pedagogy of modern aldol reaction mechanisms, such as the Mukaiyama, to describe these enolate reactants. There is much discussion of aldols in Wikipedia, including with syn-/anti- product descriptions arising from E-/Z-enolates. Hence, images and text describing stereochemical cases other than alkenes/olefins are needed in this article. See for instance,, for a source to write these additions.

Cheers, Le Prof 50.179.252.14 (talk) 21:06, 2 March 2016 (UTC)
 * Please also look at or add images of tri- and tetra-substituted cases—since the opening sentence explicitly mentions these—and then read through the prose for its general applicability to these cases as well. (As it stands, the article's text only makes sense for the simplest of all cases, that shown in the single image, and so again, the scope is too narrow for such a general article.) Le Prof 50.179.252.14 (talk) 21:20, 2 March 2016 (UTC)

'extension of cis/trans notation'
Combined with the example given, it would seem to imply that E would generally coincide with trans and Z with cis. At the very least, we need to give an example where this is not the case (e.g. 2-bromobut-2-ene, where the E isomer would be the cis isomer). (And we should really expand this beyond the basic cases.) Double sharp (talk) 04:11, 31 July 2016 (UTC)
 * My thinking is that since the the complexity of E-Z notation comes from assigning priorities (as far as I know), we can just merge this article with Cahn–Ingold–Prelog priority rules and make complex examples that illustrate both CIP priority rules and the E-Z notation. (similar to the current examples for R/S assignments in the CIP priority rules article)  Galobtter  Talk to me! 08:03, 31 July 2016 (UTC)