# How can I tell if a certain carbon/hydrogen molecule can actually exist?

My 11 year old daughter asked me if the following compound exists in real life, and if so, what is it called. Not only do I not know, I have no idea how to find the answer to such questions. Any ideas?

• It doesn't exist, although it looks very cute. You might want to have a look at the resources provided by the Royal Society of Chemsitry and the American Chemical Society for different age groups, including curious and creative girls at the age of 11. – Klaus-Dieter Warzecha May 3 '16 at 15:27
• Oh, and by the way: Welcome to Chemistry.SE! – Klaus-Dieter Warzecha May 3 '16 at 15:28
• ChemDraw tells me that "A name could not be generated for this structure". :( I am a little bit disappointed – orthocresol May 3 '16 at 15:57
• Your compound is called 1,2,3-butatriene and belongs to the group of cumulenes :) – Klaus-Dieter Warzecha May 3 '16 at 17:47
• @SendersReagent Please have a look at the edit history of the question. Initially, H and C were interchanged ;-) – Klaus-Dieter Warzecha May 5 '16 at 4:42

When drawing organic structures Carbon should have 4 "lines" coming from/to it while Hydrogen can have only 1 covalent bond. So if you could draw your molecule following these rules, it probably can exist. Here is an example:

H       H
\     /
C=C=C
/     \
H       H


Alternatively there could be this structure with the same number of "lines" coming from/to Carbon:

  H   H
\ /
C     H
/ \   /
H   C=C
/   \
H     H


As for the naming.. It's more complicated since it would depend on whether there is only one = bond or more than that. You could watch CrashCourse Organic Chemistry intro that talks about some naming conventions. But if you're stumbled, you could count the number of Carbons and Hydrogens and google for it: C3H4 or C3H6.

• You've missed a carbon in the first structure (assuming we're just swapping C/H around). Also I'm not clear how you get the second one - are you saying it has the same valence sum or something? – gilleain May 3 '16 at 16:03
• Of course, it's not particularly relevant, but I would have thought that cyclobutane was 'closer' to the original structure in terms of overall bonds (although that is C4H8, or course). – gilleain May 3 '16 at 16:07
• Answer is more or less obsoleted since the edit to the question. – Jan May 4 '16 at 16:25
• Hm.. I don't see how it becomes obsolete. This answer wasn't based on the picture drawn by Rolandus, so even after the edit it's up-to-date. – Stanislav Bashkyrtsev May 4 '16 at 17:04

There are sites you can use like scifinder, chemistry journals, and even just going to a chemical supplier's website, most of them have places where you can draw a chemical and they will link you to it. If they have it then it exist obviously, but if they do not sell it, it may be too dangerous or unstable to ship, thus you would have to go to the journals.

This chemical does exist, 1,2,3-butatriene. I'm not saying it is common, but it can be made.

As a chemist, when asking myself if something exists, I open SciFinder, draw the structure, select exact search and single component and hit find. The caveat is that using SciFinder costs quite a large amount of money. (Yes, a really large amount of money, although I don’t know the actual figure.) If it has been published or proposed, SciFinder will tell you the paper.

Another test is checking out whether Sigma Aldrich sell it. Their catalogue is in no way complete because it only contains shipable items, but it is one of the most comprehensive to the best of my knowledge. You probably don’t want to check the prices, though. The caveat here is that you need a name first.

I am unaware of any website or freeware program that lets you draw almost anything and search for it or get a name. The problem is that knowing whether something exists (i.e. was published) required indexing all the journals in which publications happen, and all the way back to the mid 19th century. You cannot simply machineread everything; it will be in different languages sometimes with antiquated spelling, compound names will be all over the place, structures proposed and revoked. For every structure, you would need to render it in a machine-parseable format. The Chemical Abstracts Service (CAS) of the American Chemical Society (ACS) was founded in 1907 and has since systematically scanned journals to build up a repository of structures including a unique CAS number for every compound known (or proposed). This made it possible for them to digitalise that information and launch the SciFinder. That is 109 years of work steadily growing. It cost so much money that I just don’t see a freeware solution approaching.

You can use REAXYS https://www.reaxys.com/reaxys/secured/search.do similar to SciFinder to know actually this compound exist with out getting registered as paid member. I often use this site before conducting any reaction to get some idea about the reaction condition extra.. I hope this would be helpful...