Sciencemadness Discussion Board

Online chemical structure analysis?

Electra - 21-12-2013 at 13:38

I've played around when ChemSpider. For a lot of molecules it can give predicted boiling/melting points and that sort of related data, but is there any sort of program I can buy or download, or use online, that can analyse a chemical structure of a hypothetical molecule and predict properties about it?

TheChemiKid - 21-12-2013 at 13:46

Well, there is Avogadro. This can model compounds, and tell how many kJ per mole it takes to synthesize the compound.

Electra - 21-12-2013 at 14:07

Interesting! Thanks for this!

Do you know if this program can predict boiling/melting points, or pKa values?

kavu - 21-12-2013 at 14:45

Quote: Originally posted by TheChemiKid  
This can model compounds, and tell how many kJ per mole it takes to synthesize the compound.


It doesn't actually tell that. The energy is just a measure of the systems potential energy with a given force field. To get to melting points/pchemical data you need to have more sophisticated calculations. You could in theory run ab initio calculations to give you melting points, but that's immensely complex.

Usually for properties like pKa, melting points and so on statistical stuff is used. Some structural databases like reaxys can give sophisticated guesses on these properties, but it's hardly a trivial thing to do.

Electra - 21-12-2013 at 15:48

Is it possible to submit various molecule structures to these databases and have calculations run on it?

kristofvagyok - 21-12-2013 at 17:13

Quote: Originally posted by Electra  
Is it possible to submit various molecule structures to these databases and have calculations run on it?

Sure, it only depends, that what kind of calculations would be needed. There are several software that could calculate a few things, just a few from these: ChemDraw, Spartan, Gaussian.

The problem is, that it should be figured out, that what and how could be calculated. So if you are new in this, that it will take a few day, to calculate something useful.

P.S.: is here anyone who can predict a enthalpy of vaporization/boiling point or something like that for organics? I would need some data for not yet described compounds...