Technique A1: Use of Beilstein Crossfire for Unknown Compound Identification

If you have an unknown compound, there are two types of property that can be readily measured using appropriate instruments

1. The Accurate mass, from which a molecular formula can be computed. Other physical properties such as the boiling or melting point are easily obtained, along with more specific properties such as the optical rotatation. Armed with just these few properties of the unkown substance, a search of the Beilstein database can often yield two or three candidates for further refinement.
2. Spectroscopic information such as the ¹H or ¹³C spectra. This is particularly useful if the substance might be a previously unreported compound. "Expert" systems exist (e.g. the SpecInfo system) which can do a fair job of deducing a structure based purely on such spectroscopic information.

1. Firstly, you will need to acquire an account for using Beilstein Commander. You will have been sent an email in your when you first registered in the College indicating your personalised ATHENS ID, of the type iclXXXXX, where XXXXX should be similar, if not identical, to your email login ID. along with an initial password. To register your intended use of Crossfire, you will need to connect here.
Remember on this page to indicate you are part of the Chemistry department. Once this is done, connect to Crossfire (this only works properly on a Mac) or start up the Beilstein Commander Program on the computer you are using in the normal way.
2. If you have only an accurate mass for your unknown compound, you can convert it to a formula using this program . Before you use it, go to Settings to apply to Calculation, and set the maximum number of atoms of each type to the appropriate limit.
3. Click here to start up Crossfire. You will have to enter your Crossfire account and password as allocated above.
4. The following screen should be visible
   
5. Click on the menu item ringed in red, when the FACT editor will open
   
6. Enter the physical properties of your compound as shown. If you have no measured value for the optical rotation, do not enter these fields. When finished, click on the menu item ringed in red. Note that the your search will depend on the accuracy of your measured properties. If your mp is off by say 5 degrees, your search will only succeed if you increase the limits of the value. This might in turn result in many more hits. Its a balancing act you will have to perform! Note that the boiling point field is specified as bp (assumed atmospheric) and bp.p for non atmospheric (ie 120.300-125.300 for a range of 5 degrees at 300 torr). Other property fields could include den (density) or ri (refractive index). Clearly, the more properties you can specify, the better the chance of obtaining a unique hit. Do remember however that these properties might not be recorded in the literature for many compounds.
7. From the display that appears, click Start and wait for the search to complete.
8. Display the hits
   
   You can view the structures in various ways. If you have many hits, select Short display. For the parameters defined above, you should only get a single hit. From that, you should be able to identify the unknown compound. Literature citations to the compound are available in Crossfire, and should be consulted (if possible) for further details.