Do you ever wonder how chemists know if their experiment worked? Well, one of the most common techniques is Nuclear Magnetic Resonance (or NMR). It is very similar to MRI, except nuclei at several frequency can be obtained, and it is very popular, specially amongst synthetic chemists.
This weekend, I slaved away collecting Selective Inversion Recovery (SIR) data. That is, you are able to pinpoint a certain hydrogen (or in my case, another lovely nucleus, fluorine) in your molecule and watch it exchange with others. This occurs if you have two or more distinct nuclei that exchange with each other.
How does SIR NMR work?
Well, think about it this way. Think about a group of 100 hungry and drunk, maybe high, college students. It is their first week of college, and they are doing the typical freshman crazy shenanigans. So, imagine that out of 100 of these drunk students, about 30 of them have their pants off at a certain time. Now, these can put their pants back on, but even if they put their pants on or take them off there are always 30 of these college students without pants on (why, oh why?). Now imagine if you feed all of the students with pants off at a certain time. These are not hungry anymore, although eventually they will. Because they keep, for some reason, putting their pants on and off, there will be students with pants on who have also been fed (they were fed when their pants were off, because they used to belong to that crazy bunch). If over time you look at the college students who are not hungry with and without pants, you will be able to know at which rate these students take their pants off and put them on.
Yes, I know, weird analogy, but that’s the only way I could come up with it.