Carbon-Carbon Bonds Get a Break

Herzel Drew R. Labongray                                                          September 28, 2016

10 - Graviton                                                              Article Summary with Resources

Carbon-Carbon Bonds Get A Break

        Carbon–hydrogen (C–H) and carbon–carbon (C–C) bonds are the two fundamental linkages of organic molecules (Goldman, 2010) yet they are also the hardest to control. That is why it was a breakthrough when they found out that C - H bonds can be broken by transition metals. If C - H bonds are hot over the scientific community, C - C bonds are not.

        There are a few ways to break C-C bonds and they all need to have the metal near them, in other words, you need help from others to do it. An experiment where there was no given assistance to the C-C bonds was done to aromatic molecules quinoxaline which made the quinoxaline even stronger. But if you compare it to the all-carbon ring, it has 2 nitrogen atoms on its rings, which you will have to remove using hydrodenitrogenation to avoid problems the nitrogen will cause. Initially, the researchers found that when Molybdenum(Mo) reacts with quinoxaline it will form molybdenum-quinoxaline complex, which is nice but the quinoxaline bonds are still unbroken.

        The researchers the tried the element below Molybdenum, Tungsten(W), which acts similar to Mo but is more aggressive when it comes to breaking bonds. They found that the W inserted itself in the C-C bond between the 2 nitrogen bonds and turned the nitrogen-containing ring quinoxaline with 6 atoms to a tungsten-containing ring quinoxaline with 7 atoms.

        Scientists proposed a method on how the tungsten does this. First, it inserts itself to one of the carbon atom of the C-H bonds that eventually undergo C-C addition. Second, it inserts itself to the other carbon atom that will undergo C-C addition, known as beta-hydrogen elimination. The two H atoms that were loosed will form a H molecule. The final products contains two tungsten-carbon-tungsten-nitrogen linkages known as metal isocyanide groups, which is thermodynamically stable and much more easier to break compared to the original C-C bonds.