Can you explain how you can tell how many C environments there are in an organic molecule?
If you're given a C-NMR spectrum, count the number of peaks that are present as this will equal the number of environments. If you've been given a diagram of a molecule and asked to count, here are some things you need to remember:- Not each individual Carbon atom is a separate environment- What is bonded to a Carbon atom adjacent to the Carbon atom in question also affects the number of environments. In the above picture for example, 2-methyl-2-butanol has 5 Carbon Environments. Remember, 5 Carbon atoms doesn't necessarily mean 5 environments.While the 2 CH3 groups on the ends of the molecule are identical, we must look at the Carbon atoms next to them. The first C (enviro shown in dark blue) is bonded to another C(enviro is red) which is bonded to a Hydroxyl group and a Methyl group. This differs from the C on the last CH3 group as it's adjacent C is only bonded to a CH2 group. The remaining three Carbon environments should be easily spotted; 1 C bonded to 3 H, 1 C bonded to OH, and 1 C bonded to 2 H. Isopropyl Propanoate contains 6 C atoms, and possesses only 5 C enviros. The 2 Methyl groups(purple) are identical, and are also attached to the same carbon atom. This part of the molecule is symmetric, so the two Methyl groups are considered one environment. The other C atoms are obviously very different and bonded to different C atoms and environments. This gives us a total of 5 C environments. - Jae.