A) These Hydrogens have no three-bond neighbors and no coupling, so they show up as a singlet. They are relatively upfield because they are not directly attached to the alkene double bonds.
B) Hydrogen B couples with Hydrogen C, so the splitting pattern is not a singlet. Hydrogen B is relatively downfield because of the alkene, which is electron rich and deshields Hydrogen B.
C) Hydrogen C couples with Hydrogen B, so the splitting pattern is not a singlet. Hydrogen C, like Hydrogen B, is relatively downfield due to the alkene, which is electron rich and deshields hydrogen C.
D) Hydrogen D has no three-bond neighbors nor does it exhibit any long range couplings, so it shows up as a singlet. Its chemical shift is similar to Hydrogen A; both are upfield because they are not directly attached to the electron rich alkene bond. Hydrogen D is more upfield than Hydrogen E because it is trans to the electronegative Bromine atom.
E) Hydrogen E also has no three-bond neighbors and does not exhibit coupling; therefore, it shows up as a singlet. It is slightly more downfield than Hydrogen D because it is cis to the electronegative Bromine atom.
Dienone 11
A) Hydrogen A is the only Hydrogen in this molecule that has no Hydrogen bond neighbors, so it shows up as a singlet. It is relatively downfield because it is directly attached to the electron-rich alkene.
B) Hydrogen B has multiple Hydrogen-neighbors; therefore, it shows up as a multiplet. It is relatively upfield because it is not directly attached to an alkene.
C) Hydrogen C also shows up as a multiplet, and is higher upfield than Hydrogen B because it is further away from the alkene and ketone bond.s
D) Hydrogen D has a higher coupling constant than Hydrogen E because it is trans to Hydrogen F, therefore, its coupling constant is higher than that of hydrogen E.
E) Hydrogen E has a lower coupling constant than Hydrogen D because it couples with hydrogen F, to which it is cis.
F) Hydrogen F couples with both Hydrogen D and E and therefore has two coupling constants and shows up as a doublet of doublets. F is the most downfield because it is directly attached to the alkene bonds and is close to the ring.
