really really need some help, been stuck on this for toooo long.

Some Data:

"A" triplet for 3H (2 neighbors)
"B" quartet for 2H (3 neighbors)
"C" singlet for 3H (no neighbors)
"D" singlet for 2H (no neighbors)

Alright here is what i have so far:
im trying to figure out what group can be attached that would cause another singlet. I have this structure so far: CH3CH2COOCH3 where you would expect a quartet, triplet from the ch3ch2 and a singlet from the methyloxy. What are some options of a less electronegative atom then oxygen that will give a singlet but does not have any hydrogens? (I'm stumped on figuring out whaat "D" is) Any help would be superb!!!

To figure out what group can be attached to the molecule CH3CH2COOCH3 that would cause another singlet, we need to consider the types of signals observed in NMR spectroscopy.

In the given data, "C" is a singlet for 3H with no neighbors, and "D" is a singlet for 2H with no neighbors. This means that "C" and "D" are both signals from a group with no neighboring hydrogens.

Based on the structure CH3CH2COOCH3, we can see that there are two possible groups that could correspond to "C" and "D":

1. The methyl group (-CH3) in CH3COO- can account for the singlet "C" signal, as it has no neighboring hydrogens.

2. The methoxy group (-OCH3) in CH3COO- can account for the singlet "D" signal, as it also has no neighboring hydrogens.

Therefore, in order to obtain another singlet signal in addition to the quartet and triplet, you would need to attach a group that has no neighboring hydrogens. Some options for a less electronegative atom than oxygen could be a halogen atom (e.g., fluorine, chlorine, bromine, iodine) or a nitrogen atom. These groups would not have any hydrogens directly attached to them, allowing them to contribute to a singlet signal in the NMR spectrum.

It is important to note that the specific chemical environment and connectivity of the groups can influence the NMR signals observed, so it is always recommended to experimentally verify the results.