How many types of protons? (^1 H NMR)

[2h2o]

Homework Statement

How many types of protons are present?

Homework Equations

compound 1:

CH₃CH₂OCH₂CH₂CH₂CH₂CH₃

and

compound 2:

CH₃CH₂CO₂CH₂CH₃

The Attempt at a Solution

Compound 1:

Arbitrarily assigning hydrogens which see a unique environment, left to right as appropriate.

CH_3(A)CH_2(B)OCH_2(C)CH_2(D)CH_2(D)CH_2(E)CH_3(A)

My solutions manual claims that there are seven types of ¹H in this molecule. I was under the impression that the high electron affinity of the oxygen will only deshield atoms ~1 sigma bond away. Is this impression false?

Compound 2:

First of all, this structural formula appears to me to describe an impossible molecule. Neither O atom has enough bonds to satisfy their "octet", yet to meet this criteria would require an isomer.

Moreover, even if I draw this out as described, using the method above:

CH_3(A)CH_2(B)CO₂CH_2(B)CH_3(A)

Noting the symmetry of the molecule, I see two types of ¹H, but my solutions manual claims four.

Where am I going wrong?

 

[Borek]

1 - it is not only oxygen that changes shielding, you have to look at the other end - and clearly -CH₃ is different form -C₅H₁₁

2 - have you ever heard about esters?

 

[2h2o]

Thank you for the hint on looking at esters--we've only just scratched carboxylic/carbonyls. But drawing it in ester form makes sense.

re #1:

It's not clear to me why the "D" hydrogens aren't the same. All of the "D" hydrogens each "see" four hydrogens on adjacent carbons across the C-C sigma bond.

 

[Borek]

They are very similar, but NMR is not about only the closest proximity (although the closest is the most important).