Hydrogen Bonding Question

[vcuchic]

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Hey Guys,

Here's a question I got wrong on the Kaplan DAT Book. I think it might have something to do with the inductive effect, but I'm not 100% sure what that even is. But I do know that for hydrogen bonding, a hydrogen must be connected to F, O, or N...😛
Thank you for all your help in advance!

Question:
Which of the following compounds is NOT capable of hydrogen bonding?

a) C4H11N
b) C4H9NO
c) C4H7F3
d) C4H8O2
e) C4H10O

Answer:
c) C4H7F3

 

[nate28]

It's been a while since I've done o-chem, but I thought that N, O, and F had to be bonded to H to have hydrogen bonding. If each F i bonded to the C skeleton, then it is not bonded to H and can't hydrogen bond. I hope this is right... 😕

 

[DrBowtie]

Yup.
An H needs to be bonded to an electronegative atom to develop partial charges used for H bonding.

 

[s0chon02]

Question:
Which of the following compounds is NOT capable of hydrogen bonding?

a) C4H11N
b) C4H9NO
c) C4H7F3
d) C4H8O2
e) C4H10O

Answer:
c) C4H7F3[/QUOTE]

Like the others said above, hydrogen must be bound to F, O, N atoms directly to have hydrogen bonding. All the compounds have that cept for c.
TO break it down...
a) if you draw it out, amine is between carbons, and nitrogen has one hydrogen attached to it.

c-c-n-c-c
H
b) if you draw it out,
c-c-c-n-c=0
H
d)
c-c-c-c-oH
(where fourth carbon is double bonded to o)
e)
c-c-c-c-oH


H

 

[vcuchic]

hmm okay...
so i guess the only way to figure this type of question out is to draw all the molecules out?
Is there a more time-saving way to go about this?

ooh but dilemma~
For choices such as choice B --> C4H9NO
How do you know what this molecule looks like?
There is a myriad ways of drawing this.

For instance, it could be drawn this way

o
c c n c
c

(There is a double-bonded O to the 2nd carbon)
(The nitrogen is bonded to the carbonyl carbon and two CH3 groups)

So for this case, there would be no hydrogen bonding right? (Since no H is connected to either N or O).