[jena]

Hi,

I'm having a hard time with 1H NMR. My question is:

What is the C6H14O isomer with 1H NMR(ppm), 3.4(2H,q). 1.2(9H,s), 1.17(3H,1)?

I'm really confused about the questions. Could someone please help, at least help me step by step if you can, so that I can figure out my own answer.

Thank You

P.S. I looked over past forum questions and still didn't understand.

[dexangeles]

Let's make this as simple as possible..

1. The location of the signals depend on the shielding of the Hydrogen.  The less shielded the proton, the more your peak is gonna be to the left of te HNMR spectrum.

    example: CH₃X, the shielding of the protons increases as the
                   electronegativity of X decreases

                   CH₃CH₂OCH₂CH₃
                   the Hydrogens of the CH₂ are less shielded than the H of
                   CH₃

2. The number of signals tells you how many different protons there are.  On the above example there should be 2 Peaks in the HNMR

3. The intensity of the signals (based on the area of the peak), tells you te relative ratios of the different protons

4.  The splitting of the peak tells you ow many protons are vicinal to the one giving the signal.  

     example: the CH₂ peak in the above example should give 4 splits
                   and the CH₃ should give 3 splits.  On another example
                   CH₃OCH₃, there should only be 1 peak with no
                   splitting.


hope this helps

[Winga]

3.4(2H,q). 1.2(9H,s), 1.17(3H,1)

1.17(3H,1), "1" means singlet?

Make sure the data you provided is accurate.

[Winga]

I think "1" means "t", triplet, right?

The sample should be:
ethyl 1,1-dimethylethyl ether / 2-ethoxy-2-methylpropane

[Garneck]

(9H, singlet) is a sign of a t-buthyl group in the compound. Or at least that's what I think. The 9 hydrogens don't conjugate (don't know if this is the correct word here, as you know, my chemical english sucks) with other hydrogens because they're too far apart...

Code: [Select]

     CH3
        |
     CH3 -C -
        |
       CH3


[Garneck]

Exactly the same compound I was thinking of, Winga  

[Garneck]

Edit: no hotlinking allowed from SDBS

Parameter     ppm  Hz

      D(A)         3.418
      D(C)         1.169
       J(A,C)          7.0
     
      D(B)         1.200

[Winga]

What is the C6H14O isomer with 1H NMR(ppm), 3.4(2H,q). 1.2(9H,s), 1.17(3H,t)?

1.
9 equivalent protons, singlet, chem. shift around 1 ppm, is usually a tert-butyl group. (it can also be 3 chemically equivalent methyl groups)

2.
Chem. shift 3.4 ppm, methylene protons, O-C-(H), negative inductive effect

3.
Chem. shift 1.17 ppm, methyl protons are far away from O (also tert-butyl protons), -ve inductive effect decreases.

[jena]

Hi,

Thanks everyone for the help dealing 1H NMR, but I have another question dealing with it.

1. The C6H14O isomer with 1H NMR(ppm), 3 .5(2H, d), 2.5(1H,broad s), 1.4(5H,m), 0.9(6H,t).

I understand that because of the 3.5 it can be identified as an ether, alcohol, or hydroxy group, and with the 1.4 as a tertiary group, and the .9 as a primary group, but  I can't figure out what the 2.5 may be. Could you please help.

Also I have a question dealing with 13C NMR

1. The C7H16 isomer with four 13C NMR and negative DEPT-135 signals.

What does all that mean?

Sorry for all the questions.

Thank You  

[Winga]

1. The C6H14O isomer with 1H NMR(ppm), 3 .5(2H, d), 2.5(1H,broad s), 1.4(5H,m), 0.9(6H,t).

I understand that because of the 3.5 it can be identified as an ether, alcohol, or hydroxy group, and with the 1.4 as a tertiary group, and the .9 as a primary group, but  I can't figure out what the 2.5 may be. Could you please help.

The data is quite strange!
About 1.4(5H,m), I think there should be overlapping of 2 signals (2 types of proton), please provide more details.

I think the chem. shift at 3.5 should be the protons of O-C-H (check any chem. shift list), and at 2.5 should be hydroxy proton (because of broadband, and the chem. shift of this proton can vary in wide range).

The structure I guessed is like this:

[Mitch]

Jena: Go to our links section and there you'll find "NMR/Mass Spectra Database" They'll have what you need.

[jena]

Hi,

How can you figure if a group such as OH can be considered

Ether with the range of 3.3-3.9
Or
Alcoholic hydroxyl with a range of .5-5.0
Or
Alcohol with a range of 3.3-4.0

I'm using my textbook for the ranges, and I'm kind of limited with the number of ranges I can use for the C6H14O isomers, so it get kind of confusing when they are so close in range. What should I look to help me, determine my structures better.

Thank You

[Winga]

How can you figure if a group such as OH can be considered

Ether with the range of 3.3-3.9

Chem. shift: 3.5ppm (2H, d)

If ether, there should have -C-O-C-. either the 2 protons attached to one carbon or each proton attaced to each carbon. The 2 protons are chemically equivalent.

2 examples shows that when the 2 protons are chemically equivalent, the splitting doesn't match.


Sorry, I don't know what's the difference between Alcoholic hydroxyl and Alcohol.

[786mine]

hope this helps