nmr spectroscopy l.o.: state that nmr spectroscopy involves interaction of materials with...

25
NMR spectroscopy L.O.: State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation. Describe the use of tetramethylsilane, TMS, as the standard for chemical shift measurement. State the need for deuterated

Upload: hugo-patterson

Post on 30-Dec-2015

232 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

NMR spectroscopy

L.O.:State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.

Describe the use of tetramethylsilane, TMS, as the standard for chemical shift measurement.

State the need for deuterated solvents, e.g. CDCl3, when running an NMR spectrum.

Page 2: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of
Page 3: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Some nuclei have a magnetic spin: 1H, 13C, 19F

In a strong magnetic field they can line up either with the field or opposed the field.

Page 4: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Different nuclear spins in an external magnetic field

Page 5: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Excitation: a nucleus in its low –energy spin state can be promoted to an upper energy level.

This energy is provided by a radio-frequency radiation.

Relaxation: The excited nucleus will drop back to the lower energy level.

Resonance: the energy provided by the radiation is the same as the energy gap between the tow spin states.

Page 6: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

The magnetic field felt by each nucleus depends on:

o the applied magnetic fieldo Chemical environment. Electrons

surrounding the nucleus generate a magnetic field.

Page 7: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Nuclear shielding – electrons modify the magnetic field experienced by the nucleus

Page 8: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Chemical shift, , is a scale that compares the frequency of an NMR absorption with the frequency of the reference peak of TMS at =0.

Page 9: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Tetramethylsilane (TMS), (CH3)4Si

Page 10: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectroscopy

L.O.:• Analyse carbon-13 NMR spectra to make

predictions about the different types of carbon atoms present.

• Predict the chemical shifts of carbons in a given molecule.

Page 11: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 chemical shifts

Page 12: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Electron withdrawing groups (O, CO, F, N) are less shielding.

The less shielding, the higher the chemical shift.

Page 13: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

How many carbon environments?

Page 14: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectra of propan-1-ol and propan-2-ol

Page 15: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectra of propan-1-ol and propan-2-ol showing peak assignments

Page 16: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectra of (a) CH3CHBrCH3 and (b) CH3COOCH3

Page 17: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

13C NMR TASK 1For each of these compounds indicate the number of signals in the 13C NMR spectrum predict the approximate chemical shift of each signal using the data sheet a)methylpropeneb)propenec)2-chloropropaned)Propanonee)methylaminef)ethyl propanoateg) 1,2-dibromopropaneh)dimethylethyl propanoate i)but-2-ene

Page 18: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

L.O.:• Analyse carbon-13 NMR spectra to make

predictions about possible structures for an unknown compound.

Page 19: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectra of isomer of C3H6O

Page 20: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Structural isomers of the carbonyl isomers of C3H6O showing different carbon environments

Page 21: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Carbon-13 NMR spectra of an aromatic compound with molecular formula C8 H8

Page 22: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

Structural isomers of the aromatic isomers of C8H8

Page 23: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of
Page 24: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of

13-C NMR of butane

Page 25: NMR spectroscopy L.O.:  State that NMR spectroscopy involves interaction of materials with low-energy radio frequency radiation.  Describe the use of