Basics
Protons and neutrons behave as if they are_______
Spinning
Identify ________ _______ protons in a compound
chemically equivalent
Shielded:
Deshielded:
Shielded: electron-dense environments, upfield, low frequency
Deshielded: Electron-poor environments, downfield, high frequency, more energy to flip electrons
What is integration referring to?
protons giving rise to a signal, relative
Formula for spillting
n+1
n= neighboring protons
What number of protons/neutrons must a compound have? Why?
Easy way to find signals in a molecule?
Look for symmetry or a plane of symmetry
Where do signals appear from in HNMR?
0-about 12 ppm, graph of shifts given during exams
How to calculate integration?
lowest value on NMR spectrum over the largest value. Multiply the fraction to get a whole number that corresponds to each signal.
Rule for determining what protons spilt others
What type of energy does NMR use and what is it doing to protons/neutrons
Radio waves; creating a magnetic moment/field
How many signals are in phenol?
4
Find the most upfield/downfield carbon of:
3-pentanone
downfield: carbon 2 & 4
Upfield: carbon 1 & 5
What would the NMR spectrum show for integration of the signals produced by 3-pentanone? Explain the actual integration.
two signals that are chemically equivalent. The NMR would show an integration of 2:6. The actual ratio is 4:6 creating the signals
Why are is there so much splitting in triplet?
protons can align with/against the magnetic field in many ways. Both with, both against, one with one against
Beta spin state:
Alpha spin state:
Energy levels?
Beta: opposing magnetic field, higher energy
Alpha: aligned with magnetic field
How many signals are in meta dimethyl benzene?
What are the chemical shifts of the carbons in propanoic acid?
carbon 2 is most downfield: about 12ppm
carbon 3 is most upfield: about 1 ppm
What must be known to calculate the absolute ratio of integration?
Molecular formula
What is the splitting of the most downfield signal of 1-bromopropane?
triplet
What is resonance?
What kind of solvents are used for NMR?
What is the TMS?
Alpha spin state flipping to beta spin state, energy is absorbed
Deuterated solvent or solvents with even number of protons/neutrons
TMS: Trimethylsilane, the 'control' for NMR. Makes a base peak at 0
How many signals are in 1-chloro-heptan-4-ol
How to find signals of alkenes? (ethylene)
Are these protons equivalent?
8
Find how groups correspond in cis and trans, are they seeing the same neighbors?
no, chiral center present in molecule (shortcut!)
Chemical shift of a benzene with acyl chloride and ethyl groups para.
4 signals
downfield is closet to acyl chloride and methyl carbon on ethyl group is most upfield
Interpretive dance showing integration
slay
What is the splitting of the most downfield carbon on acetic acid?
singlet (hydrogen on OH)