Chapter 32 (Structure Determination) Flashcards
1
Q
What factors influence choice of pathway?
A
- Availability/cost of starting materials
- Number of stages needed to convert target molecule
- If more than one product formed/purification needed
- Number and cost of separation
- Percentage yield expected
- Atom economy of overall process
- Amount of waste generated
- If toxic chemicals needed
2
Q
Why is TMS used to calibrate spectra?
A
- Gives one signal
- Non-toxic and inert
- Has low boiling point
- Gives signal that is far to the right of signals of organic compounds
3
Q
What is shown on a Proton NMR?
A
- Number of signals: How many different sets of equivalent H atoms there are
- Positions of the signals: Suggests environment that H atom is found
- Relative intensity: How many H atoms are found in that environment
4
Q
What affects the chemical shift of the absorbance in H NMR?
A
- The closer the H is to electronegative atoms, the greater the shift
- The more electronegative atoms the greater the shift
5
Q
What does splitting in H NMR show?
A
Provides information about the number of H atoms on the adjacent carbon.
singlet = no H on next carbon
doublet = 1 H on next carbon
triplet = 2 H on next carbon
quartet = 3 H on next carbon
6
Q
How is absorbance strength found for H NMR?
A
Area under each peak