3.3.14/5/6 Organic synthesis, NMR and Chromatography

Question 1

Why are solvents not preferred when using organic synthesis to develop drugs?

Answer 1

they are flammable and toxic
and increase waste

Question 2

what are key factors that scientists consider when synthesising drugs

Answer 2

• yield
• process steps / efficiency
• toxicity of reagents
• waste

Question 3

what is NMR (nuclear magnetic resonance) used for

Answer 3

to help determine structure of molecule

Question 4

what are the 2 types of NMR

Answer 4

13C NMR - tells info on how carbon atoms are arranged

1H NMR - tells information on how hydrogen atoms are arranged

Question 5

How do NMR’s work?

Answer 5

• when atomic nucleus has odd number of nucleons it has NUCLEAR SPIN
• nuclear spin makes weak magnetic field
• NMR detects how these magnetic field are affected by a larger external magnetic field

Question 6

why does the NMR only detect carbon 13

Answer 6

because it can only detect molecules with a nuclear spin and for this spin you must have an odd number of nucleons

besides carbon 13, other variations of carbon e.g carbon 12 have even number of nucleons ( 6 protons, 6 neutrons)

so only 13 C (7 neutrons 6 protons) has nuclear spin and can be detected

(only 1% of carbons are 13 C)