C2 2020

Question 1

Test for an ester?

Answer 1

Sweet smelling

Question 2

Why would it be appropriate to reweigh empty boat

Answer 2

To calculate exact mass of salicyclic added to reaction

Question 3

Explain purpose of adding small amount of cold ethanol

Answer 3

To remove insoluble impurities

Question 4

Explain polarity of the C-Br bond

Answer 4

Br is more electronegative than C
Delta - Br and Delta + C

Question 5

C=O to OH mechanism reagent?

Answer 5

NaBH4

Question 6

State why Si(CH3)4, CCl4 and CDCL3 are used in 1H NMR spectroscopy

Answer 6

Stage 1:
1a CDCl3 or CCl4 solvent
1b TMS as standard / peak
at 0
1c Inert

Stage 2 CCl4 or CDCl3 as solvent:
2a (Both) have no H tied to either CDCl3 or CCl4
2b CCl4 non polar
2c CDCl3 polar covalent molecule

Stage 3 TMS as reference:
3a give one single environment
3b Signal in an area away from other typical H peak upfield from others / signal in far right
3c Easy to remove / volatile / low bp

Question 7

WHy is CH3CHO slower than ClCH2CH-

Answer 7

C in C=O less delta + because CH3 attacthed is electron donating
Higher Ea