Mass Spectrometry

Question 1

Alcohols

Answer 1

Has no molecular ion peak because the molecular ion readily fragments and usually doesn’t reach the collector to record the fragment’s molecular mass.

Question 2

Ketones

Answer 2

Has an intense molecular ion peak. Breaks homolytically at the C-C bond and heterolytically at the C-O bond.

Question 3

Alkyl Halides

Answer 3

The C-Br bond is most apt to break (heterolytically) because it is the weakest.

Question 4

Bond Dissociation Energy

Answer 4

C-Br = 71 kcal/mol
C-Cl = 85 kcal/mol
C-C = 89 kcal/mol
C-H = 99 kcal/mol

Question 5

Ethers

Answer 5

The C-O bond is cleaved heterolytically while the C-C bond is cleaved homolytically. The most stable radical will want to form.