Question

with the 15. (16 pts) Which of the following molecules are aromatic and which are not? Support your choices Hückel calculation, a Frost circle, and a few words of explanation in each case. spectrum. Then peak. Atomic 16. (9 pts) From the molecules shown below, choose the one that one matches the given mass explain your choice and draw the structure of the fragment that corresponds to the base masses (in a.m.u.) are as follows: C 12;H-10-16; F 19:CI- 35.45;Br -79.90. c) Br a) c MASS SPECTRUM 100 80 2 60 0 40 20- 0.0 0.0 120 80 m/z 160 40

Answer 1

15) all molecules are planar conjugated systems.

n: 오 bonds + posi

n=2 It
cuclooctatertraene usually stays in non planar structure and remanins non aromatic.
on Nihoen atom

16) base peak corresponds to mass a little more than 40. this implies the molecule can be CO₂ (12+16+16=44amu)

molecular ion peak comes very close to 140. since a CO₂ molecule should be liberated from the parent molecule, it should have a carboxylic acid group. Hence, the answer is option (d)

mass of molecule can also be calcluated to be (79.9+14+28+17=)139 which is in agreement with the spectra shown.