KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 1

Norges teknisk-naturvitenskapelige universitet

Trondheim

Institutt for kjemi

KJ 2022/TKJ 4115

Spectroscopic methods in organic

chemistry

Examination Friday June 2. 2006, 09.00-13.00

Permitted aids: Simple calculator, ruler. The examination consists of 7 pages. Contact during examination: Professor Thorleif Anthonsen, phone 73596206 or 91897167 Assosiate professor Elisabeth Jacobsen, phone 73594190 or 98843559

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 2

Exercise 1 ( 50 points)

• Find the structure of the compound who´s spectra are shown i Figure 1. • Discuss the spectra.

Figure 1

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 3

Exercise 2 (20 points)

• The IR and 1H NMR spectra for an unknown compound with the formula C9H10O are given in Figure 2. Find the structure.

• Explain the splitting pattern in the 1H NMR spectrum.

Figure 2

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 4

Exercise 3 (20 points) a)

• Interpret the COSY (1H-1H correlated) and HSQC (1H-13C correlated) spectra for 5-bromo-2-methyl-1-pentene which are shown in Figures 3a and 3b, respectively. (A peak at 143 ppm in the 13C spectrum is omitted).

Br

Figure 3a

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 5

HSQC

Figure 3b b)

• Figure 4 shows the mass spectrum of a secondary amine. Explain the peaks with m/z-values.

Figure 4

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 6

c) • Draw the ionic structures and annotate the five possible fragmentations a-e.

Exercise 4 (10 points) • The unsaturated ketones below have the following lmaks values: 254, 239, 324,

249, 244 og 407 nm. Assign the right lmaks value to the respective ketone by using Table 1.6 fra Williamson & Fleming (attached).

O

O O

O

O O

a b c

d e f • How would the lmaks values be affected when the solvent is changed from

ethanol to hexane?

KJ 2022/ TKJ 4115 Spectroscopic methods in organic chemistry, Examination June 2. 2006 7