Organic Chemistry

The new bonds are now on either side of the double bonds.

Erasing these bonds and putting a bond between the two carbons that were attached by

the bonds gives the diene and the dienophile.

Now continue on to Problem 19.

PROBLEM 19

What diene and what dienophile should be used to synthesize the following compounds?

a. c. e.

b. d. f.

8.9 Ultraviolet and Visible Spectroscopy

Spectroscopyis the study of the interaction between matter and electromagnetic
radiation—radiant energy that displays the properties of both particles and waves. Sev-
eral different spectrophotometric techniques are used to identify compounds. Each em-
ploys a different type of electromagnetic radiation. We will start here by looking at
ultraviolet and visible (UV/Vis) spectroscopy. We will look at infrared (IR) spectroscopy
in Chapter 13 and nuclear magnetic resonance (NMR) spectroscopy in Chapter 14.

COOH

COOH

O

O

O

CH

CH

O

COCH 3

COCH 3

O

O

CN

O

COCH 3

CH 3

s

s p

O

COCH 3

CH 3

new σ bond

new σ bond

s

O

COCH 3

CH 3

add a bond

add a bond

remove a bond

Section 8.9 Ultraviolet and Visible Spectroscopy 321