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OH
OCOCH 3
OCOCH 3
Ac 2 O
Ac 2 O
O
O
O
CH 3 -N
CH 3 -N
CH 3 -N
OH
OH
OCOCH 3
Morphine
3-Acetylmorphine
Heroin
FIGURE 8.3
Acetylation of morphine using acetic anhydride to generate heroin.
8.3 HOW MORPHINE WORKS IN THE BRAIN
Morphine is used as a powerful analgesic to relieve severe pain by acting directly
on the brain. It appears to mimic endorphins, natural substances produced by the
brain that are responsible for reducing pain but also cause sleepiness and feelings of
pleasure in the body. Morphine is classified as a narcotic, which is a drug that dulls
the senses. Although it has painkilling properties it also possesses both euphoric and
hallucinatory effects.
Morphine also can be chemically converted by an acetylation reaction using
acetic anhydride and pyridine to create a much more potent form of narcotic drug
known as heroin (Figure 8.3) (see Section 8.5).
8.4 CODEINE
Morphine is converted to another alkaloid with a similar skeleton known as codeine
(Figure 8.4) by chemical synthesis using an industrial methylation procedure. Thus,
codeine becomes by far the most commonly used opioid in the world. There are
several methods for converting codeine to morphine by demethylation (codeine is
morphine 3-methyl ether). One way is by the cleavage of aromatic ethers by reflux-
ing morphine with concentrated HBr or HI. To produce codeine in another direct
way, albeit with low yield, is to extract codeine from the opium, after separation of
the more abundant morphine. Usually, however, most codeine is synthesized from
morphine through an O-methylation reaction.
O
H 3 C
O
H
H
N
CH 3
HO
FIGURE 8.4 Chemical structure of a related alkaloid to morphine, codeine, where one of
the OH groups undergoes a methylation reaction.
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