Partial synthesis

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A partial synthesis , also called semisynthesis or partial synthesis , is understood in organic chemistry as a combination of chemical and biochemical synthesis processes. A further distinction can be made between the synthesis of an intermediate product, which leads to a target compound via an already known synthesis route, or the transfer of a complex compound, usually a natural substance - isolated from natural material (e.g. bacteria , fungi , plants or cell cultures ). as a starting material (starting material) to a target compound. These natural biomolecules often have a complex molecular structure. Such complicated structures are totally synthetic , starting from inexpensive mostly petrochemical starting materials, not accessible or only accessible with considerable effort and over many synthesis steps.

Example: partial synthesis of diacetylmorphine

  • 1. Growth of a poppy plant

  • 2. Obtaining the milky sap of a poppy plant

  • 3. Isolation of the morphine from the milk juice

  • 4. Acetylation of morphine to diacetylmorphine

  • 5. The end product heroin (= diacetylmorphine)

Intentions

With the help of partial synthesis, different variants of complex molecules can be produced in a simple process. The semisynthetically modified molecules can thus have better biological activity or even greater stability. Since the resulting molecules are mostly used in pharmacy, optimization of solubility, bioavailability or metabolism can be advantageous. In addition, partial synthesis can be used if the actual producer cannot obtain the natural product in sufficient quantities. This is the case, for example, with the production of paclitaxel in cancer therapy. Only 0.01-0.33% of this drug is found in the bark of the Pacific yew tree , but larger amounts are required for treatment.

Partial synthesis in antibiotics

Semi-synthetically produced substances sometimes outperform natural substances in terms of effectiveness, safety or stability, e.g. B. in the manufacture of pharmaceuticals . Naturally occurring cephalosporins have too little antibiotic effect, so enzymatic saponification is used to produce C 7-aminocephalosporanic acid (7-ACA for short) from cephalosporin , from which the more effective semisynthetic antibiotics cefaloridin, ceflexotin and cefalotin are then produced by partial synthesis ( acylation of the amino function ) Cefrodin are manufactured.

Not only cephalosporins are produced with the help of semisynthesis, but also other antibiotics such as amoxicillin . Its representation is similar to that of cephalosporins, since 6-aminopenicillic acid (6-APA for short) is produced from penicillin G , from which the semi-synthetic amoxicillin is then obtained by partial synthesis.

Other semisynthetically obtained antibiotics are, for example:

Painkiller

Some pain relievers such as heroin and codeine are also made semi-synthetically. Morphine is obtained from the extract of various Papaver species. The morphine obtained in this way is then processed semisynthetically into the morphine derivatives heroin and codeine. Other semisynthetically produced opioids for the treatment of pain are hydromorphone , buprenorphine , hydrocodone and oxycodone .

  • heroin

  • Codeine

  • Hydromorphone

  • Buprenorphine

  • Hydrocodone

  • Oxycodone

  • ASS

The well-known pain reliever acetylsalicylic acid (ASA) can be produced semisynthetically from the extract of willow bark (contains salicylic acid). However, since salicylic acid is produced technically from phenol by chemical synthesis, the semisynthesis of acetylsalicylic acid is of no practical importance.

literature

  • Hans-Dieter Arndt, Christian Hackenberger, Dirk Schwarzer: Semisynthesis, 1,2 , Chemistry in our time , Volume 44, 2010, Part 1: Chemistry with the molecules of nature , pp. 130-137, Part 2: Tools for chemistry Biology , pp. 198-206.

Individual evidence

  1. ↑ a b c d Hans-Dieter Arndt, Christian Hackenberger, Dirk Schwarzer: Semisynthesis. Chemistry with the molecules of nature . In: Chemistry in Our Time . tape 44 , no. 2 , 2010, p. 130-137 , doi : 10.1002 / ciuz.201000499 .
  2. ↑ Entry on semisynthesis. In: Römpp Online . Georg Thieme Verlag, accessed on June 4, 2020.
  3. ^ Ernst Mutschler : drug effects , Wissenschaftliche Verlagsgesellschaft Stuttgart, 3rd edition, 1975, ISBN 3-8047-0504-9 , pp. 421-422.
  4. ↑ Eberhard Klaschik : Pain therapy and symptom control in palliative medicine. In: Stein Husebø , Eberhard Klaschik (ed.): Palliative medicine. 5th edition, Springer, Heidelberg 2009, ISBN 3-642-01548-4 , pp. 207-313, here: pp. 232-233.