Karl Ziegler

from Wikipedia, the free encyclopedia
Karl Ziegler

Karl Waldemar Ziegler (born November 26, 1898 in Helsa near Kassel , † August 11, 1973 in Mülheim an der Ruhr ) was a German chemist . His scientific life's work includes contributions to the chemistry of carbon radicals , organolithium compounds and ring closure reactions , to natural product chemistry and organometallic chemistry , to useful organic synthesis methods such as Wohl-Ziegler bromination and to an understanding of living polymerization . His work on the reaction of triethylaluminum with ethene led to the production of fatty alcohols for biodegradable detergents and as a by- product to high-purity aluminum oxide , which is used in many different ways in the chemical industry.

Ziegler, who headed the Max Planck Institute for Coal Research in Mülheim an der Ruhr for twenty-five years , created the basis for the mass production of plastics such as polyethylene and polypropylene with the Ziegler-Natta process for the production of polyolefins via coordinative insertion polymerization with organometallic catalysts . It was thanks to the invention of the process that Ziegler was awarded the Nobel Prize for Chemistry in 1963, which he and Giulio Natta were awarded for their discoveries in the field of chemistry and technology of high polymers . Based on his patents , several million tons of polyolefins are produced every year. On his 70th birthday, Ziegler donated 40 million German marks to a research fund from the proceeds of his licenses . Her honorary citizen Ziegler and his wife Maria bequeathed an important collection of 20th century paintings to the city ​​of Mülheim .

Ziegler was a co-founder in 1946 and was the first president of the Society of German Chemists (GDCh) until 1951 . It awards the Karl Ziegler Prize named after him and the Karl Ziegler Prize. Numerous industrial chemists and later professors such as Günther Otto Schenck , Günther Wilke and Klaus Hafner emerged from his scientific school .


Karl Ziegler was born as the second son of the couple Carl August and Luise Ziegler in Helsa near Kassel, where he spent his childhood and early youth. He attended elementary school in Kassel-Bettenhausen . In 1910 the family moved to Marburg , where the father worked as a Protestant pastor. From 1910 onwards, Ziegler attended the secondary school, the Martin Luther School . Reading an introductory textbook on physics and making contact with professors at the University of Marburg encouraged Ziegler's interest in science. From 1916 studied Ziegler chemistry at the University of Marburg, where he worked in the laboratory of Charles of Auwers his dissertation on the subject of investigations into semi benzenes and related compounds Customized and in August 1920 doctorate was. In March 1922 he married Maria Kurtz. The children Marianne and Erhart were from the marriage. As early as 1923 he completed his habilitation in Marburg with the text On the knowledge of “trivalent” carbon: About tetra-aryl-allyl radicals and their descendants. After completing his habilitation, there was a temporary teaching position with Julius von Braun in Frankfurt am Main from 1925 to 1926 . In 1926 he accepted a position as a private lecturer at Karl Freudenberg in Heidelberg .

After the seizure of power , Ziegler was denounced in 1934 by functionaries of the Heidelberg NSDAP local group for demonstratively dealing with a Jewish family at the Ministry of Culture. Ziegler's negative attitude towards National Socialism prevented an appointment to the University of Karlsruhe in 1936 , although a report by the Nazi educational scientist Ernst Krieck was positive and described him as a capable chemist with a talent for invention and discovery. It would therefore be a necessity to maintain and promote it, despite the strong political misgivings that exist against it.

The appointment was contradicted by the Karlsruhe lecturer association leader Helmut Weigel, who feared that “[…] he might one day be denounced as jointly responsible for the appointment of a fellow Jew” and asked that “a compromise between the person and the specialist Ziegler not be made our university to apply. As you wrote, it would really be the best if Z. could be put in a research institute. "

In the winter semester of 1935/36 Ziegler gave a guest lecture at the University of Chicago . After his return, the rector of Halle University , Emil Woermann , spoke out in favor of the chemist's move to Halle , despite Ziegler's disputes with the NSDAP in Heidelberg . The Reich Minister of Education, Bernhard Rust , ordered the relocation and assumption of the chair there as full professor and director of the Chemical Institute on October 1, 1936. Ziegler was a supporting member of the SS and received the War Merit Cross 2nd Class on October 19, 1940 .

Kaiser Wilhelm Institute for Coal Research
(today: Max Planck Institute for Coal Research )

In order to limit its influence on students, the Reich Ministry of Education took up Weigel's idea in 1943, and Rudolf Mentzel advocated his transfer to a research institute. In 1943 Ziegler succeeded Franz Fischer as director of the Kaiser Wilhelm Institute for Coal Research in Mülheim (Ruhr). Ziegler was initially skeptical of this appointment, as his scientific work had hardly anything to do with coal research until his appointment. The foundation of the Kaiser Wilhelm Society gave him complete freedom in the choice of research areas. In 1945 US troops occupied the institute and temporarily subordinated it to the North German Coal Control , mainly because of Franz Fischer's work on the Fischer-Tropsch process . The institute in Mülheim was renamed the Max Planck Institute for Coal Research in 1948 . From 1949 Ziegler taught as an honorary professor at RWTH Aachen University . From 1953 in Mülheim he developed a low pressure polymerization process for ethene in the presence of organometallic mixed catalysts .

From September 20, 1949 to December 31, 1951, he was the first chairman of the Gesellschaft Deutscher Chemiker (GDCh) that emerged from the merger of regional societies . Before that he was from September 20, 1946 to September 20, 1949 founding chairman of the GDCh in the British zone . In 1952 he gave guest lectures at the University of Wisconsin-Madison and the University of Illinois at Urbana-Champaign . In 1954 he took over the chairmanship of the German Society for Mineral Oil Science and Coal Chemistry and one year later he became chairman of the chemical-physical-technical section and senator of the Max Planck Society . He held both positions until 1957.

Ziegler described his life's work in 1966 with the following words: “I started like the hiker who penetrates an unknown country and who probably suspects that there may be a lot of beautiful and interesting things ahead of him, who can now and then overlook part of the way who, however, does not know where the journey will ultimately lead. "

In 1969 he retired in Mülheim an der Ruhr. Between 1970 and 1971 Ziegler was the founding president of the Rheinisch-Westfälische Akademie der Wissenschaften in Düsseldorf .

On August 11, 1973, Karl Ziegler died of a heart attack at the age of 74 in Mülheim an der Ruhr, where he was buried in the main cemetery.

Scientific major work

Overview of Ziegler's main scientific work (based on his Nobel Lecture)

Ziegler's academic studies began in Karl von Auwers' group with work on semibenzenes (methylenecyclohexadienes). After receiving his doctorate, Ziegler began studying carbon radicals on the advice of Auwers. These studies led on the alkaline organic compounds and aluminum organic compounds in the discovery of organometallic mixed catalysts and the production of polyolefins .

In addition, Ziegler repeatedly carried out successful research in other areas of organic chemistry that led to the preparation of large carbon rings, the synthesis of natural products, the synthesis of azulene and preparative methods such as Wohl-Ziegler bromination .

Free radicals

1,1,3,3-tetraphenylallyl radical (Ziegler, 1923)

During his time as a doctoral student at the University of Marburg , Ziegler was interested in substituted ethane derivatives and the formation of organic radicals . In his first scientific publication he showed how halochromic (R 3 C + Z - ) salts can be prepared from carbinols . Earlier work had given the impression that halochromic salts or free radicals of the type (R 3 C •) would require an aromatic radical for stabilization. He was asked to synthesize similarly substituted radicals, and in 1923 he successfully produced the 1,1,3,3-tetraphenylallyl and pentaphenylcyclopentadienyl radicals. Both of these compounds were more stable than previously synthesized carbon free radicals, such as the triphenylmethyl radical.

Over the years Ziegler has published many papers in which he described the steric and electronic factors for the dissociation of hexasubstituted ethane derivatives . His interest in the stability of trivalent carbon radicals was recognized in 1935 when he was awarded the Liebig Medal by the then Association of German Chemists for research in the field of radicals with trivalent carbon and for excellently thought-out and reliably worked out syntheses of multi-membered ring systems .

Organic alkali compounds

To investigate the 1,1,3,3-tetraphenylallyl radical, Ziegler tried to reduce the allylic double bond using a method by Wilhelm Schlenk with metallic potassium . Since the radical itself was not amenable to reduction, he took this on a precursor of the radical, the 1,1,3,3-tetraphenylallyl ethyl ether. As a result, he did not receive the expected reduced product, but rather highly reactive potassium alkyls were formed through ether cleavage in addition to alcoholates . Ziegler extended his research in the field of alkali alkyls to include organo sodium and organolithium compounds . With the conversion of alkyl chlorides with metallic lithium , Ziegler developed a general and simple process for the production of organolithium compounds, such as butyllithium from 1-chlorobutane and lithium. This made organic lithium compounds universally applicable reagents in organic synthesis.

In 1927, Ziegler found that the addition of phenylisopropylpotassium to a solution of stilbene (1,2-diphenylethene) in diethyl ether resulted in a color change from red to yellow. As Ziegler was able to show, the color change was based on the insertion reaction of the stilbene double bond into the potassium-carbon bond with the formation of a new carbon-potassium bond. With this, Ziegler had discovered another fundamental reaction in organometallic chemistry.

Living polymerization

Manufacture of synthetic rubber at Bayer

Ziegler recognized that the mechanism found when studying the insertion of stilbene can easily be transferred to the polymerization of butadiene with sodium. Around 1930 he and his colleague Colonius developed a method for investigating the polymerization process in the production of synthetic rubber from 1,3-butadiene using elemental sodium ( Buna ). It was possible to prove that it is an anionic polymerisation which proceeded analogously to the previously observed insertion of the stilbene addition to phenylisopropylpotassium and is referred to as living polymerisation for which no termination reaction exists.

Organometallic compounds

The research on organolithium compounds finally led Ziegler to organoaluminum chemistry. While investigating the reaction of lithium aluminum hydride with ethene, Ziegler came across α - olefins . It turned out that organoaluminum compounds were even more effective in this reaction. From 1949 onwards, Ziegler and Gellert investigated the reaction of triethylaluminum with ethene at higher temperatures. Long chain aluminum alkyls occurred in this reaction. A maximum of about 100 ethene units were deposited per chain. The distribution of the chain length corresponded to a Poisson distribution , which could be optimized for the range from 10 to 16 carbons by suitable choice of the process parameters.

Even-numbered α-olefins were formed by an elimination reaction . The successful with them alkylation of benzene to linear alkyl benzenes . After sulphonation and neutralization, these were suitable as anionic surfactants and, compared to the tetrapropylene benzene sulphonates used since the 1950s , which led to foam formation and a lack of oxygen in water, were readily biodegradable .

During the oxidation of the aluminum alkyl complex with oxygen and subsequent hydrolysis with sulfuric acid and water, nature-identical fatty alcohols , so-called Ziegler alcohols or alfoles, are formed, which are used as fatty alcohol sulfates or, after ethoxylation and sulfation, as alkyl ether sulfates in personal care products and detergents and cleaning agents. According to the detergents law passed in 1961, detergents and cleaning agents were only allowed to contain surfactants that are at least 80% biodegradable. This criterion is also valid in the current legal situation through the detergents regulation (regulation (EC) No. 648/2004 on detergents). The Ziegler alcohols are unbranched and even, the anionic surfactants made from them are readily biodegradable.

Soon afterwards, Ziegler and co-workers investigated the conversion of tripropylaluminum with propene and obtained 2-methylpent-1-ene . This process became the basis for the manufacture of isoprene according to the Goodyear Scientific Design process.

Ziegler catalysts

Scheme of the HDPE (high density polyethylene) and LLDPE - (linear low-density polyethylene) method

Between 1952 and 1953, Ziegler and Hans-Georg Gellert found that when attempting to polymerize ethene with organolithium compounds, the compounds break down into lithium hydride and the olefin. The only exception was lithium aluminum hydride . To research whether lithium or aluminum was the more active material, Gellert tested various organoaluminum components. Triethylaluminum added some ethene molecules, but the carbon chain distribution differed due to competing chain termination reactions. When attempting to react isopropyl aluminum and ethene in a stainless steel autoclave at 100 to 200 bar and 100 ° C, Ziegler and Holzkamp received only 1-butene . Further investigation led to the conclusion that the autoclave contained traces of nickel which had stopped the polymerization. Holzkamp demonstrated this so-called nickel effect by adding nickel salts to the reaction mixture.

Nickel was thus the first Ziegler catalyst. It became possible to dimerize ethene under very mild conditions. After the reason for the termination reaction was recognized, Ziegler looked for ways to suppress it. His staff tested a number of metal salts. The most effective Ziegler catalysts are based on titanium and zirconium compounds in combination with organoaluminum compounds. The titanium salts in particular were so reactive that the reaction pressure and the reaction temperature could finally be lowered to normal pressure and room temperature. The use of titanium (IV) chloride with triethylaluminum resulted in high polymer products under mild conditions. Before, this was only possible under enormous pressures of 1000 to 2000 bar and temperatures of 200 ° C in the ICI process.

The discovery was a tremendous success. The polyethylene produced according to the Ziegler process was not only stiffer, but also more resistant to higher temperatures. Copolymerization with α-olefins allows the properties of the material to be tailored for specific applications. Many other olefins such as propene, 1,3-butadiene or isoprene could be polymerized with the Ziegler catalysts. The transition to large-scale production took place very quickly. In 1955 only 200 tons were produced, in 1958 17,000 tons and in 1962 120,000 tons of low-pressure polyethylene. In 2003, 50 years after the discovery of Ziegler catalysts and low-pressure olefin polymerization, around 25 to 30 million tons of polypropylene, 10 to 12 million tons of high-pressure polyethylene and about 15,000 tons of aluminum alkyls were produced according to Ziegler's patents.

The patent applications by Ziegler in 1953 and shortly afterwards by Guillio Natta and Montecatini were followed by decades of legal disputes over patent rights , especially claims relating to the copolymerization of ethene with α-olefins such as propene and 1-butene and the production of polypropylene . In January 1953, Ziegler and the Italian chemical company had signed contracts for the technical utilization of organoaluminum reactions. They included the subsequent inventions and an exclusive license for Italy for certain property rights. In 1954, Ziegler passed on his information on the new catalytic converters to Montecatini and asked for understanding that the expansion of the new catalytic converters should initially be entirely reserved for the Mülheim institute. In 1954, however, Montecatini and Giulio Natta applied for a patent for the production of polypropylene using catalysts made from triethylaluminum and titanium chloride. The patent applications ended in a patent dispute that dragged on between the Max Planck Institute and Montecatini for several decades, especially before US courts. The US Patent Office eventually gave Ziegler priority. In 1983 the parties reached a settlement. Montecatini waived all claims and paid damages to the Max Planck Institute.

Further research areas

In addition to his work on organometallic chemistry and catalysis , Ziegler carried out research in the field of natural product chemistry and preparative organic chemistry. Its name is linked to the synthesis of large carbon rings , which among other things led to the synthesis of the ingredients in musk oil .

Multi-membered carbon rings

In 1933, Ziegler, Eberle and Ohlinger published their first work - based on research by Ruggli around 1920 - on the production of multi-membered carbon rings. Ring formations were carried out with α, ω-di nitriles with lithium diethylamide as the base. In doing so, Ziegler relied on a strong dilution of the dinitriles in the solution, so that the intermolecular chain formation was made more difficult. The Ziegler-Ruggli dilution principle enabled the preparation of carbon rings with 14–30 carbon atoms in good yield.

Work on heating 1,3-butadiene to 200 ° C. had shown that 1,5-cyclooctadiene was easily formed in yields of up to 15%. With ethene and butadiene and the Ziegler catalyst, rings with 8, 10, 12 carbon atoms, such as cyclooctadiene, cyclodecadiene and cyclododecatriene , which can hardly be produced by other methods, could be produced .

Synthesis of cantharidin and ascaridol

Structure of cantharidine

After Ziegler had already successfully produced a racemate of the natural product muscone using his method for producing large rings , he continued research in the field of natural product chemistry, which led to the synthesis of cantharidin , a terpenoid found in various species of beetle and an ingredient of the Spanish fly .

In Halle, Günther Otto Schenck and Ziegler succeeded in synthesizing ascaridol , at that time the only natural product identified with a peroxide function . Ascaridol is synthesized from pinene and oxygen in the presence of chlorophyll and is regarded as a textbook example for photooxidation with sensitization with chlorophyll .

Bromination in the allyl position

Ziegler developed the bromination with N- bromoacetamide , introduced by Alfred Wohl , into the Wohl-Ziegler reaction , a bromination in the allyl position using N- bromo succinimide and a radical initiator. The process is now a standard method in preparative organic chemistry.

Azulene synthesis

Together with Klaus Hafner , Ziegler developed a versatile synthesis of azulene , represented by the condensation reaction of a cyclopentadienyl anion with an intermediate from the nucleophilic addition of dimethylamine to an activated pyridine derivative with ring opening , the so-called Koenig's salt . It is known as the Ziegler-Hafner synthesis .

Electrochemical investigations

From 1953, Ziegler researched the electrolytic deposition of aluminum and the electrochemical synthesis of metal alkyl compounds. From the liquid complex compounds of sodium fluoride with triethylaluminum, it was possible to separate highly pure aluminum . The basic process was later commercialized by Siemens in the SIGAL process.

The development of the electrochemical synthesis of metal alkyls such as diethylmercury and tetraethyl lead also fell during this period . Although tetraethyl lead was used in large quantities as a fuel additive, Ziegler stopped investigations in the early 1970s due to difficulties in process development and the development of three-way catalytic converters that required unleaded gasoline.

Art collection

From 1958 Ziegler and his wife Maria began to build up a collection on the art of expressionism and classical modernism. The first pictures came from painters such as Erich Heckel , Karl Hofer , Franz Marc and Emil Nolde . Ziegler, who was largely financially independent due to the license income from his inventions, collected further works by August Macke , Max Beckmann and Lyonel Feininger over the next few decades . The Zieglers seldom sought advice on the selection of the pictures and did not make their selection based on art historical aspects. Often the choice of images concerned places with which there was an emotional connection.

The pictures are shown today in an exhibition at the Mülheim an der Ruhr Art Museum . They are the core of a collection that has been expanded by the Ziegler Collection Foundation , now includes 115 works and is one of the most important collections in the region. In 2019 the collection was exhibited in the Moritzburg Art Museum in Halle (Saale) and then in Emden .


Memorial plaque of the GDCh

Numerous scientific societies around the world recognized Ziegler for his scientific work. In 1935 he received the Liebig memorial coin and in 1953 the Carl Duisberg plaque from the Association of German Chemists. In 1938 he was elected a member of the Leopoldina . The Lavoisier Medal of the Société Chimique de France received Ziegler in 1955 and three years later, in 1958, Ziegler was with Carl Engler Medal of the German Scientific Society for Petroleum and coal e. V. excellent.

In 1960, together with Otto Bayer and Walter Reppe , he was awarded the Werner von Siemens Ring by the Werner von Siemens Foundation in recognition of their work on expanding the scientific basis and the technical development of new synthetic, high-molecular materials . The Technical University of Hanover , the University of Gießen , the University of Heidelberg and the Technical University of Darmstadt awarded him an honorary doctorate .

For his discovery of the Ziegler-Natta process for the production of polyolefins via coordinative insertion polymerization with organometallic catalysts, Ziegler received the Nobel Prize in Chemistry in 1963, together with the Italian chemist Natta .

He also received the Swinburne Medal from The Plastics Institute, London, in 1964 , and in the same year the Great Federal Cross of Merit with Star and Shoulder Ribbon of the Federal Republic of Germany .

Further awards were in 1967 the International Synthetic Rubber Medal by Rubber and Plastics Age and in 1969 the Order Pour le Mérite for Sciences and Arts (formerly Peace Class). In 1971 he was elected Foreign Member of the Royal Society .

In 2008, the memorial plaque of the Society of German Chemists was unveiled in the context of the Historical Sites of Chemistry program on the old building of the Max Planck Institute for Coal Research in Mülheim an der Ruhr.

A grammar school in Mülheim, the Karl Ziegler School , was named after Ziegler . In the German Chemical Society named after him Karl Ziegler Foundation is located, which is endowed with 50,000 euros Science Award Karl Ziegler Prize awards and the Karl Ziegler Prize.


  • Günther Wilke : The portrait: Karl Ziegler 70 years. In: Chemistry in Our Time. 2, 1968, pp. 194-200, doi : 10.1002 / ciuz.19680020605 .
  • Kurt Unbehau: The honorary citizens of the city of Mülheim an der Ruhr . Mülheim an der Ruhr, 1974, pp. 80-84.
  • Heinz Martin: Polymers & Patents - Karl Ziegler, the team, 1953–1998. Wiley-VCH, Weinheim 2001, ISBN 978-3-527-30498-1 .
  • Matthias W. Haenel: Historic sites of chemistry: Karl Ziegler. Max Planck Institute for Coal Research, Mülheim 2009. PDF; 3.1 MB .
  • Manfred Rasch : Karl Ziegler - Nobel laureate in chemistry, institute director and science manager. In: Horst A. Wessel (Ed.): Mülheim entrepreneurs and pioneers in the 19th and 20th centuries. Klartext Verlag, Essen 2012, pp. 328–337.

Web links

Commons : Karl Ziegler  - Collection of images, videos and audio files

Individual evidence

  1. ^ Karl Ziegler - Entry in Encyclopedia Britannica. Retrieved June 23, 2013 .
  2. ^ Karl Ziegler - Biographical. Retrieved August 1, 2013 .
  3. Karl Ziegler: On the knowledge of "trivalent" carbon: About tetra-aryl-allyl radicals and their descendants . Dissertation, Verlag Chemie, 1924.
  4. ^ Ziegler, Karl (1898–1973), chemist. Retrieved August 26, 2013 .
  5. a b c d e Bernhard vom Brocke and Hubert Laitko (ed.): The Kaiser Wilhelm, Max Planck Society and their institutes. The Harnack Principle . Verlag de Gruyter, Berlin 1996, ISBN 3-11-015483-8 , pp. 484f.
  6. Henrik Eberle: The Martin Luther University in the time of National Socialism. Mdv, Halle 2002, ISBN 3-89812-150-X , p. 450 and p. 448.
  7. ^ Ernst Klee : The dictionary of persons on the Third Reich. Who was what before and after 1945 . Fischer Taschenbuch Verlag, 2nd updated edition, Frankfurt am Main 2005, ISBN 978-3-596-16048-8 , p. 694 with reference to Henrik Eberle: The Martin Luther University [Halle] in the time of National Socialism 1933– 1945, hall 2002 .
  8. a b c d e f Günther Wilke : The portrait: Karl Ziegler 70 years. In: Chemistry in Our Time. 2, 1968, pp. 194-200, doi : 10.1002 / ciuz.19680020605 .
  9. ^ Max Planck Institute for Coal Research - History. Retrieved June 23, 2013 .
  10. a b c d e f Historic sites of chemistry - Karl Ziegler. (PDF; 2.0 MB) Retrieved August 2, 2013 .
  11. ^ Günther Wilke : Development of an Invention , In: North Rhine-Westphalia Academy of Sciences, Symposium "50 Years of Ziegler Catalysts". Lectures N 463, Verlag Ferdinand Schöningh GmbH & Co KG, 2004, ISBN 3-506-73519-5 , p. 5.
  12. ^ City of Mülheim-Ruhr - Karl Ziegler (1898–1973). Retrieved June 23, 2013 .
  13. ^ A b c Karl Ziegler: Consequences and career of an invention Nobel lecture on December 12, 1963. In: Angewandte Chemie. 76, 1964, pp. 545-553, doi : 10.1002 / anie.19640761302 .
  14. ^ Karl Friedrich von Auwers, Karl Ziegler: About hydrocarbons of the semibenzene group. In: Justus Liebig's Annals of Chemistry. 425, 1921, pp. 217-280, doi : 10.1002 / jlac.19214250302 .
  15. Karl Ziegler: On the knowledge of the "trivalent" carbon. I. About tetra-aryl-allyl radicals and their derivatives. In: Justus Liebig's Annals of Chemistry. 434, 1923, pp. 34-78, doi : 10.1002 / jlac.19234340104 .
  16. Karl Ziegler: 25 years "On the knowledge of 'trivalent' carbon" In: Angewandte Chemie. 61, 1949, pp. 168-179, doi : 10.1002 / anie.19490610503 .
  17. ^ Wilhelm Schlenk, Ernst Bergmann: Research in the field of organic alkali compounds. I. About products of the addition of alkali metal to multiple carbon-carbon bonds. In: Justus Liebig's Annals of Chemistry. 463, 1928, pp. 1-97, doi : 10.1002 / jlac.19284630102 .
  18. Karl Ziegler, Berthold Schnell: On the knowledge of the "trivalent" carbon: II. The conversion of ethers of tertiary alcohols into organic potassium compounds and six-substituted ethane derivatives. In: Justus Liebig's Annals of Chemistry. 437, 1924, pp. 227-255, doi : 10.1002 / jlac.19244370114 .
  19. Karl Ziegler, Helmut Dislich: Metallorganischeverbindungen , XXIII. About α-phenyl-isopropyl-potassium. In: Chemical Reports. 90, 1957, pp. 1107-1115, doi : 10.1002 / cber.19570900634 .
  20. ^ Karl Ziegler, Herbert Colonius: Investigations on alkali-organic compounds. V. A Convenient Synthesis of Simple Lithium Alkyls . In: Justus Liebig's Annals of Chemistry. 479 (1930) pp. 135-149, doi : 10.1002 / jlac.19304790111 .
  21. ^ Zvi Z. Rappoport, Ilan Marek: The Chemistry of Organolithium Compounds , John Wiley & Sons (2004), 1400 pages, ISBN 0-470-84339-X .
  22. Karl Ziegler, F. Crössmann, H. Little, O. Shepherd: Studies on alkali-organic compounds. I. Reactions between unsaturated hydrocarbons and alkali metal alkylene. In: Justus Liebig's Annals of Chemistry. 473, 1929, pp. 1-35, doi : 10.1002 / jlac.19294730102 .
  23. Karl Ziegler, Kurt Bähr: About the presumed mechanism of polymerizations by alkali metals (preliminary communication). In: Reports of the German Chemical Society (A and B Series). 61, 1928, pp. 253-263, doi : 10.1002 / cber.19280610203 .
  24. ^ Günther Wilke: Karl Ziegler - The Last Alchemist. In: Gerhard Fink, Rolf Mülhaupt, Hans H. Brintzinger: Ziegler Catalysts , pp. 1-14, 511 pages, Verlag Springer (1995), ISBN 3-540-58225-8 .
  25. Entry on olefins . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.O04281 Version: 2.3.3.
  26. Carlo Perego, Patrizia Ingallina: Recent advances in the industrial alkylation of aromatics: new catalysts and new processes. In: Catalysis Today . 73, 2002, pp. 3-22, doi : 10.1016 / S0920-5861 (01) 00511-9 .
  27. a b c Walter Hagge: Modern developments and economic importance of detergents. In: fats, soaps, paints. 67, 1965, pp. 205-211, doi : 10.1002 / lipi.19650670312 .
  28. Gunther Czichocki, Helga Brämer, Inge Ohme: Production, properties and analysis of ether sulfates. In: Journal of Chemistry. 20, 1980, pp. 90-94, doi : 10.1002 / zfch.19800200303 .
  29. Law on detergents in detergents and cleaning agents ( Federal Law Gazette I p. 1653 )
  30. Regulation (EC) No. 648/2004 of the European Parliament and of the Council of March 31, 2004 on detergents , accessed on August 17, 2013
  31. ^ Karl Ziegler: Aluminum-organic synthesis in the field of olefinic hydrocarbons. In: Angewandte Chemie. 64, 1952, pp. 323-329, doi : 10.1002 / anie.19520641202 .
  32. Karl Fischer, Klaus Jonas, Peter Misbach, Reinhold Stabba, Günther Wilke: On the "nickel effect". In: Angewandte Chemie. 85, 1973, pp. 1001-1012, doi : 10.1002 / anie.19730852302 .
  33. Karl Ziegler, Erhard Holzkamp, ​​Heinz Breil, Heinz Martin: Polymerization of ethylene and other olefins. In: Angewandte Chemie. 67, 1955, pp. 426-426, doi : 10.1002 / anie.19550671610 .
  34. ^ Günther Wilke: 50 Years of Ziegler Catalysts: Career and Consequences of an Invention. In: Angewandte Chemie. 115, 2003, pp. 5150-5159, doi : 10.1002 / anie.200330056 .
  35. Heinz Martin: Polymers, Patents, Profits: A Classic Case Study for Patent Infighting , 294 pages, Wiley-VCH Verlag GmbH & Co. KGaA (2007), ISBN 3-527-31809-7 .
  36. a b Patent solution from the mason jar. (PDF; 421 kB) Accessed July 1, 2013 .
  37. Karl Ziegler, Helga Froitzheim-Kühlhorn: Ring size and activity of cyclic cis-olefins. In: Justus Liebig's Annals of Chemistry. 589, 1954, pp. 157-162, doi : 10.1002 / jlac.19545890204 .
  38. Karl Ziegler, K. Weber: On multi-membered ring systems: IV. The synthesis of rac. Muscons. In: Justus Liebig's Annals of Chemistry. 512, 1934, pp. 164-171, doi : 10.1002 / jlac.19345120114 .
  39. ^ Karl Ziegler, Günther Otto Schenck, EW Krockow: Synthesis of Cantharidins. In: The natural sciences. 29, 1941, pp. 390-391, doi : 10.1007 / BF01479894 .
  40. ^ Fritz Eiden: Cantharidin: wedding gift, protective and attractant, bladder puller and enzyme inhibitor. In: Chemistry in Our Time. 40, 2006, pp. 12-19, doi : 10.1002 / ciuz.200600354 .
  41. ^ Günther Otto Schenck, Karl Ziegler: The synthesis of Ascaridols. In: The natural sciences. 32, 1944, pp. 157-157, doi : 10.1007 / BF01467891 .
  42. A. Wohl: Bromination of unsaturated compounds with N-bromo-acetamide, a contribution to the theory of the course of chemical processes. In: Reports of the German Chemical Society (A and B Series). 52, 1919, pp. 51-63, doi : 10.1002 / cber.19190520109 .
  43. Karl Ziegler, A. Späth, E. Schaaf, W. Schumann, E. Winkelmann: The halogenation of unsaturated substances in the allyl position. In: Justus Liebig's Annals of Chemistry. 551, 1942, pp. 80-119, doi : 10.1002 / jlac.19425510103 .
  44. Jerry March: Advanced Organic Chemistry. 3rd edition, John Willey & Sons, 1985, p. 624, ISBN 0-471-85472-7 .
  45. ^ Karl Ziegler, Klaus Hafner: A rational synthesis of the azulene. In: Angewandte Chemie. 67, 1955, pp. 301-301, doi : 10.1002 / anie.19550671103 .
  46. ^ Karl Ziegler, Herbert Lehmkuhl: The electrolytic deposition of aluminum from organic complex compounds. In: Journal of Inorganic and General Chemistry. 283, 1956, pp. 414-424, doi : 10.1002 / zaac.19562830142 .
  47. Karl Ziegler, H. Lehmkuhl, E. Hüther, W. Grimme, W. Eisenbach, H. Dislich: The electrochemical synthesis of metal alkyls. In: Chemical Engineer Technology - CIT. 35, 1963, pp. 325-331, doi : 10.1002 / cite.330350502 .
  48. a b c Foundation / History: From the Ziegler Collection to the “Ziegler Collection Foundation”. Retrieved July 1, 2013 .
  49. Steffen Tost: Loan from the Mülheim Ziegler Collection is popular in Halle. Neue Ruhr-Zeitung from April 16, 2019, accessed on April 21, 2019
  50. ^ Member entry by Karl Ziegler at the German Academy of Natural Scientists Leopoldina , accessed on September 2, 2013.
  51. ^ Carl Engler Medal 1958 - Prof. Dr. Dr. hc Karl Ziegler. (PDF; 113 kB) (No longer available online.) Archived from the original on October 22, 2013 ; Retrieved June 21, 2013 .
  52. KARL ZIEGLER - Ringträger 1960. (No longer available online.) Archived from the original on October 14, 2013 ; Retrieved June 21, 2013 .
  53. Entry on Ziegler; Karl (1898-1973) in the Archives of the Royal Society , London
  54. Handover of the medal by the chancellor PERCY ERNST SCHRAMM to KARL ZIEGLER in Göttingen on June 13, 1969. (PDF; 24 kB) Retrieved on August 10, 2013 .
  55. ^ Program “Historic Sites of Chemistry” of the GDCh. Retrieved June 21, 2013 .
  56. ^ Karl Ziegler Foundation, Karl Ziegler Prize until 1992 at GDCh.de. (No longer available online.) Archived from the original on June 4, 2013 ; Retrieved June 16, 2013 .
  57. Caroline Zörlein: The Karl Ziegler Foundation. In: News from chemistry. 56, 2008, pp. 941-942, doi : 10.1002 / nadc.200860991 .

This article was added to the list of excellent articles on September 7, 2013 in this version .