Paul Friedländer (chemist)
Encyclopedia
Paul Friedländer was a German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 chemist
Chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 best known for his research on derivates of indigo
Indigo
Indigo is a color named after the purple dye derived from the plant Indigofera tinctoria and related species. The color is placed on the electromagnetic spectrum between about 420 and 450 nm in wavelength, placing it between blue and violet...

 (for example thioindigo
Thioindigo
Thioindigo is an organosulfur compound that is used for dying polyester fabrics. It is related to the more common dye indigo by replacement of two NH groups with sulfur atoms....

) and isolation of Tyrian purple
Tyrian purple
Tyrian purple , also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye, which is extracted from sea snails, and which was possibly first produced by the ancient Phoenicians...

 from Murex brandaris.

Life and work

Paul Friedländer was born as son of Ludwig Friedländer
Ludwig Friedländer
Ludwig Henrich Friedlaender was a German philologist.He studied at the universities of his hometown Königsberg, Leipzig, and Berlin from 1841 to 1845...

 in Königsberg in 1857. The chemist Carl Gräbe
Carl Gräbe
Carl Gräbe was a German chemist from Frankfurt am Main.Gräbe studied at a vocational high school in Frankfurt and Karlsruhe Polytechnic and in Heidelberg. Later he worked for the chemical company Meister Lucius und Brüning . He supervised the production of Fuchsine and researched violet colorants...

 was a regular guest of his father; thus after finishing the gymnasium, Friedländer studied chemistry in Königsberg
University of Königsberg
The University of Königsberg was the university of Königsberg in East Prussia. It was founded in 1544 as second Protestant academy by Duke Albert of Prussia, and was commonly known as the Albertina....

 in the laboratories of Gräbe. Later he studied at the Strasbourg
University of Strasbourg
The University of Strasbourg in Strasbourg, Alsace, France, is the largest university in France, with about 43,000 students and over 4,000 researchers....

 and Munich where he assisted Adolf von Baeyer
Adolf von Baeyer
Johann Friedrich Wilhelm Adolf von Baeyer was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry. Born in Berlin, he initially studied mathematics and physics at Berlin University before moving to Heidelberg to study chemistry with Robert Bunsen...

. He received his PhD for the work with Baeyer and completed his habilitation in 1883. He left the well-equipped laboratories of Baeyer in Munich in 1884 to work in the small company K. Oehler in Offenbach. In 1888, he became professor at the University of Karlsruhe.
During a visit at his parents in Königsberg, he got engaged and married Martha Kobligk; they had three daughters. Although he liked staying in Germany, Friedländer accepted a position at the Technologische Gewerbemuseum in Vienna
Vienna
Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

 in 1895. During that time, he discovered the thioindigo
Thioindigo
Thioindigo is an organosulfur compound that is used for dying polyester fabrics. It is related to the more common dye indigo by replacement of two NH groups with sulfur atoms....

. His research on the color variations in substituted indigoes yielded numerous patents and was applied in industrial production. Friedländer isolated and analyzed the natural dye
Natural dye
Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources – roots, berries, bark, leaves, and wood — and other organic sources such as fungi and lichens....

stuff of Tyrian purple
Tyrian purple
Tyrian purple , also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye, which is extracted from sea snails, and which was possibly first produced by the ancient Phoenicians...

. He was able to obtain 12,000 Murex brandaris from biologists working at the Mediterranean sea. In a complicated process, he isolated 1.4 g of pure Tyrian purple. Contrary to his expectations, the compound did not contain sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, but was a bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

 substituted indigo
Indigo
Indigo is a color named after the purple dye derived from the plant Indigofera tinctoria and related species. The color is placed on the electromagnetic spectrum between about 420 and 450 nm in wavelength, placing it between blue and violet...

, which had been already synthesized back in 1903. Friedlander was awarded the Lieben Prize
Lieben Prize
The Ignaz Lieben Prize is an annual Austrian award for young scientists working in the fields of molecular biology, chemistry, or physics.The Ignaz Lieben Prize has been called the Austrian Nobel Prize. It is similar in intent but somewhat older than the Nobel Prize. The Austrian merchant Ignaz L...

 for this discovery.

In 1911, Friedländer abandoned his position in Vienna and joined the University of Darmstadt. The University was not far from the dye factories Chemische Fabrik Kalle, Höchst
Höchst (Frankfurt am Main)
Höchst is a district of Frankfurt am Main, Germany. It is part of the Ortsbezirk West, and is subdivided into 4 Stadtbezirke.Höchst am Main became part of Frankfurt am Main in 1928 together with its boroughs Sindlingen, Unterliederbach and Zeilsheim. It is situated 10 km west of downtown...

 and Cassella that helped Friedländer in his research on dyes. In 1911, he was awarded the Adolf-von-Baeyer-Prize.

During World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, Friedländer worked at the Kaiser Wilhelm Institute for Physical Chemistry and Elektrochemistry together with Fritz Haber
Fritz Haber
Fritz Haber was a German chemist, who received the Nobel Prize in Chemistry in 1918 for his development for synthesizing ammonia, important for fertilizers and explosives. Haber, along with Max Born, proposed the Born–Haber cycle as a method for evaluating the lattice energy of an ionic solid...

. The poor living standards after the war affected his health, and after a trip in the summer of 1923 from Darmstadt to Biebrich
Biebrich
Biebrich is the name of two places in Germany.*Biebrich, a borough of Wiesbaden, Hesse, until 1926 an independent town*Biebrich, Rhineland Palatinate, a small municipality in the Rhein-Lahn district, near Katzenelnbogen...

, Friedländer had to stay in a hospital. His health problems gradually deteriorated and on September 4, 1923, he died in Darmstadt.

The chemical reaction of 2-aminobenzaldehydes with ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s to form quinoline
Quinoline
Quinoline is a heterocyclic aromatic organic compound. It has the formula C9H7N and is a colourless hygroscopic liquid with a strong odour. Aged samples, if exposed to light, become yellow and later brown...

  derivatives, which Friedländer discovered in 1882, is today known as the Friedländer synthesis
Friedländer synthesis
The Friedländer synthesis is the chemical reaction of 2-aminobenzaldehydes with ketones to form quinoline derivatives. It is named after German chemist Paul Friedländer ....

.
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