Friedrich Karl Johannes Thiele developedpreparation glyoxal bis

Friedrich Karl Johannes Thiele – discoverer of condensation of ketones & aldehydes

Category : Personalities
Published by : Data Research Analyst, Worldofchemicals.com

Biography & contributions

Friedrich Karl Johannes Thiele was a German chemist born on May 13, 1865 – died on April 17, 1918. Thiele was well credited for developing many laboratory techniques related to isolation of organic compounds.

Thiele’s other important contributions include preparation of glyoxal bis (guanylhydrazone, proposed the idea of partial valence hypothesis, discovered condensation of ketones and aldehydes with cyclopentadiene as a route to fulvenes and also synthesized an iminodibenzyl nucleus. In 1917 Thiele described a device called Thiele tube for the accurate determination of melting points.

He also recognized that these deeply colored species were related to but isomeric with benzene derivatives.

Ketones


Ketones are the class of organic compounds characterized by the presence of a carbonyl group in which the carbon atom is covalently bonded to an oxygen atom. Ketone compounds have important physiological properties. They are found in several sugars and in compounds for medicinal use, including natural and synthetic steroid hormones.

Ketones structure is described as trigonal planar around the ketonic carbon, with C-C-O and C-C-C bond angles of approximately 120°. Ketones differ from aldehydes in that the carbonyl group (CO) is bonded to two carbons within a carbon skeleton. Ketones are hydrogen-bond acceptors. Ketones are not usually hydrogen-bond donors and cannot hydrogen-bond to them. Ketones are highly reactive, although less so than aldehydes, to which they are closely related.

Much of their chemical activity results from the nature of the carbonyl group. Ketones readily undergo a wide variety of chemical reactions. Ketones give positive results in Brady's test, the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with Tollens' reagent or with Fehling's solution.

Ketones are produced on massive scales in industry as solvents, polymer precursors, and pharmaceuticals. These are produced when the body burns fat for energy or fuel. Ketones also produced when you lose weight or if there is not enough insulin to help your body use sugar for energy. They are most widely used as solvents, especially in industries manufacturing explosives, lacquers, paints, and textiles. Ketones are also used in tanning, as preservatives, and in hydraulic fluids

Aldehydes


Aldehyde can be defined as any of a class of organic compounds, in which a carbon atom shares a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom or group of atoms. The double bond between carbon and oxygen is characteristic of all aldehydes and is known as the carbonyl group. Many aldehydes have pleasant odours, and in principle, they are derived from alcohols by dehydrogenation. Pure acetone is a colourless, somewhat aromatic, flammable, mobile liquid that boils at 56.2 °C (133 °F). Aldehydes are also useful as solvents and perfume ingredients and as intermediates in the production of dyes and pharmaceuticals. Certain aldehydes are involved in physiological processes.

Image Reference

[1] © From, http://www.visualphotos.com/image/1x6037907/silver_mirror_test_for_aldehydes

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