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Beckmann, Ernst Otto

reaction molecular method rise

(1853–1923) German chemist: discovered a rearrangement reaction and a method for determining relative molecular mass in solution.

Beginning as an apprentice pharmacist, Beckmann turned to chemistry with success, being professor at three universities before being appointed first director of the Kaiser Wilhelm Institute for Chemistry at Berlin-Dahlem in 1912. His distinction began in 1886, when he discovered the Beckmann rearrangement–the reaction of ketoximes with acid reagents to give a substituted amide, often in high yield:

The reaction has been used to prepare some amides, and also in studies on stereochemistry and on reaction mechanism. Beckmann’s work led him to seek a general method for finding the relative molecular mass of a reaction product; he devised a method, using Law, by measuring the rise in boiling point of a solvent caused by dissolving in it a known amount of the substance whose molecular mass is required. To measure this small temperature rise he devised the Beckmann thermometer, which has a reservoir for adjusting its range and will measure accurately a small rise in temperature.

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