Ružička ring synthesis

The Ružička ring synthesis (also called Ružička cyclization or Ružička reaction ) is a name reaction in organic chemistry that was first described in 1926 by Lavoslav Ružička . With the help of this synthesis cyclic ketones can be produced.

Overview reaction

A long-chain α, ω- dicarboxylic acid 1 is converted into a cyclic ketone 2 by heating at 350-400 ° C. and with the aid of a suitable catalyst (here thorium dioxide ) .

General

Ružička salt distillation is a practically obsolete process. However, it is suitable for the production of cycloheptanone . This process gives a good yield, especially in the synthesis of cyclopentanones and cyclohexanones . Ružička self-synthesized macrocyclic ketones using this method. Experiments were carried out with the series of polymethylene dicarboxylic acids. It was found that the effectiveness of this synthesis is strongly dependent on which metal a salt is used from. The salts of thorium and cerium were particularly suitable as catalysts for the Ružička ring synthesis.

Examples

The method was transferred by Ružička to the series of polymethylene dicarboxylic acids. The series begins with nonane-1,9-dicarboxylic acid 1 from which cyclodecanone 2 can be synthesized.

The last member of this series is the heptadecane-1,17-dicarboxylic acid 3 from which an 18-membered ring was produced for the first time; cyclooctadecanone 4 is formed .

application

The low yield in the production of macrocyclic ketones is the reason that the process is not suitable for industrial use. For the synthesis of cyclopentanones and cyclohexanones there are also more economical processes with better yields for industry.

Individual evidence

1. ↑ L. Ruzicka; M. Stoll; H. Schinz: On the knowledge of the carbon ring II. Synthesis of the carbocyclic ketones from the ten to the eighteenth ring . In: Helvetica Chimica Acta . tape 9 , no. 1 . Verlag GmbH & Co. KGaA, Weinheim 1926, p. 249–264 , doi : 10.1002 / hlca.19260090130 .
2. ↑ H. Krauch, H. Kunz: reactions of organic chemistry . In: Metallocenes . 6th edition. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1997, ISBN 978-3-527-29713-9 , p. 468-469 , doi : 10.1002 / 9783527625116 .
3. ↑ Houben-Weyl, K. Ziegler: General chemical methods . In: Eugen Müller (ed.): Methods of organic chemistry . 4th edition. tape 4 , no. 2 . Georg Thieme Verlag, Stuttgart 1955, ISBN 978-3-13-196264-5 , p. 754-755 , doi : 10.1055 / b-003-117810 .
4. ↑ Entry on Ružička cyclization. In: Römpp Online . Georg Thieme Verlag, accessed on December 10, 2018.