Gustavson reaction
Gustavson reaction or Freund-Gustavson reaction is a reaction of organic chemistry and was named after the Russian chemist Gawriil Gawriilowitsch Gustawson (1843-1908). It is based on the Freund reaction discovered in 1881 , which Gustavson improved in 1887 and thus facilitated the synthesis of cyclopropane .
Overview reaction
The Gustavson reaction is a reaction of 1,3-dihalopropane with zinc , which replaces the sodium in the Freund reaction. Here you get a cyclopropane:
Gustavson has found that without the addition of water or alcohol, 1,3-dibromopropane does not react with the zinc below 100 ° C.
mechanism
The mechanism has not yet been fully clarified and is similar to the mechanism of the Freund reaction or the Wurtz synthesis . This will be shown using the example of 1,3-dibromopropane and zinc. In the first step, 1,3-dibromopropane ( 1 ) reacts with zinc to form a carbanionic organometallic compound 2 . The zinc in 2 has a positive partial charge and in the next step is nucleophilically attacked by the bromine at the C 1 atom, the bromine taking the electron pair bond to the carbon atom with it. At the same time, the partially negatively charged carbon atom attacks the carbon atom of the C-Br bond. As a result, zinc dibromide is split off and cyclopropane 3 is formed through ring closure .
Individual evidence
- ^ David E. Lewis, Early Russian Organic Chemists and Their Legacy . Springer, 2012, ISBN 978-3-642-28218-8 , pp. 104 , doi : 10.1007 / 978.3.642.28219.5 .
- ^ Zerong Wang: Comprehensive Organic Name Reactions and Reagents . John Wiley & Sons, 2009, ISBN 978-0-471-70450-8 , pp. 1123-1125 .
- ↑ G. Gustavson: About a new method of representation of trimethylene . In: Journal for Practical Chemistry . tape 36 , no. 1 , 1887, p. 300-303 , doi : 10.1002 / prac.18870360127 .
- ^ Zerong Wang: Comprehensive Organic Name Reactions and Reagents . John Wiley & Sons, 2009, ISBN 978-0-471-70450-8 , pp. 1124 .