- METHOD OF THE SYNTHESIS OF DIALKYL HALOALKYLPHOSPHONATES AND DIALKYL HALOALKYLOXYALKYLPHOSPHONATES
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The invention deals with the method of the synthesis of dialkyl haloalkylphosphonates and dialkyl haloalkyloxyalkylphosphonates via a microwave-heated Michaelis-Arbuzov reaction of trialkylphosphites with dihaloalkanes or bis(haloalkyl)ethers in a closed vessel, during which the reaction mixture, containing a dihaloalkane or bis(haloalkyl)ether and a trialkylphosphite, is heated with microwave radiation with the standard frequency (2.45 GHz) to reach a reaction temperature which is specific for each individual halogen. In the subsequent reaction of the first dihaloalkane or bis(haloalkyl)ether halogen atom with trialkyl phosphite, the desired dialkyl haloalkylphosphonate or dialkyl haloalkyloxyalkylphosphonate is formed, but the reaction of its halogen atom with the so-far present trialkylphosphite, leading to the creation of the relevant bisphosphonate, no longer takes place. In the case of an inhomogeneous reaction mixture, also the desired product in the amount of 0.1-5 molar % is added to the reaction mixture for its homogenization, which homogenizes it and thus precludes its uncontrollable overheating. The entire process of synthesis is more effective, faster, less expensive and more environmentally friendly than the methods described so far in the literature. The possibility of performing the described procedure also in a continuous-flow microwave reactor allows industrial production with minimal demands on an optimization of the reaction conditions for larger quantities, eliminates some security risks, dramatically reduces the spatial demands in production and reduces the need for the usage of large-tonnage industrial reactors.
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Page/Page column 11-13
(2012/02/13)
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- Efficient and 'green' microwave-assisted synthesis of haloalkylphosphonates via the Michaelis-Arbuzov reaction
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This paper deals with a novel, efficient and environmentally friendly synthesis of dialkyl haloalkylphosphonates via a microwave-assisted Michaelis-Arbuzov reaction. The approach is solventless, requires only one equivalent of each of the starting compounds, and provides high yields of pure products from which the impurities are easy to remove. The process has been optimised for batch and flow reactors and is especially profitable for the production of key intermediates in synthesis of Ethephon or acyclic nucleoside phosphonates such as adefovir, tenofovir, and cidofovir. The Royal Society of Chemistry.
- Jansa, Petr,Holy, Antonin,Dracinsky, Martin,Baszczynski, Ondrej,Cesnek, Michal,Janeba, Zlatko
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supporting information; experimental part
p. 882 - 888
(2011/06/20)
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- Optimization of 2-chloroethylphosphonic acid synthesis by acid hydrolysis of dialkyl-2-chloroethylphosphonate compounds. Influence of the nature of alkyl phosphonate functions
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2-Chloroethylphosphonic acid (ethephon) 1 is very much used in agriculture as a plant regulator.It is an especially good stimulant used to increase the latex production of Hevea brasiliensis.Ethephon is generally obtained by HCl hydrolysis of bis(2-chloroethyl)-2-chloroethylphosphonate, previously prepared by Arbuzov rearrangement of tri(2-chloroethyl)phosphite.However, because of the low reactivity of 2-chloroethylphosphonate functions towards acid hydrolysis, this synthetic way is not convenient to prepare pure 2-chloroethylphosphonic acid with high yields.The present purpose was to study the hydrolysis of various dialkyl-2-chloroethylphosphonates in view to define an efficient synthetic protocol, leading to very pure crystallized ethephon with high yields. - Keywords: 2-chloroethylphosphonic acid; ethephon; dialkyl-2-chloroethylphosphonate; Arbuzov reaction; trialkyl phosphite; acid hydrolysis
- Cauret, Laurent,Brosse, Jean-Claude,Derouet, Daniel,Livonniere, Hugues De
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p. 463 - 470
(2007/10/03)
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