Method for producing nitriles by elimination of water from aldehyde oximes with alkylphosphonic anhydrides
View Patent ↗The invention relates to a method for producing the nitrites of formula: R 1 —CN by reacting aldehyde oximes (R 1 CN═N—OH) with cyclic alkylphosphonic anhydrides at a temperature ranging from −100 to +120° C., wherein R 1 represents H, a linear or branched C 1 -C 12 alkyl group, a C 3 -C 10 cycloalkyl, alkenyl or an aryl or heteroaryl group. The cyclic phosphonic anhydride preferably used is a 2,4,6-substituted 1,3,5,2,4,6-trioxatriphosphinane-2,4,6-trioxide of formula (I), wherein R′ independently represents allyl, aryl or open-chain or branched C 1 to C 12 alkyl groups. Optionally, the reaction can be carried out in the presence of a tertiary amine base NR 2 3
1. Process for preparing nitriles of the formula (II)
R 1 —CN (II)
said process comprising reacting
aldehyde oximes (R1CH=N—OH)
with cyclic alkylphosphonic anhydrides at a reaction temperature in the range from −100 to +120° C.,
where R 1 is H, a linear or branched C 1 -C 12 -alkyl radical, a C 3 -C 10 -cycloalkyl radical, alkenyl radical or an aryl or heteroaryl radical.
2. The process as claimed in claim 1 , wherein the cyclic alkylphosphonic anhydride is a 2,4,6-substituted 1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide of the formula (I)
where R′ is independently allyl, aryl or open-chain or branched C 1 to C 12 -alkyl radicals.
3. The process as claimed in claim 2 , wherein R′ is selected from one or more of a methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, pentyl, or hexyl, radical.
4. The process as claimed in claim 1 , wherein the reaction is performed in the presence of an amine base of the formula (III)
NR 2 3 (III)
where R 2 is H, allyl, or open-chain, cyclic or branched C 1 to C 12 -alkyl radicals, aryloxy, allyloxy or alkoxy having open-chain cyclic or branched C 1 to C 12 -alkyl radicals, or a combination thereof.
5. The process as claimed in claim 1 , wherein the cyclic alkylphosphonic anhydride is added to the reaction solution either as a melt or dissolved in a solvent.
6. The process as claimed in claim 5 , wherein the cyclic alkylphosphonic anhydride is added in a solvent and the solvent is aprotic.
7. The process as claimed in claim 1 , wherein the aldehyde oxime is heated to the reaction temperature before the cyclic alkylphosphonic anhydride is added.
8. The process as claimed in claim 1 , wherein the cyclic alkylphosphonic anhydride is used in one third of the stoichiometric amount up to a superstoichiometric amount in relation to the aldehyde oxime.
9. The process as claimed in claim 2 , wherein R 1 is selected from one or more of an ethyl propyl, or butyl radical.