METHOD FOR THE SYNTHESIS OF HETEROCYCLIC HYDROGEN PHOSPHINE OXIDE
A method for the synthesis of a heterocyclic hydrogen phosphine oxide, having the general formula: wherein: R is a aliphatic or aromatic divalent group optionally including one or more heteroatoms and optionally having one or more substituents and X and Y are independently selected from —O—, —C(O)O— and —NR′— wherein R′ is a monovalent group optionally having one or more heteroatoms including the steps of: a) forming a reaction mixture by mixing a compound having the general formula HX—R—YH and tetraphosphorus hexaoxide; and b) recovering the resulting compound comprising the heterocyclic hydrogen phosphine oxide.
1 . A method for the synthesis of a heterocyclic hydrogen phosphine oxide, having the general formula:
wherein:
R is a aliphatic or aromatic divalent group optionally comprising one or more heteroatoms and optionally comprising one or more substituents and
X and Y are independently selected from —O—, —C(O)O— and —NR′—
wherein R′ is a monovalent group optionally comprising one or more heteroatoms comprising the steps of:
a) forming a reaction mixture by mixing a compound having the general formula HX—R—YH and tetraphosphorus hexaoxide; and
b) recovering the resulting compound comprising the heterocyclic hydrogen phosphine oxide.
2 . The method according to claim 1 wherein the molar ratio of the compound with general formula HX—R—YH to tetraphosphorus hexaoxide is comprised between 5.0 and 2.0.
3 . The method according to claim 1 , wherein the compound with general formula HX—R—YH is characterized in that:
X and Y are independently selected from —O—, —C(O)O— and —NR′—, wherein R′ is an alkyl, alkenyl or alkynyl radical, having 1 to 10 carbon atoms, optionally comprising one or more heteroatoms selected from the group consisting of oxygen, nitrogen, sulphur and phosphorus, and optionally comprising one or more substituents selected from the group consisting of alkoxy, alkyl alkanoate, alkyl carboxylate, nitrile, carbamoyl, sulfanyl and halogen;
R is an alkylene, alkenylene or alkynylene radical having 2 to 20 carbon atoms and optionally comprising one or more heteroatoms selected from the group consisting of oxygen, nitrogen, phosphorus and sulfur and optionally comprising one or more substituents selected from the group consisting of aryl, alkaryl, alkenaryl, alkynaryl, alkoxy, alkyl alkanoate, alkyl carboxylate, nitrile, carbamoyl, sulfanyl and halogen or
R is an aryl or biaryl radical, optionally comprising one or more heteroatoms selected from the group consisting of oxygen, nitrogen, phosphorus and sulfur and optionally comprising one or more substituents R′; and
X and Y are separated by 10 or less carbon-carbon and/or carbon-heteroatom single and/or double and/or triple bonds; whereby for cyclic aliphatic or aromatic compounds the lowest number of bonds is meant.
4 . The method according to claim 1 wherein step a) comprises a solvent selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, acetonitrile, dichloromethane and mixtures thereof.
5 . The method according to claim 1 wherein step a) comprises a dehydrating agent selected from the group consisting of organic dehydrating agents preferably an acid anhydride selected from the group consisting of acetic anhydride, trifluoroacetic anhydride and mixtures thereof; an orthoester such as trimethyl orthoformate or a carbodiimide such as N,N′-dicyclohexylcarbodiimide.
6 . The method according to claim 1 wherein step a) comprises a dehydrating agent selected from the group consisting of inorganic dehydrating agents.
7 . The method according to claim 1 wherein the dehydrating agent does not react with the reactants and wherein said dehydrating agent is added from the beginning of the reaction.
8 . The method according to claim 1 wherein tetraphosphorus hexaoxide is added over a period of time comprised between 5 minutes and 2 hours to the compound with general formula HX—R—YH, comprising the solvent, standing at a temperature comprised between 10° C. and 80° C.
9 . The method according to claim 1 wherein step a), after the completion of the tetraphosphorus hexaoxide addition, is maintained at a temperature comprised between 10° C. and 80° C. for a period of time comprised between 10 minutes and 20 hours.
10 . The method according to claim 1 wherein the resulting compound comprising the heterocyclic hydrogen phosphine oxide is recovered in step b) through distilling off the solvent.
11 . The method according to claim 1 wherein the resulting compound comprising the heterocyclic hydrogen phosphine oxide is recovered in step b) through crystallization.
12 . The method according to claim 1 wherein the compound with general formula HX—R—YH is selected from the group consisting of ethylene glycol; 1,2-propanediol; 2,2-dimethyl-1,3-propanediol; 2-phenyl-1,2-propanediol; 3-allyloxy-1,2-propanediol; 3-chloro-1,2-propanediol; 1,3-butanediol; 2,3-butanediol; 2,3-dimethyl-2,3-butanediol; 1,1,2,2-tetraphenyl-1,2-ethanediol; triethylene glycol; 1,10-decanediol; 2,2′-biphenol, and 1,1′-bis-2-naphtol; 2-hydroxybenzoic acid; pinanediol and (S)-(−)-α,α-diphenyl-2-pyrrolidinemethanol.
13 . The method according to claim 1 wherein the weight ratio of solvent to the total amount of reactants in step a) is comprised between 0.5 and 5.
14 . The method according to claim 1 wherein the molar ratio of the compound with general formula HX—R—YH to tetraphosphorus hexaoxide is comprised between 4.5 and 2.5.
15 . The method according to claim 1 wherein the molar ratio of the compound with general formula HX—R—YH to tetraphosphorus hexaoxide is comprised between 4.0 and 3.0.
16 . The method according to claim 1 wherein step a) comprises a dehydrating agent selected from the group consisting of zeolite with a pore size of 4 Å.