Process for preparing nitrile compounds from ethylenically unsaturated compounds
The present invention concerns a process for hydrocyanating ethylenically unsaturated organic compounds to compounds containing at least one nitrile function. It relates more particularly to the hydrocyanation of diolefins such as butadiene or of substituted olefins such as alkenenitriles, for instance pentenenitriles. According to the process of the invention the reaction is implemented in the presence of a metal complex catalyst comprising a transition metal such as nickel and an organic ligand.
1. A process for hydrocyanating an ethylenically unsaturated aliphatic nitrile, or a linear pentenenitrile, by reacting it in a liquid medium with hydrogen cyanide in the presence of a catalyst corresponding to the general formula (II):
M[L f ] t (II)
wherein:
M is Ni,
L f represents an organic ligand of formula (I) and
t represents a number between 1 and 4 (inclusive) wherein the organic ligand corresponds to the general formula I below:
in which:
T and T 1 , represent a phosphorus atom,
R 1 , R 2 , R 3 and R 4 represent a substituted or unsubstituted phenyl group, having one or more rings, which are in fused form or not, optionally having one or more heteroatoms,
U 1 , U 2 , U 3 and U 4 represent an oxygen atom,
R 5 and R 6 , represent a substituted or unsubstituted phenyl group,
n is equal to 0, and
L 1 represents SO 2 .
2. The process according to claim 1 , wherein the organic ligand of formula I is selected from the group consisting of:
3. The process according to claim 1 , wherein the reaction is carried out in a single-phase medium.
4. The process according to claim 1 , wherein the liquid medium further comprises a solvent for the catalyst which is miscible with a phase comprising the compound to be hydrocyanated at the hydrocyanation temperature.
5. The process according to claim 1 , wherein the transition metal compounds are nickel compounds in which nickel is in oxidation state zero, nickel carboxylates, carbonate, bicarbonate, borate, bromide, chloride, citrate, thiocyanate, cyanide, formate, hydroxide, hydrophosphite, phosphite, phosphate and derivatives, iodide, nitrate, sulphate, sulphite, arylsulphonates or alkylsulphonates.
6. The process according to claim 1 , wherein the transition metal is used in a amount of between 10 −4 and 1 mol of transition metal per mole of hydrocarbon compound and wherein the organic ligand of formula (I) is used in a number of moles of from 0.5 to 50 relative to 1 mol of transition metal.
7. The process according to claim 1 , wherein the hydrocyanation reaction is carried out at a temperature from 10° C. to 200° C.
8. The process according to claim 1 for hydrocyanating ethylenically unsaturated nitrile compounds to dinitriles, being operated in the presence of a catalyst system comprising at least one transition metal compound, at least one organic compound of formula (I) and a cocatalyst composed of at least one Lewis acid.
9. The process according to claim 8 , wherein the ethylenically unsaturated nitrile compounds are pent-3-enenitrile, pent-4-enenitrile or mixtures thereof.
10. The process according to claim 9 , wherein the linear pentenenitriles contain amounts of other compounds selected from the group consisting of 2-methylbut-3-enenitrile, 2-methylbut-2-enenitrile, pent-2-enenitrile, valeronitrile, adiponitrile, 2-methylglutaronitrile, 2-ethylsuccinonitrile and butadiene.
11. The process according to claim 8 , wherein the Lewis acid is selected from salts selected from the group of halides, sulphates, sulphonates, haloalkylsulphonates, perhaloalkylsulphonates, haloalkylacetates, perhaloalkylacetates, carboxylates and phosphates.
12. The process according to claim 8 , wherein the Lewis acid is zinc chloride, zinc bromide, zinc iodide, manganese chloride, manganese bromide, cadmium chloride, cadmium bromide, stannous chloride, stannous bromide, stannous sulphate, stannous tartrate, indium trifluoromethylsulphonate, indium trifluoroacetate, zinc trifluoroacetate, lanthanum chloride, cerium chloride, praseodymium chloride, neodymium chloride, samarium chloride, europium chloride, gadolinium chloride, terbium chloride, dysprosium chloride, hafnium chloride, erbium chloride, thallium chloride, ytterbium chloride, lutetium chloride, lanthanum bromide, cerium bromide, praseodymium bromide, neodymium bromide, samarium bromide, europium bromide, gadolinium bromide, terbium bromide, dysprosium bromide, hafnium bromide, erbium bromide, thallium bromide, ytterbium bromide, lutetium bromide, cobalt chloride, ferrous chloride, or yttrium chloride.
13. The process according to claim 8 , wherein the Lewis acid employed represents from 0.01 to 50 mol per mole of transition metal compound.
14. The process according to claim 8 , wherein 2-methylbut-3-enenitrile, present in the reaction mixture originating from butadiene hydrocyanation, is isomerized to pentenenitriles in the absence of hydrogen cyanide, in the presence of a catalyst comprising at least one organic ligand of general formula (I) and at least one transition metal compound.
15. The process according to claim 14 , wherein the 2-methylbut-3-enenitrile subjected to isomerization is employed alone or in a mixture with 2-methylbut-2-enenitrile, pent-4-enenitrile, pent-3 -enenitrile, pent-2-enenitrile, butadiene, adiponitrile, 2-methylglutaronitrile, 2-ethylsuccinonitrile or valeronitrile.
16. The process according to claim 14 , wherein the isomerization reaction is carried out at a temperature from 10° C. to 200° C.
17. The process according to claim 14 , wherein the isomerization of 2-methylbut-3-enenitrile to pentenenitriles is carried out in the presence of at least one transition metal compound, at least one organic phosphorous ligand of the formula (I) and a cocatalyst composed of at least one Lewis acid.