Methods for producing alkenes

Abstract

To produce a hydrogenated alkene by way of hydrogen substitution.SOLUTION: An alkene production method includes a step in which a hydrogenation reaction is performed in the presence of an activated carbon catalyst supporting a precious metal or a noble metal.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a process for producing alkenes. [Background technology]

[0002] Patent Document 1 discloses that in the presence of a catalyst made of palladium or platinum supported on activated carbon, A process for preparing trifluoroethylene is disclosed which comprises contacting chlorotrifluoroethylene with hydrogen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special publication 2013-534529 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to produce hydrogenated alkenes by hydrogen substitution. [Means for solving the problem]

[0005] The present disclosure encompasses the following configurations.

[0006] Section 1. General formula (1):

[0007] [ka]

[0008] (In the formula, R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group. A method for producing an alkene represented by the formula: General formula (2):

[0009] [ka]

[0010] (wherein X is a halogen atom, and R 1 , R 2 , and R 3 are the same or different and are fluorine or represents a perfluoroalkyl group. In the formula, when X is a chlorine atom, R 1 , R 2 , and R 3 What At least one of them represents a perfluoroalkyl group. The alkene represented by the formula (I) is subjected to a hydrogenation reaction in the presence of an activated carbon catalyst carrying a noble metal or a rare metal. A manufacturing method comprising the step of reacting

[0011] Section 2. Item 2. The production method according to Item 1, wherein the hydrogenation reaction is carried out in a gas phase.

[0012] Section 3. The noble metal or rare metal is at least one noble metal selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and manganese (Mn). 3. The method according to claim 1 or 2, wherein the metal is a rare metal.

[0013] Section 4. CF3-CF=CH-CF3; CF3-CFH-CFH-CF3; and CF3-CFH-CFH-CF2H;

[0014] Section 5. Item 5. The composition according to item 4, which is used as an etching gas, a refrigerant, a heat transfer medium, a deposit gas, a building block for organic synthesis, or a cleaning gas. [Effects of the Invention]

[0015] According to the present disclosure, hydrogenated alkenes can be produced efficiently by hydrogen substitution. DETAILED DESCRIPTION OF THE INVENTION

[0016] In this specification, the term "containing" is a concept that encompasses all of "comprise," "consist essentially of," and "consist only of." Furthermore, in this specification, when a numerical range is expressed as "A to B," it means A or more and B or less.

[0017] As a result of intensive research, the present inventors have found that by carrying out the step of hydrogenating an alkene, which is a raw material compound, in the presence of a palladium-supported activated carbon catalyst, the hydrogenation reaction can be carried out efficiently and hydrogenated alkenes can be produced with a high conversion rate (yield) and high selectivity.

[0018] The present disclosure was completed as a result of further research based on this finding.

[0019] The present disclosure includes the following embodiments.

[0020] The general formula (1) of the present disclosure:

[0021] [ka]

[0022] (In the formula, R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group. The method for producing an alkene represented by the formula: General formula (2):

[0023] [ka]

[0024] (wherein X is a halogen atom, and R 1 , R 2 , and R 3 are the same or different and are fluorine or represents a perfluoroalkyl group. In the formula, when X is a chlorine atom, R 1 , R 2 , and R 3 What At least one of them represents a perfluoroalkyl group. in the presence of an activated carbon catalyst supporting a noble metal or a rare metal.

[0025] In the production method of the present disclosure, the hydrogenation reaction step is preferably carried out in a gas phase.

[0026] In the manufacturing method of the present disclosure, preferably, the noble metal or rare metal is at least one noble metal or rare metal selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and manganese (Mn).

[0027] The composition of the present disclosure comprises: CF3-CF=CH-CF3; CF3-CFH-CFH-CF3; and Contains CF3-CFH-CFH-CF2H;

[0028] The compositions of the present disclosure are preferably used as etching gases, refrigerants, heat transfer media, deposition gases, building blocks for organic synthesis, or cleaning gases.

[0029] By satisfying the above requirements, the present disclosure enables the hydrogenation reaction to proceed efficiently, and hydrogenated alkenes to be produced with high conversion (yield) and high selectivity.

[0030] In the present disclosure, the term "conversion rate" means the ratio (mol %) of the total molar amount of compounds other than the raw material compound (such as hydrogenated alkenes) contained in the gas effluent from the reactor outlet to the molar amount of the raw material compound (alkene containing a halogen atom) supplied to the reactor.

[0031] In the present disclosure, the term "selectivity" means the ratio (mol%) of the total molar amount of the target compound (hydrogenated alkene) contained in the effluent gas from the reactor outlet to the total molar amount of compounds other than the raw material compound (hydrogenated alkene, etc.) in the effluent gas.

[0032] The method for producing an alkene according to the present disclosure can efficiently hydrogenate an alkene containing a halogen atom, which is a raw material compound, and can produce a hydrogenated alkene with a high conversion rate (yield) and high selectivity.

[0033] (1) Raw material compound The raw material compound of the present disclosure is represented by the general formula (2):

[0034] [ka]

[0035] (wherein X is a halogen atom, and R 1 , R 2 , and R 3 are the same or different and are fluorine or represents a perfluoroalkyl group. In the formula, when X is a chlorine atom, R 1 , R 2 , and R 3 What At least one of them represents a perfluoroalkyl group. It is an alkene represented by the formula:

[0036] In the alkene formula (2), X is a halogen atom, and R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group.

[0037] In the alkene formula (2), when X is a chlorine atom, R 1 , R 2 , and R 3 Any one or more of the groups represents a perfluoroalkyl group.

[0038] The halogen atom is preferably a fluorine atom, a bromine atom, an iodine atom, or a chlorine atom.

[0039] The perfluoroalkyl group is an alkyl group in which all hydrogen atoms are substituted with fluorine atoms. The perfluoroalkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

[0040] The perfluoroalkyl group is preferably a linear or branched perfluoroalkyl group. The perfluoroalkyl group is preferably a trifluoromethyl group (CF3-) or a pentafluoroethyl group (C2F5-).

[0041] The raw material compound, an alkene represented by general formula (2), is reacted with an active catalyst supported on a noble or rare metal. The carbon number is preferably 2 to 8, more preferably 2 to 4, and even more preferably 4, in that the hydrogenation reaction proceeds efficiently in the presence of a carbon catalyst and a hydrogenated alkene can be produced with a high conversion, yield, and / or high selectivity.

[0042] The starting compound, an alkene represented by general formula (2), is R 1 , R 2 , and R 3 are the same or different represents a fluorine or perfluoroalkyl group.

[0043] The alkene represented by the general formula (2) of the raw material compound is preferably perfluoro-2-butene (F3C-CF=CF-CF3), perfluoro-1-butene (CF3-CF2-CF=CF2), or the like.

[0044] The starting compound, an alkene represented by general formula (2), can be used alone or in combination of two or more kinds. Commercially available alkenes can also be used.

[0045] (2) Hydrogenation reaction In the hydrogenation reaction step of the present disclosure, the alkene represented by general formula (2) is hydrogenated using palladium-supported activated carbon as a catalyst.

[0046] In the hydrogenation reaction step, the raw material compound, alkene represented by general formula (2), is hydrogenated. The carbon number is preferably 2 to 8, more preferably 2 to 4, and even more preferably 4, in that the modified alkene can be produced with a high conversion rate, yield, and / or high selectivity.

[0047] In the hydrogenation reaction step, the alkene represented by the general formula (2) as the raw material compound is converted into an alkene is preferably R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group.

[0048] The alkene represented by general formula (2), which is the raw material compound, is preferably perfluoro-2-butene (CF3-CF=CF-CF3), and the alkene represented by general formula (1), which is the target compound to be hydrogenated, is preferably 1,1,1,2,4,4,4-heptafluoro-2-butene (CF3-CF=CH-CF3)((Z / E)-1327myz)).

[0049] Activated carbon catalyst supporting precious or rare metals (Precious or rare metal catalyst supported on activated carbon) The hydrogenation reaction step of the present disclosure includes hydrogenating an alkene represented by general formula (2), which is a raw material compound, using an activated carbon catalyst supporting a noble metal or a rare metal as a catalyst; The target compound, an alkene represented by general formula (1), preferably 1,1,1,2,4,4,4-heptafluoro-2-butene, is produced by hydrogenation.

[0050] The hydrogenation reaction step is preferably carried out in a gas phase.

[0051] As the hydrogenation catalyst, the noble or rare metal is preferably at least one noble or rare metal selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and manganese (Mn).

[0052] As the hydrogenation catalyst, it is more preferable to use a palladium-supported activated carbon catalyst in which the noble or rare metal is palladium (Pd) and the carrier is activated carbon, which makes it possible to obtain a large metal surface area and achieve a fast hydrogenation reaction rate.

[0053] The particle size of the activated carbon carrier is preferably about 0.1 mm to 100 mm.

[0054] The amount of palladium supported relative to the total mass of the catalyst used in the hydrogenation reaction step is preferably about 0.01% by mass to 20% by mass, and more preferably about 0.1% by mass to 10% by mass.

[0055] The catalyst can be prepared by a wide variety of known methods. For example, a catalyst in which palladium metal is supported on an activated carbon carrier can be obtained by immersing the activated carbon carrier in a solution containing palladium metal to impregnate the carrier with the solution, followed by neutralization and calcination, if necessary. In this case, the amount of noble metal or rare metal supported on the carrier can be adjusted by adjusting the concentration of the solution, the impregnation time, etc.

[0056] Amount of hydrogen used (H 2 / alkene molar ratio) In the hydrogenation reaction step of the present disclosure, the alkene to be hydrogenated can be produced with a high conversion, yield, and / or high selectivity, and therefore the amount of hydrogen used is preferably 1 mole of alkene. Preferably, the amount is 0.1 to 10 moles (H2 / alkene molar ratio: 0.1 to 10), more preferably 1 to 5 moles (H2 / alkene molar ratio: 1 to 5), even more preferably 1 to 3 moles (H2 / alkene molar ratio: 1 to 3), and particularly preferably 1.1 moles (H2 / alkene molar ratio :1.1).

[0057] Reaction temperature of hydrogenation reaction The hydrogenation reaction step of the present disclosure uses a palladium-supported activated carbon catalyst, and the lower limit of the reaction temperature is preferably 100°C or higher, from the viewpoint of more efficiently proceeding the hydrogenation reaction from the raw material compound, further improving the conversion rate, and obtaining the target compound with a higher selectivity. The temperature is preferably 150°C or higher, and more preferably 200°C or higher.

[0058] In the hydrogenation reaction step, the upper limit of the hydrogenation reaction temperature is preferably 800°C or lower, more preferably 600°C or lower, and even more preferably 500°C or higher, from the viewpoint of more efficiently progressing the hydrogenation reaction, further improving the conversion rate, and enabling the target compound to be obtained with a higher selectivity, and from the viewpoint of further suppressing a decrease in selectivity due to decomposition or polymerization of the reaction product. The temperature is preferably 400°C or lower, and particularly preferably 400°C or lower.

[0059] Reaction time of hydrogenation reaction In the hydrogenation reaction step of the present disclosure, the reaction time for the hydrogenation reaction, for example, when a gas-phase flow reaction is employed, is the contact time of the raw material compound with the catalyst (W / F) [W: weight of metal catalyst (g), F: flow rate of raw material compound (cc / sec)], from the viewpoint of achieving a particularly high conversion rate by the hydrogenation reaction and obtaining the target compound in a higher yield and with a higher selectivity, preferably 1 g sec / cc to 120 g sec / cc, more preferably 3 g sec / cc to 100 g sec / cc, and even more preferably 5 g sec / cc to 80 g sec / cc. The above W / F specifies the reaction time, particularly when a gas-phase flow reaction is employed.

[0060] When a batch reaction is employed, the contact time can be appropriately set.

[0061] The contact time means the time during which the raw material compound (substrate) and the catalyst are in contact with each other.

[0062] Reaction pressure of hydrogenation reaction In the hydrogenation reaction step of the present disclosure, the reaction pressure for the hydrogenation reaction is preferably −0.05 MPa to 2 MPa, more preferably −0.01 MPa to 1 MPa, and even more preferably atmospheric pressure to 0.5 MPa, in order to allow the hydrogenation reaction to proceed more efficiently.

[0063] In this disclosure, unless otherwise specified, pressure is gauge pressure.

[0064] Hydrogenation reaction vessel In the hydrogenation reaction step of the present disclosure, the reactor into which the raw material compound and the catalyst are introduced and into which the hydrogenation reaction is carried out is not particularly limited in shape or structure as long as it can withstand the above-mentioned temperature and pressure. The reactor for the hydrogenation reaction is preferably a vertical reactor, a horizontal reactor, a multi-tubular reactor, or the like. The material of the reactor for the hydrogenation reaction is preferably glass, stainless steel, iron, nickel, an iron-nickel alloy, or the like.

[0065] Gas-phase reactions The hydrogenation reaction step of the present disclosure is preferably a gas-phase reaction, and can be carried out by either a flow system or a batch system in which a raw material compound (substrate) is continuously charged into a reactor and a target compound is continuously withdrawn from the reactor.

[0066] The reaction is preferably carried out in a flow system in order to prevent the target compound from remaining in the reactor and causing the reaction to proceed excessively.

[0067] Continuous gas flow type The hydrogenation reaction step of the present disclosure is preferably carried out in a gas phase, more preferably in a gas phase continuous flow system using a fixed bed reactor. When carried out in a gas phase continuous flow system, the equipment, operation, etc. can be simplified and it is economically advantageous.

[0068] In the hydrogenation reaction step, the atmosphere in which the hydrogenation reaction is carried out is preferably an inert gas atmosphere, a hydrogen fluoride gas atmosphere, or the like, from the viewpoint of suppressing catalyst deterioration. The inert gas is preferably nitrogen, helium, argon, or the like. Among the inert gases, nitrogen is preferably used from the viewpoint of reducing costs. The concentration of the inert gas is preferably 0 mol % to 50 mol % of the gas components introduced into the reactor.

[0069] When the hydrogenation reaction step is carried out in the gas phase in the presence of a catalyst, the target compound can be obtained with a higher selectivity by appropriately adjusting the reaction temperature and reaction time (contact time) particularly in accordance with the catalyst.

[0070] (3) Target compound The target compound of the present disclosure has the general formula (1):

[0071] [ka]

[0072] (In the formula, R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group. It is an alkene (hydrogenated alkene) represented by the formula:

[0073] Depending on the hydrogenation reaction step, the raw material compound is represented by the general formula (2): In the formula, the X (halogen atom) is replaced with a hydrogen atom to produce a hydrogen-substituted alkene.

[0074] In the formula (1) of the alkene, R 1 , R 2 , and R 3 are the same or different and are fluorine or perfluor represents an orthoalkyl group.

[0075] The perfluoroalkyl group is an alkyl group in which all hydrogen atoms are substituted with fluorine atoms. The perfluoroalkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

[0076] The perfluoroalkyl group is preferably a linear or branched perfluoroalkyl group. The perfluoroalkyl group is preferably a trifluoromethyl group (CF3-) or a pentafluoroethyl group (C2F5-).

[0077] The target alkene represented by general formula (1) is preferably a compound having 2 carbon atoms (C2 compound) to 8 carbon atoms (C8 compound), more preferably a C2 compound to a C4 compound, and even more preferably a C4 compound, in that the target alkene (halogen atom) represented by general formula (2), which is a raw material compound, can be efficiently hydrogenated in the presence of a palladium-supported activated carbon catalyst, and the hydrogenated alkene can be produced with a high conversion, yield, and / or high selectivity.

[0078] The alkene represented by the general formula (1) of the target compound is obtained by efficiently hydrogenating the alkene (halogen atom) represented by the general formula (2) of the raw material compound in the presence of a palladium-supported activated carbon catalyst, and the hydrogenated alkene is obtained with a high conversion rate, yield, and / or high selectivity. Preferably, R 1 , R 2 , and R 3 are the same or different and represent fluorine or a perfluoroalkyl group.

[0079] The alkene represented by the general formula (1) of the target compound is preferably 1,1,1,2,4,4,4-hepta. It is fluoro-2-butene.

[0080] The starting compound, an alkene represented by general formula (1), can be used alone or in combination of two or more kinds. Commercially available alkenes can also be used.

[0081] Preferred hydrogenation reaction The hydrogenation reaction step of the present disclosure preferably uses a palladium-supported activated carbon catalyst to hydrogenate perfluoro-2-butene as an alkene raw material compound, to produce an alkene as a target compound. The product produced is 1,1,1,2,4,4,4-heptafluoro-2-butene.

[0082] After the hydrogenation reaction is completed, purification treatment can be carried out according to a conventional method, if necessary, to obtain the target compound.

[0083] (4) Composition containing an alkene In a preferred embodiment, the composition of the present disclosure comprises: CF3-CF=CH-CF3 (1,1,1,2,4,4,4-heptafluoro-2-butene); CF3-CFH-CFH-CF3; and Contains CF3-CFH-CFH-CF2H;

[0084] The composition is preferably used as an etching gas, a refrigerant, a heat transfer medium, a deposition gas, a building block for organic synthesis, or a cleaning gas.

[0085] The production method of the present disclosure makes it possible to obtain an alkene represented by general formula (1). The compound may be obtained in the form of a composition containing an alkene represented by general formula (1) as the compound and an alkene represented by general formula (2) as the raw material compound.

[0086] The CF3-CFH-CFH-CF3 contained in the composition is, for example, an alkane compound derived from the raw material compound perfluoro-2-butene.

[0087] The CF3-CFH-CFH-CF2H contained in the composition is, for example, a 3H-alkane compound.

[0088] In the composition, the content of 1,1,1,2,4,4,4-heptafluoro-2-butene is preferably 80 mol% or more and 99.9 mol% or less, more preferably 90 mol% or more and 99.9 mol% or less, still more preferably 95 mol% or more and 99.9 mol% or less, and particularly preferably 99 mol% or more and 99.9 mol% or less, based on the total amount of the composition being 100 mol%. In the composition, the content of CF3-CF=CH-CF3 is preferably 80 mol% or more, and the contents of CF3-CFH-CFH-CF3 and CF3-CFH-CFH-CF2H are preferably 20 mol% or less, where the total amount of the composition is 100 mol%.

[0089] According to the manufacturing method of the present disclosure, 1,1,1,2,4,4,4-heptafluoro-2-butene (hydrogenated alkene) can be obtained with particularly high selectivity, and as a result, it is possible to reduce components other than 1,1,1,2,4,4,4-heptafluoro-2-butene in the composition. According to the method, the purification process to obtain 1,1,1,2,4,4,4-heptafluoro-2-butene can be carried out efficiently. can be done.

[0090] The composition is preferably used for etching to form cutting-edge fine structures in semiconductors, liquid crystals, etc. They are used as gases, refrigerants, heat transfer media, etc. Compositions containing alkenes are preferably useful in a variety of applications, such as deposit gases, building blocks for organic synthesis, cleaning gases, etc.

[0091] The deposition gas is a gas that deposits an etch-resistant polymer layer.

[0092] A building block for organic synthesis refers to a substance that can be a precursor to a compound with a highly reactive skeleton. When a composition containing 1,1,1,2,4,4,4-heptafluoro-2-butene is reacted with a fluorine-containing organosilicon compound such as CF3Si(CH3)3, a fluoroalkyl group such as a CF3 group is formed. It is possible to introduce these compounds into the catalyst and convert them into substances that can be used as cleaning agents or intermediates for fluorine-containing pharmaceuticals.

[0093] The embodiments of the present disclosure have been described above.

[0094] The embodiments of the present disclosure may take on various modifications in form and detail without departing from the spirit and scope of the appended claims. [Example]

[0095] The present disclosure will be specifically described below with reference to examples.

[0096] The present disclosure is not limited in any way by these examples.

[0097] Example Raw material compound: Perfluoro-2-butene (F3C-CF=CF-CF3) Target compound: 1,1,1,2,4,4,4-heptafluoro-2-butene (F3C-CF=CH-CF3) ((Z / E)-1327myz)) Gas chromatography: Shimadzu Corporation, product name "GC-2014" NMR: Manufactured by JEOL, product name "400YH"

[0098] The reaction tube is made of stainless steel (outer diameter: 1 / 2 inch) and is filled with palladium-supported activated carbon catalyst. After drying at 200°C for 3 hours under a nitrogen atmosphere, the temperature was raised to 400°C. After raising the temperature to 400°C, the temperature was lowered to the reaction temperature, and hydrogen diluted with nitrogen was passed through, gradually increasing the hydrogen concentration, and finally the catalyst was hydrogenated with 100% hydrogen.

[0099] A gas-phase flow reaction was carried out under atmospheric pressure, and perfluoro-2-butene (raw material compound) and perfluoro-2-butene were reacted. The contact time (W / F0) with the radium-supported activated carbon catalyst (1% Pd / C) was set to 8 g·sec / cc (%) and 17 g ·sec / cc(%), 38g·sec / cc(%), 60g·sec / cc(%), or 78g·sec / cc(%) The raw material compounds were passed through the reactor so that the

[0100] The amount of hydrogen used was H2 / alkene molar ratio: 1.1.

[0101] (H2: 1.1 moles, alkene mole: 1 mole) The reactor was heated to 200°C, 300°C, or 400°C to initiate the hydrogenation reaction of the fluorine atoms. One hour after the start of the hydrogenation reaction, the distillate that had passed through the detoxification tower was collected.

[0102] Then, mass analysis was performed by gas chromatography / mass spectrometry (GC / MS) using gas chromatography, and structural analysis was performed by NMR spectroscopy.

[0103] After the reaction was completed, mass spectrometry and structural analysis confirmed that 1,1,1,2,4,4,4-heptafluoro-2-butene was produced as the target compound.

[0104] The alkane compound CF3-CFH-CFH-CF3 derived from the raw material compound perfluoro-2-butene (F3C-FC=CF-CF3) and the 3H alkane compound CF3-CFH-CFH-CF2H were produced.

[0105] The results for each example are shown in Table 1 below.

[0106] In Table 1, the contact time (W / F) is the flow rate of the raw material gas, i.e. That is, it means the time during which the catalyst and the raw material gas are in contact with each other.

[0107] From the results of the Examples (Table 1), it can be seen that when perfluoro-2-butene, a raw material compound, is hydrogenated in the presence of a palladium-supported activated carbon catalyst, hydrogen is added, and the target compound is 1,1,1,2,4,4,4-heptafluoro-2-butene, the hydrogenation reaction can be carried out efficiently, and the hydrogenated Alkenes can be produced with high conversion, yield and / or high selectivity. The use of a palladium-on-activated carbon catalyst is a particularly preferred embodiment.

[0108] [Table 1]

Claims

[Claim 1] General formula (1): 【Chemical 1】 (In formula (1), R 1 and R 3 are the same or different and represent a trifluoromethyl group or a pentafluoroethyl group. In formula (1), R 2 represents a fluorine atom. The alkene represented by formula (1) has 5 or 6 carbon atoms. A method for producing an alkene represented by the formula: General formula (2): 【Chemistry 2】 (In formula (2), X is a fluorine atom. In formula (2), R 1 and R 3 are the same or different and represent a trifluoromethyl group or a pentafluoroethyl group. In formula (2), R 2 represents a fluorine atom. The alkene represented by formula (2) has 5 or 6 carbon atoms. An alkene represented by The method includes a step of hydrogenating the olefin in a gas phase in the presence of an activated carbon catalyst carrying a noble metal or a rare metal, The noble metal or rare metal is at least one noble metal or rare metal selected from the group consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and manganese (Mn).

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