Method for preparing nitrile rubber by using ruthenium complex catalyst
阅读说明：本技术 用钌络合物催化剂制备丁腈橡胶的方法 (Method for preparing nitrile rubber by using ruthenium complex catalyst ) 是由 维尔纳·奥布雷赫特 萨拉·戴维 希亚姆·塞勒姆 于 2018-12-05 设计创作，主要内容包括：本发明涉及一种用于在具有特殊的N-杂环卡宾配体的特定钌络合物催化剂的存在下,通过第一丁腈橡胶的复分解制备具有降低的分子量的丁腈橡胶的方法。(The invention relates to a method for producing nitrile rubbers with reduced molecular weight by metathesis of a first nitrile rubber in the presence of a specific ruthenium complex catalyst with specific N-heterocyclic carbene ligands.)
1. A process for reducing the molecular weight of nitrile rubbers, characterized in that the nitrile rubber is brought into contact and reacted with a ruthenium complex catalyst of the general formula (IA) below, optionally in the presence of a co-olefin
Wherein
X1And X2Denotes identical or different anionic ligands, preferably halogen, more preferably F, Cl, Br, I and particularly preferably Cl,
R1represents a straight or branched aliphatic C1-C20Alkyl radical, C3-C20-cycloalkyl, C5-C20Aryl, CHCH3-CO-CH3Preferably methyl, ethyl, isopropyl, isopentyl, tert-butyl, CHCH3-CO-CH3A cyclohexyl group or a phenyl group,
R2represents hydrogen, halogen, C1-C6-alkyl or C1-C6-an alkenyl group,
R3represents an electron-withdrawing group, preferably-F, -Cl, -Br, -I, -NO2、-CF3、-OCF3、-CN、-SCN、-NCO、-CNO、-COCH3、-COCF3、-CO-C2F5、-SO3、-SO2-N(CH3)2Arylsulfonyl, arylsulfinyl, arylcarbonyl, alkylcarbonyl, aryloxycarbonyl, or-NR4-CO-R5Wherein R is4And R5Are the same or different and may each independently be H, C1-C6Alkyl, perhalogenated C1-C6-alkyl, aldehyde, ketone, ester, amide, nitrile, optionally substituted aryl, pyridinium-alkyl, pyridinium-perhalogenated alkyl or optionally substituted C5-C6Cyclohexyl radical, CnH2nY or CnF2nA group Y, wherein n ═ 1 to 6 and Y represents an ionic group or a group of one of the formulae (EWG 1), (EWG 2) or (EWG 3)
Wherein
R6、R7、R8、R9、R10、R11Independently represent H, C1-C6Alkyl radical, C1-C6-perhaloalkyl or C5-C6-aryl and R9、R10、R11It is possible to form a heterocyclic ring,
X3represents an anion, halogen, tetrafluoroborate ([ BF ]4]-) [ tetrakis- (3, 5-bis (trifluoromethyl) phenyl) borate]([BARF]-) Hexafluorophosphate ([ PF ]6]-) Hexafluoroantimonate ([ SbF)6]-) Hexafluoroarsenate ([ AsF)6]-) Or trifluoromethanesulfonic acid ([ (CF)3)2N]-)；
R4And R5Together with the N and C to which they are bonded may form a compound having the formula (EWG 4) or(EWG 5) heterocycles
Wherein
hal is halogen and
R12is hydrogen, C1-C6Alkyl radical, C5-C6-cycloalkyl or C5-C6-an aryl group,
l represents an NHC ligand having the general formula (L1) or (L2)
Wherein
R13Is hydrogen, C1-C6Alkyl radical, C3-C30-cycloalkyl or C5-C30-an aryl group,
R14and R15C, which are identical or different and are straight-chain or branched3-C30Alkyl radical, C3-C30-cycloalkyl, C5-C30-aryl, C5-C30-alkylaryl, C5-C30Aralkyl with optionally up to 3 heteroatoms, preferably isopropyl, isobutyl, tert-butyl, cyclohexyl or phenyl.
2. The process for reducing the molecular weight of nitrile rubbers according to claim 1, characterized in that L corresponds to NHC ligands having the formula L1a, L2a, L1b, L2b, L1c, L2c, L1d, L2d, L1e and L2e
3. Process for reducing the molecular weight of nitrile rubbers according to claim 1 or 2, characterized in that the NHC ligand corresponds to formula L1a, L2a, L1b, L2b, L1c or L2c, more preferably L1a or L2 a.
4. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 3, characterised in that the electron-withdrawing group R3is-F, -Cl, -Br, -I, -NO2、-CF3、-OCF3、-CN、-SCN、-NCO、-CNO、-COCH3、-COCF3、-CO-C2F5、-SO3、-SO2N(CH3)2、-NHCO-H、-NH-CO-CH3、-NH-CO-CF3、-NHCO-OEt、-NHCO-OiBu、-NH-CO-COOEt、-CO-NR2、-NH-CO-C6F5or-NH (CO-CF)3)2。
5. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 4, characterised in that the electron-withdrawing group R3is-Cl, -Br, -NO2、-NH-CO-CF3-NH-CO-OiBu or-NH-CO-COOEt, more preferably-NH-CO-CF3、-NH-CO-OiBu、NH-CO-COOEt。
6. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 5, characterized in that the ruthenium complex catalyst corresponds to one of the following formulae:
7. process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 6, characterized in that the ruthenium complex catalyst is M71SIPR, M73 SIPR or M74SIPR, more preferably M73 SIPR.
8. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 7, wherein the amount of catalyst used is from 5 to 1000ppm, preferably from 5 to 500ppm, in particular from 5 to 250ppm, of noble metal, based on the nitrile rubber used.
9. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 8, in a co-olefin, preferably linear or branched C2-C16Olefins, more preferably ethylene, propylene, butene, styrene, 1-dodecene, 1-hexene and 1-octene.
10. Process for reducing the molecular weight of nitrile rubber according to any of claims 1 to 9, wherein the concentration of said nitrile rubber in said reaction mixture is in the range from 1 to 30% by weight, preferably in the range from 5 to 25% by weight, based on the whole reaction mixture.
11. Process for reducing the molecular weight of nitrile rubbers according to any of claims 1 to 10, carried out at a temperature ranging from 10 to 150 ℃, preferably ranging from 20 to 100 ℃.
12. Process for reducing the molecular weight of nitrile rubber according to any of claims 1 to 11, wherein one or more additional copolymerizable monomers are used, preferably α, β -unsaturated mono-or dicarboxylic acids or their esters or imides, more preferably fumaric acid, maleic acid, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate and methoxyethyl (meth) acrylate.
13. A process for reducing the molecular weight of nitrile rubber according to any of claims 1 to 12, wherein said metathesis reaction of nitrile rubber is followed by hydrogenation of the unsaturated C ═ C double bonds in said nitrile rubber.
14. Use of a ruthenium complex catalyst having the general formula (IA) in metathesis reactions for the metathesis of nitrile rubber, preferably in ring-closing metathesis (RCM), Cross Metathesis (CM) or ring-opening metathesis (ROMP).
Technical Field
The invention relates to a method for producing nitrile rubbers with reduced molecular weight by metathesis of a first nitrile rubber in the presence of a specific ruthenium complex catalyst having a specific N-heterocyclic carbene ligand and a specific bridged carbene ligand (having at least one electron-withdrawing group).
Background
Metathesis reactions are widely used in the context of chemical synthesis, for example in ring-closing metathesis (RCM), cross-metathesis (CM), ring-opening metathesis (ROM), ring-opening metathesis polymerization (ROMP), cyclic diene metathesis polymerization (ADMET), self-metathesis, reaction of alkenes with alkynes (ene-alkyne reaction), polymerization of alkynes, and olefinated forms of carbonyl compounds. Metathesis reactions are used, for example, in olefin synthesis, ring-opening polymerization of norbornene derivatives, depolymerization of unsaturated polymers, and synthesis of telechelics.
A number of different catalysts based on titanium, tungsten, molybdenum, ruthenium and osmium can be used to catalyze these reactions, and these have been described in the literature, for example, by: katz (Tetrahedron Lett. [ Tetrahedron bulletin ]]47,4247-]31,628-]108,2271-2273 (1986); catal [ catalysis]46,243-253 (1988); organometallics]9,2262-2275(1990)), Grubbs (WO-A-00/71554; WO-A-2007/08198; WO-A-03/011455), Herrmann (angel. chem. int.ed. [ international edition of applied chemistry ]]37,2490-2493(1998)), HoveydA (US-A-2002/0107138), Hill-F ü rstner (J.chem.Soc.Dalton Trans. [ journal of the American chemical society for Dalton album ]]1999, 285-291; chem.eur.j [ european chemistry]2001,7, 22 nd, 4811 th, 4820 th), Fogg (Organometallics)]2003,22,3634), Buchmeiser-Nuyken (macromol. symp. [ proceedings of the macromolecular symposium)]2004,217, 179-190; chem.eur.j. [ european chemistry]2004,10,777-784), Nolan (WO-A-00/15339), Dixneuf (WO 1999/28330), Mol (J.C.adv.Synth.Catal. [ advanced Synthesis and catalysis ]]2002,344, 671-Asca 677), Wagener (Macromolecules [ Macromolecules ]]2003,36,8231,8239), Piers (WO-A-2005/121158), GrelA (WO-A-2004/035596), Barbasiewicz (Organometallics [ organometallic ] compounds]2012,31,3171-; EP-A-0839821) andingelheim (org. process res. dev. [ organic process research and development ]]2005,9,513; chem. [ organic chemistry journal ]]2006,71 7133)。
The catalysts described are suitable to varying degrees for the different preceding metathesis reactions. The aforementioned catalysts are not necessarily suitable for catalyzing metathesis reactions of substrates having polar groups, especially nitrile groups, because only a few metathesis catalysts tolerate polar groups. In the metathesis of nitrile rubbers, the choice of suitable catalysts is further limited, since nitrile rubbers prepared on an industrial scale by emulsion polymerization contain not only nitrile groups but also process-specific impurities, such as initiators, redox systems, chain transfer agents, fatty acids or antioxidants, which act as catalyst poisons. Another difficulty or risk is that nitrile rubbers gel easily, causing the polymer to become insoluble and further limiting the field of use. Furthermore, the polymers can no longer be mixed sufficiently and the result is a defect in the end product.
Catalysts which are suitable in principle for the metathesis of nitrile rubbers and meet the abovementioned criteriｃA to ｃA varying extent are described, for example, in EP-A-1826220, WO-A-2008/034552, EP-A-2027920, EP-A-2028194, EP-A-2289622 and EP-A-2289623 and WO-A-2011/079799.
EP-A-1826220 describes transition metal-carbene complex catalysts of the Grubbs-HoveydｃA type II for the metathesis of nitrile rubbers, which have the following general structure (I):
wherein
M is a radical of ruthenium or osmium,
y is oxygen (O), sulfur (S), N-R1Radicals or P-R1Group, wherein R1With the definitions given below, it is possible to use,
X1and X2Represent the same or different ligands, and are,
R1represents alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulfonyl or alkylsulfinyl, all of which may each optionally be substituted by one or moreSubstituted by alkyl, halogen, alkoxy, aryl or heteroaryl,
R2、R3、R4and R5Are identical or different and represent hydrogen or an organic or inorganic radical,
R6is hydrogen or alkyl, alkenyl, alkynyl or aryl, and
l is a ligand.
In the catalyst having the general formula (I), L is a ligand, typically a ligand having an electron donor function. L may represent P (R)7)3Group, wherein R7Independently is C1-C6Alkyl radical, C3-C8-cycloalkyl or aryl, or alternatively an optionally substituted imidazolidine radical ("Im").
The imidazolidine radical (Im) typically has a structure of the formula (IIa) or (IIb)
Wherein
R8、R9、R10、R11Are identical or different and are hydrogen, straight-chain or branched C1-C30Alkyl, preferably C1-C20-alkyl radical, C3-C20Cycloalkyl, preferably C3-C10-cycloalkyl radical, C2-C20-alkenyl, preferably C2-C10-alkenyl, C2-C20Alkynyl, preferably C2-C10-alkynyl, C6-C24Aryl, preferably C6-C14-aryl radical, C1-C20-carboxylic acid esters, preferably C1-C10-carboxylic acid ester, C1-C20Alkoxy, preferably C1-C10-alkoxy radical, C2-C20Alkenyloxy, preferably C2-C10-alkenyloxy, C2-C20Alkynyloxy, preferably C2-C10-alkynyloxy, C6-C20Aryloxy radical, preferably C6-C14-aryl radicalOxy radical, C2-C20Alkoxycarbonyl, preferably C2-C10-alkoxycarbonyl, C1-C20Alkylthio, preferably C1-C10Alkylthio radical, C6-C20Arylthio, preferably C6-C14-arylthio group, C1-C20Alkylsulfonyl, preferably C1-C10-alkylsulfonyl, C1-C20Alkyl sulfonates, preferably C1-C10Alkyl sulfonates of C6-C20Aryl sulfonates, preferably C6-C14Aryl sulfonates, or C1-C20-alkylsulfinyl, preferably C1-C10-an alkylsulfinyl group.
Particularly preferred imidazolidine radicals (Im) have the following structures (IIIa to IIIf), where Mes is in each case 2,4, 6-trimethylphenyl:
the catalysts explicitly described are those having the following structure, where Mes is in each case 2,4, 6-trimethylphenyl:
the Hoveyda-type catalyst enables cross-metathesis of nitrile rubbers in the presence of 1-olefins, with Ru inputs in the range from 8.6ppm to 161ppm based on the nitrile rubber. The Hoveyda catalyst and Grela catalyst have higher activity than the Grubbs II catalyst (G II) at the same Ru loading in the range of 8.6 to 23.8ppm Ru input. The teaching of EP-A-1826220 does not disclose what structural features the catalyst must have in order to be able to further improve its efficiency in the metathesis of nitrile rubbers. More specifically, details on the design of NHC substituents and aromatic carbene ligands are lacking.
EP-A-2028194 describes catalysts having the following general structural features:
the following catalysts are explicitly mentioned:
these catalysts have a higher activity than the Grubbs II catalyst at comparable Ru contents.
A disadvantage of the catalysts described in EP-A-2028194 for the metathesis of nitrile rubbers is that the catalyst activity is too low to be commercially useful.
EP-A-2027920 describes transition metal-carbene complex catalysts having the following structural features:
the following fluorenylidene complex catalysts are explicitly mentioned:
fluorenylidene complexes have a wide range of uses and are useful in a variety of metathesis reactions including the degradation of nitrile rubber. However, they are not sufficiently active for carrying out metathesis of nitrile rubbers.
The Arlt catalyst described in WO-A-2008/034552 is used in EP-A-2289622 for the metathesis of nitrile rubbers.
In EP-A-2289622 and EP-A-2289623, the Arlt catalyst was compared with the Grubbs II catalyst in three amounts, 0.003phr, 0.007phr and 0.15 phr. In 6 experiments, the nitrile rubber degradation was carried out as cross-metathesis in the presence of 4phr of 1-hexene. Arlt catalyst gives the ratio by comparison with Grubbs II catalystLower molar masses (M) in the case of Grubbs II catalystswAnd Mn). EP-A-2289622 does not compare the activity of the Arlt catalyst with that of the Grubbs-HoveydｃA II catalyst (GH II), which is known from EP-A-1826220 to have ｃA higher activity than the Grubbs II catalyst. Furthermore, the teaching of EP-A-2289622 does not disclose how the chemical structure of the metathesis catalyst should be modified in order to give it ｃA higher activity in nitrile rubber metathesis than the Grubbs-HoveydｃA catalyst.
WO-A-2011/079799 describes A number of catalysts having monodentate N-containing and bidentate N-and O-containing ligand systems in which the ligands are bound in each case to A carbon carbene in the O-position of the aromatic system. The use of these catalysts for RCM and ROMP is described, but there is a lack of comparison with known catalysts, and so it is not possible to make a relative evaluation of the activity of the catalysts. Furthermore, metathesis and hydrogenation of double bond-containing rubbers such as nitrile rubber (NBR), styrene/butadiene rubber (SPR and SBS) and butyl rubber (IIR) are mentioned, and the metathesis and hydrogenation may be carried out sequentially or simultaneously. Examples of metathesis and simultaneous metathesis and hydrogenation of commercially available nitrile rubbers are disclosed. Metathesis was carried out using 0.04 wt%, 0.07 wt% and 0.1 wt% of catalyst 4aa, without using 1-olefin in chloroform or chlorobenzene at a temperature range from 30 ℃ to 100 ℃. Simultaneous metathesis and hydrogenation were carried out using catalyst 4ab with the same amount of catalyst.
Based on the details in WO-A-2011/079799, no predictions can be made regarding the optimization of the ligand system with regard to metathesis reactions and more particularly the metathesis of nitrile rubbers.
The catalysts for metathesis described in the aforementioned patent specifications are resistant to the impurities present in nitrile rubbers and nitrile rubbers. However, from an economic point of view, the activity of these catalysts is insufficient.
WO-A-2008/065187 describes substituted catalysts of the Grubbs-HoveydA type II (hereinafter referred to as "Mauduit catalysts") having the following structural features:
wherein
L is an uncharged ligand
X and X' represent anionic ligands
R1And R2Independently is H, C1-C6Alkyl, perhalogenated C1-C6-alkyl, aldehyde, ketone, ester, amide, nitrile, optionally substituted aryl, pyridinium-alkyl, pyridinium-perhalogenated alkyl or optionally substituted C5-C6Cyclohexyl radical, CnH2nY or CnF2nY group wherein n ═ 1 to 6 and Y represents an ionic group or a group of one of the formulae
R3Is C1-C6-alkyl or C5-C6-cycloalkyl or C5-C6-an aryl group,
R4、R5、R6、R7、R8、R9、R10、R11independently is H, C1-C6Alkyl radical, C1-C6-perhaloalkyl or C5-C6-an aryl group,
R9、R10、R11it is possible to form a heterocyclic ring,
X1is an anion, halogen, tetrafluoroborate ([ BF ]4]-) [ tetrakis- (3, 5-bis (trifluoromethyl) phenyl) borate]([BARF]-) Hexafluorophosphate ([ PF ]6]-) Hexafluoroantimonate ([ SbF)6]-) Hexafluoroarsenate ([ AsF)6]-) Triflate ([ (CF)3)2N]-)；
R1And R2With themThe bonded N and C together may form a heterocyclic ring having the formula
Wherein
hal is halogen and R12Is hydrogen, C1-C6Alkyl radical, C5-C6-cycloalkyl or C5-C6-an aryl group.
In a preferred embodiment, L is P (R)13)3Wherein R is13Is C1-C6Alkyl radical, C5-C6-aryl or C5-C6-a cycloalkyl group.
In alternative preferred embodiments, L is a ligand having formula 7a, 7b, 7c, 7d or 7 e:
wherein n is1＝0、1、2、3；
R14、R15、R16、R17、R18、R19、R20、R21、R22、R23、R24、R25、R26、R27、R28Independently is C1-C6Alkyl radical, C3-C20-cycloalkyl, C2-C20-alkenyl, naphthyl, anthracene or phenyl, wherein the phenyl may be optionally substituted with up to 5 groups selected from the group comprising: c1-C6Alkyl radical, C1-C6-an alkoxy group and a halogen,
R16and R17And R26And R27May form a ring having 3, 4,5, 6 or 7 bonds, R28Aromatic rings having 6 bonds may be independently formed.
The Mauduit catalyst selected is, for example,
the Mauduit catalyst has the feature of being easily recyclable, which enables the preparation of metathesis products with low noble metal content. In the most advantageous case, the Mauduit catalyst enables the production of products having a ruthenium content of less than 10ppm to 20 ppm.
According to WO-A-2008/065187, the catalysts described therein are suitable for A large number of metathesis reactions, but no metathesis of nitrile rubbers is mentioned. In addition, WO-A-2008/065187 lacks an index to optimize the catalyst structure, particularly the structure of the NHC ligand, to reduce the amount of catalyst in the metathesis of nitrile rubber. WO-A-2008/065187 likewise does not contain any indication as to whether the metathesis of nitrile rubbers can be enhanced by adding additives.
Furthermore, the patent literature describes ｃA number of additives with which the activity of metathesis catalysts, in particular for the metathesis of nitrile rubbers, can be enhanced (EP-A-1760093, EP-A-1894946, EP-A-2027919, EP-A-2028194, EP-A-2030988, EP-A-2143489, EP-A-2147721).
Disclosure of Invention
To enhance activity, these patent specifications specify the use of salts (e.g., lithium chloride, lithium bromide, magnesium chloride, calcium chloride, etc.) and compounds (e.g., borate esters, boron trifluoride-ether adducts, transition metal esters such as tetraalkoxytitanate esters, etc.). However, it is not possible to infer from these patent specifications what structural characteristics the ruthenium-or osmium-containing transition metal complexes must have in order to make them particularly highly active in the metathesis of nitrile rubbers.
The problem underlying the present invention was therefore to provide a process for the metathesis of nitrile rubbers, in particular of commercially available nitrile rubbers, based on catalysts which have a higher activity than those of the known catalysts, in particular of the Grubbs II, Grubbs III or Grubbs-Hoveyda type II, and which enable a very significant reduction in the molecular weight without gel formation and without an increase in PDI.
It has surprisingly been found that ruthenium complex catalysts with bridged carbene ligands with at least one Electron Withdrawing Group (EWG) meet the required requirements in an excellent way when these ruthenium complex catalysts additionally contain NHC ligands substituted with two phenyl rings, each with sterically required substituents in the o and o' positions.
The problem addressed by the present invention can therefore be solved by a process for reducing the molecular weight of nitrile rubbers in which a nitrile rubber is brought into contact with a ruthenium complex catalyst of the general formula (IA) in a metathesis reaction
Wherein
X1And X2Denotes identical or different anionic ligands, preferably halogen, more preferably F, Cl, Br, I and particularly preferably Cl,
R1represents a straight or branched aliphatic C1-C20Alkyl radical, C3-C20-cycloalkyl, C5-C20Aryl, CHCH3-CO-CH3Preferably methyl, ethyl, isopropyl, isopentyl, tert-butyl, CHCH3-CO-CH3A cyclohexyl group or a phenyl group,
R2represents hydrogen, halogen, C1-C6-alkyl or C1-C6-an alkenyl group,
R3represents an electron-withdrawing group, preferably-F, -Cl, -Br, -I, -NO2、-CF3、-OCF3、-CN、-SCN、-NCO、-CNO、-COCH3、-COCF3、-CO-C2F5、-SO3、-SO2-N(CH3)2Arylsulfonyl, arylsulfinyl, arylcarbonyl, alkylcarbonyl, aryloxycarbonyl, or-NR4-CO-R5Wherein R is4And R5Are the same or different and may each independently be H, C1-C6Alkyl, perhalogenated C1-C6-alkyl, aldehyde, ketone, ester, amide, nitrile, optionally substituted aryl, pyridinium-alkyl, pyridinium-perhalogenated alkyl or optionally substituted C5-C6Cyclohexyl radical, CnH2nY or CnF2nA group Y, wherein n ═ 1 to 6 and Y represents an ionic group or a group of one of the formulae (EWG 1), (EWG 2) or (EWG 3)
Wherein
R6、R7、R8、R9、R10、R11Independently represent H, C1-C6Alkyl radical, C1-C6-perhaloalkyl or C5-C6-aryl and R9、R10、R11It is possible to form a heterocyclic ring,
X3represents an anion, halogen, tetrafluoroborate ([ BF ]4]-) [ tetrakis- (3, 5-bis (trifluoromethyl) phenyl) borate]([BARF]-) Hexafluorophosphate ([ PF ]6]-) Hexafluoroantimonate ([ SbF)6]-) Hexafluoroarsenate ([ AsF)6]-) Or trifluoromethanesulfonic acid ([ (CF)3)2N]-)；
R4And R5Together with the N and C to which they are bonded, may form a heterocycle having the formula (EWG 4) or (EWG 5)
Wherein
hal is halogen and
R12is hydrogen, C1-C6Alkyl radical, C5-C6-cycloalkyl or C5-C6-an aryl group,
l represents an NHC ligand having the general formula (L1) or (L2)
Wherein
R13Is hydrogen, C1-C6Alkyl radical, C3-C30-cycloalkyl or C5-C30-an aryl group,
R14and R15C, which are identical or different and are straight-chain or branched3-C30Alkyl radical, C3-C30-cycloalkyl, C5-C30-aryl, C5-C30-alkylaryl, C5-C30Aralkyl with optionally up to 3 heteroatoms, preferably isopropyl, isobutyl, tert-butyl, cyclohexyl or phenyl.
In this connection it should be noted that in the context of the present invention, the definitions or parameters of the radicals listed above and below, listed in general terms or within preferred, more preferred, particularly preferred and most preferred ranges, are also included in any desired mutual combination.
Preferred NHC ligands are L1a, L2a, L1b, L2b, L1c, L2c, L1d, L2d, L1e and L2e
More preferred NHC ligands are L1a, L2a, L1b, L2b, L1c or L2 c.
Particularly preferred NHC ligands are L1a or L2 a.
R3preferably-F, -Cl, -Br, -I, -NO2、-CF3、-OCF3、-CN、-SCN、-NCO、-CNO、-COCH3、-COCF3、-CO-C2F5、-SO3、-SO2N(CH3)2、-NHCO-H、-NH-CO-CH3、-NH-CO-CF3、-NHCO-OEt、-NHCO-OiBu、-NH-CO-COOEt、-CO-NR2、-NH-CO-C6F5、-NH(CO-CF3)2。
R3More preferably-Cl, -Br, -NO2、-NH-CO-CF3、-NH-CO-OiBu、-NH-CO-COOEt。
R3Particularly preferred is-NH-CO-CF3、-NH-CO-OiBu、NH-CO-COOEt。
Preferred ruthenium complex catalysts are
More preferred ruthenium complex catalysts are M71SIPr, M73 SIPr and M74 SIPr.
A particularly preferred ruthenium complex catalyst is M73 SIPr.
The amount of ruthenium complex catalyst of the general formula (IA) or (IB) used in the molecular weight reduction according to the invention depends on the nature and catalytic activity of the particular ruthenium complex catalyst, based on the nitrile rubber used. The amount of ruthenium complex catalyst used is typically from 1ppm to 1000ppm, preferably from 2ppm to 500ppm, in particular from 5ppm to 250ppm, of noble metal, based on the nitrile rubber used.
NBR metathesis can be carried out in the absence or in addition in the presence of a co-olefin. Such co-olefins are preferably linear or branched C2-C16-an olefin. Suitable examples are ethylene, propylene, isobutene, styrene, 1-dodecene, 1-hexene or 1-octene. Preference is given to using 1-hexene or 1-octene. If the co-olefin is a liquid (like e.g. 1-hexene), the amount of co-olefin is preferably in the range of from 0.2 to 20 wt. -%, based on the nitrile rubber used. If the co-olefin is a gas, like for example ethylene, the amount of co-olefin is chosen so as to be established in the reaction vessel at room temperature in the range of from 1x 105Pa to 1x 107Pressure in the Pa range, preferably from 5.2X 105Pa to 4x 106Pressure in the Pa range.
The metathesis reaction can be carried out in a suitable solvent which does not deactivate the catalyst used nor adversely affect the reaction in any other way. Preferred solvents include, but are not limited to, dichloromethane, benzene, toluene, methyl ethyl ketone, acetone, tetrahydrofuran, tetrahydropyran, dioxane, cyclohexane, and monochlorobenzene. A particularly preferred solvent is monochlorobenzene. In some cases, the addition of further additional solvent can also be dispensed with, when the co-olefin itself can act as solvent, as is the case, for example, with 1-hexene.
The concentration of nitrile rubber used in the reaction mixture for the metathesis is not critical, but it should be noted that the reaction should not be adversely affected by too high a viscosity of the reaction mixture and associated mixing problems. Preferably, the concentration of NBR in the reaction mixture is in the range of from 1 to 30 wt. -%, more preferably in the range of from 5 to 25 wt. -%, based on the entire reaction mixture.
The metathesis degradation is typically carried out at a temperature in the range from 10 ℃ to 150 ℃, preferably at a temperature in the range from 20 ℃ to 100 ℃.
The reaction time depends on many factors, for example on the type of NBR, the type of catalyst, the catalyst concentration used and the reaction temperature. Typically, the reaction is completed within five hours under normal conditions. The progress of the metathesis can be monitored by standard analysis, for example by Gel Permeation Chromatography (GPC) measurement or by determining the viscosity.
The nitrile rubber ("NBR") used in the process according to the invention may be a co-, ter-or tetrapolymer comprising recurring units of at least one conjugated diene, at least one α, β -unsaturated nitrile and optionally one or more further copolymerizable monomers.
Any conjugated diene may be used. Preference is given to using conjugated (C)4-C6) A diene. Particularly preferred are 1, 3-butadiene, isoprene, 2, 3-dimethylbutadiene, piperylene or mixtures thereof. Particularly preferred are 1, 3-butadiene and isoprene or mixtures thereof. Very particular preference is given to 1, 3-butadiene.
The α -unsaturated nitrile used may be any of the known α -unsaturated nitriles, preferablySelecting (C)3-C5) - α -unsaturated nitriles, such as Acrylonitrile (ACN), methacrylonitrile, ethacrylonitrile or mixtures thereof acrylonitrile is particularly preferred.
Thus, a particularly preferred nitrile rubber is a copolymer of acrylonitrile and 1, 3-butadiene.
In addition to the conjugated diene and the α, β -unsaturated nitrile, one or more further copolymerizable monomers known to the person skilled in the art may be used, for example α, β -unsaturated monocarboxylic or dicarboxylic acids or esters or amides thereof.
Preferred alpha, beta-unsaturated mono-or dicarboxylic acids herein are fumaric acid, maleic acid, acrylic acid and methacrylic acid.
The esters of alpha, beta-unsaturated carboxylic acids used are
Alkyl (meth) acrylates, especially C (meth) acrylate1-C18Alkyl esters, preferably n-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate or n-hexyl (meth) acrylate;
alkoxyalkyl (meth) acrylates, especially C (meth) acrylate1-C18Alkoxyalkyl esters, preferably (meth) acrylic acid C4-C12-an alkoxyalkyl ester;
hydroxyalkyl (meth) acrylates, especially C (meth) acrylate1-C18Hydroxyalkyl esters, preferably (meth) acrylic acid C4-C12-a hydroxyalkyl ester;
cycloalkyl (meth) acrylates, especially C (meth) acrylate5-C18Cycloalkyl esters, preferably C (meth) acrylic acid6-C12-cycloalkyl esters, more preferably cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate;
alkylcycloalkyl (meth) acrylates, especially C (meth) acrylate6-C12Alkylcycloalkyl esters, preferably C (meth) acrylic acid7-C10Alkylcycloalkyl esters, more preferably methylcyclopentyl (meth) acrylate and ethylcyclohexyl (meth) acrylate；
Aryl monoesters, in particular C6-C14Aryl monoesters, preferably phenyl (meth) acrylate or benzyl (meth) acrylate;
esters of alpha, beta-ethylenically unsaturated carboxylic acids containing amino groups, such as dimethylaminomethyl acrylate or diethylaminoethyl acrylate;
alpha, beta-ethylenically unsaturated monoalkyldicarboxylic acid esters, preferably
Omicron alkyl monoesters, especially C4-C18Alkyl monoesters, preferably n-butyl, tert-butyl, n-pentyl or n-hexyl monoesters, more preferably mono-n-butyl maleate, mono-n-butyl fumarate, mono-n-butyl citraconate, mono-n-butyl itaconate, most preferably mono-n-butyl maleate,
omicron alkoxyalkyl monoesters, especially C4-C18Alkoxyalkyl monoesters, preferably C4-C12-an alkoxyalkyl monoester,
omicron hydroxyalkyl monoesters, in particular C4-C18Hydroxyalkyl monoesters, preferably C4-C12-a hydroxyalkyl monoester,
omicron cyclic alkyl monoesters, especially C5-C18Cycloalkyl monoesters, preferably C6-C12Cycloalkyl monoesters, more preferably monocyclopentyl maleate, monocyclopentyl fumarate, monocyclopentyl citraconate, monocyclohexyl citraconate, monocyclopentyl itaconate, monocyclohexyl itaconate and monocyclopentyl itaconate,
omicron alkylcycloalkyl monoesters, in particular C6-C12Alkylcycloalkyl monoesters, preferably C7-C10Alkylcycloakyl monoesters, more preferably monomethylcyclopentyl and monoethylcyclohexyl maleate, monomethylcyclopentyl and monoethylcyclohexyl fumarate, monomethylcyclopentyl citraconate and monoethylcyclohexyl citraconate; monomethyl cyclopentyl itaconate and monoethyl cyclohexyl itaconate;
omicron aryl monoesters, especially C6-C14Aryl monoesters, preferably monoaryl maleate, monoaryl fumarate, monoaryl citraconate or monoaryl itaconate, more preferably monophenyl or monobenzyl maleate, monophenyl or monobenzyl fumarate, monophenyl or monobenzyl citraconate, monophenyl or monobenzyl itaconate,
omicron unsaturated polyalkyl polycarboxylates, such as dimethyl maleate, dimethyl fumarate, dimethyl itaconate, or diethyl itaconate.
Mixtures of the foregoing esters may also be used.
The esters of α, β -unsaturated carboxylic acids used are preferably alkyl and alkoxyalkyl esters thereof. Particularly preferred alkyl esters of α, β -unsaturated carboxylic acids are methyl acrylate, ethyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and octyl acrylate. Particularly preferred alkoxyalkyl esters of α, β -unsaturated carboxylic acids are methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate. The preferred alpha, beta-ethylenically unsaturated carboxylic acid esters used are also those derived from PEG acrylates of the general formula (I)
Wherein
R is unbranched or branched C1-C20Alkyl, preferably C2-C20-an alkyl group, more preferably an ethyl, butyl or ethylhexyl group,
n is 2 to 12, preferably 2 to 8, more preferably 2 to 5 and most preferably 2 or 3, and
R1is hydrogen or CH3-。
The term "(meth) acrylate" in the context of the present invention means "acrylate" and "methacrylate". When R in the formula (I)1The radical being CH3-when the molecule is a methacrylate.
In the context of the present invention, the term "polyethylene glycol" or the abbreviation "PEG" denotes an ethylene glycol segment having two repeating ethylene glycol units (PEG-2; n ═ 2) to 12 repeating ethylene glycol units (PEG-2 to PEG-12; n ═ 2 to 12).
The term "PEG acrylate" is also abbreviated PEG-X- (M) a, where "X" is the number of repeating ethylene glycol units, "MA" is methacrylate and "a" is acrylate.
Acrylate units derived from PEG acrylates having the general formula (I) are referred to as "PEG acrylate units" in the context of the present invention.
Preferred PEG acrylate units are derived from PEG acrylates having the following formulae No. 1 to No. 8, wherein n is 2,3, 4,5, 6, 7, 8, 9, 10, 11 or 12, preferably 2,3, 4,5, 6, 7 or 8, more preferably 2,3, 4 or 5 and most preferably 2 or 3:
other common names for ethoxylated polyethylene glycol acrylates (formula No. 1) are for example poly (ethylene glycol) ethyl ether acrylate, ethoxylated PEG acrylate, ethoxylated poly (ethylene glycol) monoacrylate or poly (ethylene glycol) monoethylether monoacrylate.
These PEG acrylates may be obtained, for example, from Arkema and lacoma
In a preferred embodiment, the amount of PEG acrylate units in the nitrile rubber is in the range of from 0 to 65 wt. -%, preferably from 20 to 60 wt. -%, and more preferably from 20 to 55 wt. -%, based on 100 wt. -% total of all monomer units.
In an alternative embodiment, the amount of PEG acrylate units in the nitrile rubber is from 20 to 60 wt% and the amount of further α, β -ethylenically unsaturated carboxylic ester units other than PEG acrylate units is from 0 to 40 wt%, based on 100 wt% total of all monomer units, wherein the total amount of carboxylic ester units does not exceed 60 wt%.
In an alternative embodiment, the nitrile rubber contains not only α, β -ethylenically unsaturated nitrile units, conjugated diene units and PEG acrylate units derived from PEG acrylates having the general formula (I), but also monoalkyl dicarboxylate units, preferably monobutyl maleate, as unsaturated carboxylate ester units.
In preferred nitrile rubbers, the α, β -ethylenically unsaturated nitrile units are derived from acrylonitrile or methacrylonitrile, more preferably from acrylonitrile, the conjugated diene units are derived from isoprene or 1, 3-butadiene, more preferably from 1, 3-butadiene, and the α, β -ethylenically unsaturated carboxylate units are only PEG acrylate units derived from PEG acrylates having the general formula (I) (wherein n is 2 to 8), more preferably from PEG acrylates having the general formula (I) (wherein n is 2 or 3), wherein no further carboxylate units are present.
In another preferred nitrile rubber, the α, β -ethylenically unsaturated nitrile units are derived from acrylonitrile or methacrylonitrile, more preferably from acrylonitrile, the conjugated diene units are derived from isoprene or 1, 3-butadiene, more preferably from 1, 3-butadiene, and the α, β -ethylenically unsaturated carboxylate units are derived from a first PEG acrylate having the general formula (I) (wherein n is 2 to 12), more preferably from a PEG acrylate having the general formula (I) (wherein n is 2 or 3), and the α, β -ethylenically unsaturated carboxylate units are different from the PEG acrylate units.
Furthermore, the nitrile rubber may contain one or more further copolymerizable monomers in an amount of from 0 to 20% by weight, preferably from 0.1 to 10% by weight, based on 100% by weight total of all monomer units. In this case, the amount of further monomer units is reduced in a suitable manner such that the sum of all monomer units is always 100% by weight. The nitrile rubbers may contain one or more further copolymerizable monomers
Aromatic vinyl monomers, preferably styrene, alpha-methylstyrene and vinylpyridine,
fluorine-containing vinyl monomers, preferably fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-fluoromethylstyrene, vinyl pentafluorobenzoate, vinylidene fluoride and tetrafluoroethylene, or else
α -olefins, preferably C2-C12Olefins, such as ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene or 1-octene,
non-conjugated dienes, preferably C4-C12Dienes such as 1, 4-pentadiene, 1, 4-hexadiene, 4-cyanocyclohexene, 4-vinylcyclohexene, vinylnorbornene, dicyclopentadiene, or else
Alkynes such as 1-or 2-butyne,
alpha, beta-ethylenically unsaturated monocarboxylic acids, preferably acrylic acid, methacrylic acid, crotonic acid or cinnamic acid,
alpha, beta-ethylenically unsaturated dicarboxylic acids, preferably maleic acid, fumaric acid, citraconic acid, itaconic acid,
copolymerizable antioxidants, for example N- (4-anilinophenyl) acrylamide, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) cinnamamide, N- (4-anilinophenyl) crotonamide, N-phenyl-4- (3-vinylbenzyloxy) aniline, N-phenyl-4- (4-vinylbenzyloxy) aniline, or
Crosslinkable monomers, for example divinyl components, such as divinylbenzene for example.
In an alternative embodiment, the nitrile rubber contains, as PEG acrylate units, ethoxy, butoxy or ethylhexyloxy polyethylene glycol (meth) acrylates comprising 2 to 12 repeating ethylene glycol units, more preferably ethoxy or butoxy polyethylene glycol (meth) acrylates comprising 2 to 5 repeating ethylene glycol units and most preferably ethoxy or butoxy polyethylene glycol (meth) acrylates comprising 2 or 3 repeating ethylene glycol units.
In another alternative embodiment of the nitrile rubber, n is 2 or 3, R is ethyl or butyl and R is1Is hydrogen or methyl, preferably n is 2, R is butyl and R is1Is methyl.
In another alternative embodiment, the nitrile rubber comprises 8 to 18 wt% acrylonitrile units, 27 to 65 wt% 1, 3-butadiene units, and 27 to 55 wt% PEG-2 acrylate units or PEG-3 acrylate units.
In another alternative embodiment, the nitrile rubber comprises
13 to 17% by weight of alpha, beta-ethylenically unsaturated nitrile units, preferably acrylonitrile,
36 to 44% by weight of conjugated diene units, preferably 1, 3-butadiene, and
43 to 47% by weight of PEG acrylate units derived from PEG acrylate (preferably butoxydiethylene glycol methacrylate) having the general formula (I).
The ratio of conjugated diene to α, β -unsaturated nitrile to be used in the NBR polymer can vary within wide limits. The proportion or total amount of conjugated dienes is typically in the range from 40 to 90% by weight, preferably in the range from 55 to 85% by weight, based on the total polymer. The proportion or total amount of α, β -unsaturated nitriles is typically in the range from 10 to 60% by weight, preferably in the range from 15 to 45% by weight, based on the total polymer. The proportions of these monomers add up to 100% by weight in each case. The additional monomer may be present in an amount of from 0 wt% to 40 wt%, preferably from 0.1 wt% to 65 wt%, more preferably from 1 wt% to 30 wt%, based on the total polymer. In this case, the respective proportions of the conjugated diene or dienes and/or the alpha, beta-unsaturated nitrile or nitriles are replaced by the proportions of the further monomers, wherein the proportions of all monomers in each case add up to 100% by weight.
The preparation of nitrile rubbers by polymerization of the aforementioned monomers is sufficiently well known to the person skilled in the art and is widely described in the literature (e.g. w. hofmann, Rubber chem. technol. [ Rubber chemistry techniques ]36 (1963)).
Nitrile rubbers which can be used in the manner of the invention are also commercially available, for example as those from ARLANXEO Deutschland GmbHAnd
The nitrile rubbers used for the metathesis have a Mooney viscosity (ML 1+4 at 100 ℃) in the range from 30 to 100, preferably from 30 to 50. This corresponds to a weight average molecular weight Mw in the range from 150000 to 500000g/mol, preferably in the range from 180000 to 400000 g/mol. The nitrile rubbers used also have a polydispersity PDI ═ Mw/Mn in the range from 2.0 to 8.0 and preferably in the range from 2.0 to 6.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight.
The Mooney viscosity is determined here according to ASTM standard D1646.
The nitrile rubbers obtained by the metathesis process according to the invention have a Mooney viscosity (ML 1+4 at 100 ℃) in the range from 5 to 35, preferably in the range from 5 to 25. This corresponds to a weight average molecular weight Mw in the range from 10000 g/mol to 150000 g/mol, preferably in the range from 10000 g/mol to 100000 g/mol. The nitrile rubbers obtained also have a polydispersity PDI ═ Mw/Mn, where Mn is the number average molecular weight, in the range from 1.4 to 4.0, preferably in the range from 1.5 to 3.0.
The invention also provides the use of the ruthenium complex catalyst in metathesis reactions for the metathesis of nitrile rubbers. The metathesis reaction may be, for example, ring-closing metathesis (RCM), cross-metathesis (CM) or additionally ring-opening metathesis (ROMP). Typically, for this purpose, nitrile rubber is contacted and reacted with a ruthenium complex catalyst.
The use according to the invention is a process for reducing the molecular weight of nitrile rubber by contacting nitrile rubber with a ruthenium complex catalyst. This reaction is a cross metathesis.
The metathesis degradation in the presence of the catalyst system according to the invention can be followed by hydrogenation of the resulting degraded nitrile rubber. This can be done in a manner known to those skilled in the art.
The hydrogenation may be carried out using a homogeneous or heterogeneous hydrogenation catalyst. It is also possible to carry out the hydrogenation in situ, i.e. in the same reaction mixture in which the metathetic degradation has also previously been carried out and there is no need to isolate the degraded nitrile rubber. The hydrogenation catalyst is simply added to the reaction vessel.
The catalysts used are typically based on rhodium, ruthenium or titanium, but it is also possible to use platinum, iridium, palladium, rhenium, ruthenium, osmium, cobalt or copper as metal or else preferably in the form of metal compounds (see, for example, A-3,700,637, DE-A-2539132, EP-A-0134023, DE-A-3541689, DE-A-3540918, EP-A-0298386, DE-A-3529252, DE-A-3433392, US-A-4,464,515 and US-A-4,503,196).
Suitable catalysts and solvents for the hydrogenation in the homogeneous phase are described below and are also known from DE-A-2539132 and EP-A-0471250.
The selective hydrogenation can be effected, for example, in the presence of rhodium or ruthenium catalysts. Catalysts of the general formula
(R1 mB)lM Xn
Wherein M is ruthenium or rhodium, R1Are the same or different and are C1-C8Alkyl radical, C4-C8Cycloalkyl radical, C6-C15Aryl or C7-C15Aralkyl, B is a phosphorus, arsenic, sulfur or sulfoxide group S ═ O, X is hydrogen or an anion, preferably halogen, and more preferably chlorine or bromine, l is 2,3 or 4, m is 2 or 3, and n is 1, 2 or 3, preferably 1 or 3. Preferred catalysts are tris (triphenylphosphine) rhodium (I) chloride, tris (triphenylphosphine) rhodium (III) chloride, tris (dimethyl sulphoxide) rhodium (III) chloride and also those of the formula ((C)6H5)3P)4Tetrakis (triphenylphosphine) rhodium hydride of RhH and corresponding compounds, wherein triphenylphosphineHas been completely or partially substituted by tricyclohexylphosphine. The catalyst may be used in small amounts. Suitable amounts are in the range from 0.01 to 1 wt%, preferably in the range from 0.03 to 0.5 wt% and more preferably in the range from 0.05 to 0.3 wt% based on the weight of the polymer.
It is typically desirable to use a catalyst in conjunction with a cocatalyst which is of the formula R1Ligands of mB, wherein R1M and B are each as defined above for the catalyst. Preferably, m is 3, B is phosphorus, and R is1The groups may be the same or different. The cocatalyst preferably has a trialkyl, tricycloalkyl, triaryl, triaralkyl, diarylmonoalkyl, diarylmonocycloalkyl, dialkylmonoaryl, dialkylmonocycloalkyl, dicycloalkylmonoaryl or dicycloalkylmonoaryl group.
Examples of cocatalysts can be found, for example, in US-A-4631315. The preferred cocatalyst is triphenylphosphine. Further, preferably, the weight ratio of the rhodium catalyst to the co-catalyst is in the range of from 1:1 to 1:55, more preferably in the range of from 1:3 to 1: 30. Based on 100 parts by weight of the nitrile rubber to be hydrogenated, from 0.1 to 33 parts by weight of a cocatalyst, preferably from 0.2 to 20 parts by weight and even more preferably from 0.5 to 5 parts by weight, in particular more than 0.9 parts by weight but less than 5 parts by weight, based on 100 parts by weight of the nitrile rubber to be hydrogenated, are used in a suitable manner.
The actual implementation of this hydrogenation is sufficiently well known to the person skilled in the art from US-A-6683136. It is typically carried out by contacting the nitrile rubber to be hydrogenated with hydrogen in a solvent such as toluene or monochlorobenzene at a temperature in the range from 100 ℃ to 150 ℃ and a pressure in the range from 5MPa to 15MPa for 2 hours to 10 hours.
Hydrogenation is understood in the context of the present invention to mean conversion of the double bonds present in the starting nitrile rubber to an extent of at least 50%, preferably from 70% to 100%, more preferably from 80% to 100%. It is also particularly preferred that the residual content of double bonds in HNBR is from 0% to 8%.
When heterogeneous catalysts are used, these catalysts are typically supported catalysts based on palladium, for example, they are supported on carbon, silica, calcium carbonate or barium sulfate.
On completion of the hydrogenation, a hydrogenated nitrile rubber having a Mooney viscosity (ML 1+4 at 100 ℃) in the range from 1 to 50 measured according to ASTM standard D1646 is obtained. This corresponds approximately to a weight-average molecular weight Mw in the range from 2000 to 400000 g/mol. Preferably, the mooney viscosity (ML 1+4, at 100 ℃) is in the range from 5 to 40. This corresponds approximately to a weight average molecular weight Mw in the range from about 20000 to 200000 g/mol. The hydrogenated nitrile rubbers obtained also have a polydispersity PDI in the range from 1 to 5 and preferably in the range from 1.5 to 3, Mw/Mn, where Mw is the weight average molecular weight and Mn is the number average molecular weight.
Detailed Description
Examples of the invention
Description of the analytical methods
Gel Permeation Chromatography (GPC) procedure:
molecular weight MnAnd MwCalculated by Waters Empower 2 database software and determined using the following equipment: shimadzu LC-20AT High Performance Liquid Chromatography (HPLC) pump, SFD S5200 autosampler, 3 PLgel 10. mu. mMixed-B columns (300X 7.5mm ID), Shodex RI-71 detector, ERC column incubator. GPC experiments were carried out at 40 ℃ and a flow rate of 1ml/min, with Tetrahydrofuran (THF) as eluent. The GPC column was calibrated with standard Polystyrene (PS) samples.
Determination of residual double bond ("RDB") content:
RDB (in%) was determined by the following FT-IR method: spectra of the nitrile rubbers were recorded before, during and after the hydrogenation reaction by a Thermo Nicolet FT-IR spectrometer, model AVATAR 360. The NBR solution in monochlorobenzene was applied to NaCl discs and dried in order to obtain membranes for analysis. The hydrogenation rate was determined by FT-IR analysis according to ASTM standard D5670-95.
Determination of Mooney viscosity:
the determination of the Mooney viscosity is determined by the method of ASTM standard D1646. The Mooney viscosity ML [email protected] ℃ is measured at 100 ℃ with a preheating time of one minute and a measuring time of 4 minutes.
Determination of brookfield viscosity:
the solution viscosity of the polymer solution in MCB was determined using a Brookfield LV DV II + rotational viscometer. Measurements were made using a 62 standard rotor at a temperature of 23 ℃. + -. 0.1 ℃ in a 400ml beaker containing 250ml of polymer solution.
II materials for
Table 1 summarizes the results used in the examples described belowNot according to the inventionCatalysts (Grubbs II, Grubbs-Hoveyda II, Zhan 1B, M71SIMes and M73 SIMes).
Table 2 summarizes the catalysts of the invention (M71 SIPr, M73 SIPr, M74SIPr) used in the examples described below.
Table 1:using catalysts not according to the invention
Table 2:use of the catalyst of the invention
Description of the drawings:
ph in each case denotes a phenyl radical.
Dpp in each case denotes diisopropylphenyl.
Mes in each case denotes 2,4, 6-trimethylphenyl.
Nitrile rubber used
The examples described below were carried out using different grades of NBR and HNBR from Arlandidae, Germany, Inc. These nitrile rubbers have the characteristic indices shown in Table 2.
Table 2:nitrile rubber used
PDI＝Mw/Mn(ii) a MU-mooney unit
Table 3:additive for use
III metathesis reaction:
table 3 gives an overview of inventive examples, identified with an "@", and corresponding non-inventive reference examples.
In examples 1a to 8b and 12 to 17, the nitrile rubber degradation was carried out in the form of a cross-metathesis, to which 1-hexene was added. In the inventive examples and the corresponding reference examples, the catalyst was used in such an amount that the ruthenium input was 9ppm and 18ppm in each case.
In examples 9, 10 and 11, the degradation of nitrile rubber was carried out in the form of self-metathesis without addition of 1-hexene. These examples were carried out at a ruthenium input of 67 ppm.
In examples 17 and 18, metathesis of partially hydrogenated nitrile rubbers was carried out. The metathesis was carried out without addition of 1-olefin (self-metathesis) at a ruthenium input of 151ppm and at 100 ℃.
Table 3:summary of the experiments performed (═ experiments of the invention)
G II ═ Grubbs II catalyst; GH II ═ Grubbs-Hoveyda II catalyst;
sequence of metathesis reactions
All metathesis reactions were carried out in solution using monochlorobenzene (from aldrich) (hereinafter "MCB"). Prior to use, MCB was distilled and inerted at room temperature by passing nitrogen therethrough. The amounts of nitrile rubber indicated in the table below were dissolved in MCB at room temperature under stirring over a period of 12 hours. The additive (olefin) indicated in the table was added to the rubber-containing solution and stirred for 2 hours for homogenization. For experiments with the additive, the additive was added at this point and the rubber-containing solution was stirred for an additional 1 hour. The rubber solution in monochlorobenzene was heated to the temperature indicated in the table before the catalyst was added. Reaction mixtures 1 to 11 were designed so that the rubber concentration after catalyst addition was 15 wt.%; reaction mixtures 12 and 13 were designed so that the rubber concentration after catalyst addition was 10 wt.%.
The metathesis catalysts (see Table 1) were dissolved in 1ml (0.0066mmol of catalyst) or 2ml (0.013mM of catalyst) of MCB each and added immediately to the nitrile rubber solution. The metathesis reaction was started by adding a catalyst and monitored at regular time intervals (1 hour, 3 hours, 24 hours) by measuring the average molecular weight via gel permeation chromatography. Samples taken for molecular weight determination (5 ml each) were stopped immediately by adding 0.8ml of ethyl vinyl ether. The viscosity of the final sample (after a reaction time of 24 hours) was also determined in solution by means of a Brookfield viscometer (measurement temperature: 21 ℃).
Inventive and comparative examples
Examples 1a and b:reaction of NBR with Grubbs II catalyst
Examples 2a and b:reaction of NBR with Grubbs-Hoveyda II catalyst
Examples 3a and b:reaction of NBR with Zhan 1B catalyst
Examples 4a and b:reaction of NBR with M71SIMes catalyst
Examples 5a and b: reaction of NBR with M71SIPr catalyst
Examples 6a and b:reaction of NBR with M73SIMes catalyst
Examples 7a and b: reaction of NBR with M73 SIPr catalyst
Examples 8a and b:reaction of NBR with M74SIPr catalyst
Example 9:reaction of NBR with M73SIMes catalyst (in the absence of olefin)
Example 10 a:reaction of NBR with M73 SIPr catalyst (in the absence of olefins)
Example 11:reaction of NBR with Grubbs-Hoveyda II catalyst (in the absence of olefin)
Example 12-16:reaction of NBR with M71SIPr or M73 SIPr catalyst and addenda in the Presence of olefins
Experiment 17: reaction of HNBR with M73 SIPr catalyst (in the absence of olefins)
Example 18: reaction of HNBR with Grubbs-Hoveyda II catalyst (in the absence of olefin)
After a reaction time of 24 hours, inventive examples 5a, 5b, 7a, 7b, 8a and 8b show lower molar masses (M73 SIPr and M74SIPr) in the cross metathesis of nitrile rubbers with 1-hexene than in inventive examples 1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b, 6a and 6b in which Grubbs-II, Grubbs-Hoveyda, Zhan 1B, M71SIMES and M73SIMES catalysts are used (M71 SIPr, M73 SIPr and M74SIPr)wAnd Mn). Lower molar masses were achieved with catalyst input of both 9ppm Ru and 18ppm Ru.
Furthermore, it is shown that in order to achieve an equal final molar mass of the nitrile rubber, in the case of the present invention using the catalysts M71SIPR, M73 SIPR and M74SIPR, the amount of ruthenium can be reduced compared to the case of the catalysts Grubbs-II, Grubbs-Hoveyda, Zhan 1B, M71SIMes and M73 SIMes. The reduction in the amount of expensive noble metals makes it more economically feasible to carry out the cross-metathesis of nitrile rubbers.
Examples 9, 10 and 11 show that, with the same ruthenium input of 67ppm, the molar mass of the nitrile rubber (M) after a reaction time of 24 hours, using M73 SIPR (example 10) according to the invention for the self-metathesis of nitrile rubbers (without addition of 1-olefin as co-olefin), in comparison with the case of M73SIMes (example 9) and Grubbs-Hoveyda II (example 11), is greater than in the case of the same ruthenium input of 67ppmwAnd Mn) And lower. Example 10 shows that the use of the catalyst M73 SIPr according to the invention enables a more economical use of ruthenium than the catalysts used hitherto for the metathesis of nitrile rubbers.
Example 17 shows that the use of the catalyst M73 SIPR according to the invention gives a lower molar mass after 24 hours in the self-metathesis of partially hydrogenated nitrile rubbers compared with the Grubbs-Hoveyda II catalyst (example 18) (M73 SIPR)wAnd Mn). The use of the catalyst M73 SIPR in the present invention enables more economical use of expensive noble metal ruthenium.
IV hydrogenation
The following hydrogenations were carried out using NBR-8 from Arlansinaceae Germany, Inc., which has the characteristics listed in Table 2.
Hydrogenation procedure
Dried Monochlorobenzene (MCB) was purchased from VWR company and used as obtained. The results of the hydrogenation experiments are summarized in table 4.
The hydrogenation 1 to 4 was carried out in a 10l high-pressure reactor under the following conditions:
solvent: monochlorobenzene
Substrate: NBR-8
Solid concentration: 12 wt.% NBR-8 in MCB (518g)
The reactor temperature: 137 to 140 DEG C
Reaction time: 4h
The loading of the catalyst is as follows: 0.2027g (0.04phr)
Hydrogen pressure (p H)2)：8.4MPa
Stirring speed: 600rpm
The polymer solution containing NBR-8 is stirred vigorously with H2Degassing (23 deg.C, 2.0MPa) for 3 times. The temperature of the reactor was raised to 100 ℃ and H was added2The pressure rose to 60 bar. A solution of 50g of catalyst (0.2027g) in monochlorobenzene was added and the pressure was raised to 8.4MPa while the reactor temperature was adjusted to 138 ℃. Both parameters were kept constant during the reaction. The progress of the reaction was monitored by measuring the residual double bond content (RDB) of the nitrile rubber by IR spectroscopy. The reaction was terminated after 4 hours by releasing the hydrogen pressure.
Table 4:brief description of the hydrogenation experiments
The examples listed above show that the hydrogenation of the catalysts M73 SIPr and M71SIPr of the invention proceeds at least equally well or even significantly faster than the catalysts M73SIMes and M71SIMes under equivalent experimental conditions.
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